: Engine parts cleaning during overhaul



maeng9981
09-27-12, 06:35 AM
I'm currently on my mission to rebuild a 99 Northstar that was in my Deville. I originally planned to repair what's necessary, but after I got the engine out, I changed my mind. I'm pretty much going to disassemble this engine, replace as much as I can as needed, and put it all back together.

http://i.imgur.com/mgPz3.jpg http://i.imgur.com/4BoSo.jpg

(I know, that cv axle went south.)

The engine has the infamous halfcase leak and the bottom half is basically all oil residue. It pretty much looks like an iron block due to the stuff. As the engine gets disassembled, I want to clean all the residue and make it look like a new engine in the cover of a magazine. The question is: how would one approach this, with the parts all disassembled? (For instance, block exterior and interior, pistons, various accessory components and also the heads) The cleaning method must not mess with the internals and should be safe for all components. What good techniques have y'all used to clean it while rebuilding?

automark
09-27-12, 02:26 PM
Hi, It's really hard to clean the aluminum really well, but still maintain the factory finish. Often, in the Little British Car world, people will glass bead the exterior of cases. But that is really not likely in this case due to size, disassembly needs, and your location. Perhaps, once the grease, dirt and oil are thoroughly cleaned you could try certain softer "wire brush attachments" mounted in a variable speed drill.
I've seen it make the LBC tranny cases look really good. I think the wire brush used was new, copper bristles. ( The reason they used copper was that they'd heard that steel or coated steel wires could leave some of "themselves" behind, and thus rust when exposed to the elements later.) One other case I'd seen was ultimately coated with a hi heat clear coat after all of that cleaning. It looked really great and shiny, and beautiful. But, it certainly didn't look stock.
You must have, of course, by now, heard about keeping the scotch brand ( ?3M?) products away from engines for fear of that product imbedding itself in metals in the internals of engines. So thus, I head towards metal brushes.

Actual grease removers; that remains personal preference and tolerance for vapors or smells.

I wish you the best of luck and would like to hear / see what works best for you.

Best, MSH

rodnok01
09-27-12, 02:35 PM
If you want it really clean have it hot tanked at a machine shop. Has to be completely apart. Costs a few bucks but it'll look good, as for keeping that way good luck. Paint the VC's.
I've painted a few trans and engines and if perfectly clean it'll stick and last, the clear is gonna yellow some no matter what you do.

Submariner409
09-27-12, 04:00 PM
Completely disassemble the engine down to block, pan, halfcase and heads. Have all 5 hot-tanked, then come home and scrub it all with HOT water, soap, and a set of long engine cleaning bristle brushes - oil passages and all. Rinse thoroughly with HOT water, blow dry (80# air compressor), and coat the cylinder bores with 30W oil while you begin the rebuild. Use assembly lube on all new bearings and valvetrain parts.

If you really get anal you can mask off the block, halfcase and pan and prime/paint it your favorite engine color - there are primers and enamels specially for engines. Clean out the exhaust crossunder Y-pipe (excess pipe flash) and have it and the manifolds done in a chrome JetHot finish.

vincentm
09-27-12, 05:40 PM
Remember the VC's dont get painted, they get powdercoated, and um...go with red :P

Submariner409
09-27-12, 05:58 PM
Gold metalflake Candy Apple Red.

vincentm
09-27-12, 06:01 PM
Completely disassemble the engine down to block, pan, halfcase and heads. Have all 5 hot-tanked, then come home and scrub it all with HOT water, soap, and a set of long engine cleaning bristle brushes - oil passages and all. Rinse thoroughly with HOT water, blow dry (80# air compressor), and coat the cylinder bores with 30W oil while you begin the rebuild. Use assembly lube on all new bearings and valvetrain parts.

If you really get anal you can mask off the block, halfcase and pan and prime/paint it your favorite engine color - there are primers and enamels specially for engines. Clean out the exhaust crossunder Y-pipe (excess pipe flash) and have it and the manifolds done in a chrome JetHot finish.


Then sell that Deville to me, actually i might be getting a mint condition 99 Deville for $600 in the next month or so that has bad HG's.

CadillacLuke24
09-27-12, 09:24 PM
And you're gonna take it to CCC to have it studded....

:thumbsup:

Ranger
09-27-12, 10:15 PM
Maeng, you're a glutton for punishment.

maeng9981
09-28-12, 06:41 AM
Yes, I am aware of the "no-no" on scotch brite products. I guess I'll try the various de-greasers first. Wire brushing the block outer surface? Would that be safe? (Never tried) If not satisfactory, then I can try "hot tank" method. I like the way Sub suggested.

Anyway, the engine is off the transmission and is ready for teardown.

http://i.imgur.com/g0PoD.jpg

http://i.imgur.com/GyDIT.jpg

http://i.imgur.com/lqZH9.jpg

http://i.imgur.com/xj8Qp.jpg

http://i.imgur.com/XpT3M.jpg

http://i.imgur.com/AUwCU.jpg

You definitely see which cylinder was leaking
http://i.imgur.com/VNkAH.jpg

The gasket actually looked much better than what was in the Seville, except that one spot-
http://i.imgur.com/2vypD.jpg

Head bolts all came out clean
http://i.imgur.com/QJyVY.jpg

Honing pattern (110,000 miles)
http://i.imgur.com/xMg9q.jpg

Here's the head bolt length difference between 93-99 and 00-03 engines. (Shorter 93-99, longer 00-03)
http://i.imgur.com/dRiNk.jpg

One mistake I made during the installation of the engine on the stand - I forgot to take the flywheel and the oil seal off. And that made me thinking - I have no tool to remove the crankshaft rear oil seal. Getting the engine off the stand is no problem - but any suggestions how to get the rear oil seal off? Do I have to have the two removal/installation tool? Those are like $150 for one time use.

vincentm
09-28-12, 08:20 PM
And you're gonna take it to CCC to have it studded....

:thumbsup:


Hell yea, Tim would love to get his hands on it.

mtflight
09-28-12, 08:58 PM
Maeng9981 has studded his daily driver Seville and he plans to stud this one too. All in house!

As far as cleaning, I would think any food or laundry detergent will degrease very well, and standard engine degreasers probably use the same technology. CHR Fab has some fancy parts, but $$$ http://www.chrfab.com/cam_covers.htm



http://i.imgur.com/2vypD.jpg




Well no bolt hole failure on this one, at least not this bank. The missing chunk on this gasket is in the uncompressed area hanging down into the open deck coolant passage/water jacket. Sub didn't you imply that if the fire rings are not blown out/open, then coolant went around them from loss of clamping pressure - and that those fire rings clamp around the entire circumference of the cylinder on both sides of the gasket - you mentioned coolant did NOT run "through" the gasket material into a cylinder.

No evidence of nasty thread damage and porosity in these bolt holes either..... let's wait for the other bank.

If this had been an MLS gasket, with no possible hole in the water jacket... would it have failed? Rhetorical question.

Submariner409
09-28-12, 09:39 PM
Sub didn't you imply that if the fire rings are not blown out/open, then coolant went around them from loss of clamping pressure - and that those fire rings clamp around the entire circumference of the cylinder on both sides of the gasket - you mentioned coolant did NOT run "through" the gasket material into a cylinder.

I didn't "imply" anything - I stated a fact.

A bit of fly in the ointment - get into the ARP website and read their theory on "torque to yield" head bolts vs. studs or bolts that are stressed (torqued) to 75% - 90% of their yield strength and what that difference means in retained clamping pressure.

Even in that gasket picture, do you see any evidence that coolant migrated from a bolt hole to a cylinder ??? My opinion is that the open deck design coupled with a bolt that was initially torqued past its maximum clamping ability (torque to yield) is the culprit in most northstar head gasket failure. NO engine is immune to head (or any) gasket failure - but not at the rate that seems to plague the 1996 - 1999 Northstar.

Think rubber band - a bigass rubber band stretched 75% will hold a LOT longer than a thinner one stretched to 110% ("stretch to yield").

dkozloski
09-28-12, 11:12 PM
I start an engine project by going to the local DIY car wash, covering the electrical stuff with tape and plastic bags, and washing down everything before I start with the pressure washer.

maeng9981
09-29-12, 12:47 AM
I start an engine project by going to the local DIY car wash, covering the electrical stuff with tape and plastic bags, and washing down everything before I start with the pressure washer.

Would've loved to do that, but this car was not able to move on its own before the teardown. Interesting approach though, I could do that next time.

the recluse
09-29-12, 01:12 AM
I start an engine project by going to the local DIY car wash, covering the electrical stuff with tape and plastic bags, and washing down everything before I start with the pressure washer.

We used to tow the chassis down to the car wash after the engine was removed...:yup:

The rear seal is an easy remove, drill a hole in the outer edges and put a nail or nail set in it and pry, just don't nick the crank mating faces...

As far as cleaning the block, I just use a little gas with a parts washer brush along with a catch basin at the bottom...either that or mineral spirits. follow that up with a can of carb cleaner and you can get the thing gleaming...

My motor looked just as bad if not worse...

http://i1015.photobucket.com/albums/af274/therecluse_album/Photo0291.jpg

But after cleaning method described above...look at the block sides...

http://i1015.photobucket.com/albums/af274/therecluse_album/Photo0301.jpg

After it was reassembled:

http://i1015.photobucket.com/albums/af274/therecluse_album/Photo0316.jpg

Mind you, I didn't do a complete tear down, but you get the idea...

mtflight
09-29-12, 02:35 AM
I didn't "imply" anything - I stated a fact.

A bit of fly in the ointment - get into the ARP website and read their theory on "torque to yield" head bolts vs. studs or bolts that are stressed (torqued) to 75% - 90% of their yield strength and what that difference means in retained clamping pressure.

Even in that gasket picture, do you see any evidence that coolant migrated from a bolt hole to a cylinder ??? My opinion is that the open deck design coupled with a bolt that was initially torqued past its maximum clamping ability (torque to yield) is the culprit in most northstar head gasket failure. NO engine is immune to head (or any) gasket failure - but not at the rate that seems to plague the 1996 - 1999 Northstar.

Think rubber band - a bigass rubber band stretched 75% will hold a LOT longer than a thinner one stretched to 110% ("stretch to yield").

Interesting, and worthy hypothesis but are the 1993-95 torqued differently? IIRC, the headbolts are torqued at the factory by a machine all at the same time, so unless the metallurgy is inconsistent--what would cause a bolt to be torqued past it's prime?

From looking at the failed headgaskets with torn up material over the water jackets... and seeing some of these close-up photos depicting the nice metal rings around the cylinders, it looks like the 4 rings are siamesed, but the metal does not continue throughout the gasket. The rings are floating, held in place by the gasket material. There aren't any bolts holding the rings down, except the 10 headbolts on the gasket perimeter.
I recall AJ and perhaps others mentioning the head gaskets "bunching up" from the thermal cycling and combustion. I think it was yet another observation, that just looked too conspicuous to pass.
That said, IF, the headgasket materials around these metal firing rings corrode, disintegrate, or tears, or "bunches up," or get structurally compromised in any way (OAT vs. silicone rubber or nylon 6,6)... those rings would no longer be guaranteed to stay in place... would they? They could slide around and eventually the combustion gases could find their way into the coolant (and viceversa) as the seal is lost. This would be an occasion the torque to yield would be important as then it's up to Lady Luck. That's why a multi-layer solid sheet of stainless steel with cylinder cut-outs, coated with viton seems like a "safer bet," as the cut-out rings in the mls sheets wouldn't move around once fastened down.

Any thoughts on this observation? Depending on the metallurgy, wouldn't studs yield as well? IIRC isn't there a revised set of head bolt installation that involves turning them specific degrees (yield vs torque)?

mtflight
09-29-12, 02:50 AM
We used to tow the chassis down to the car wash after the engine was removed...:yup:

The rear seal is an easy remove, drill a hole in the outer edges and put a nail or nail set in it and pry, just don't nick the crank mating faces...

As far as cleaning the block, I just use a little gas with a parts washer brush along with a catch basin at the bottom...either that or mineral spirits. follow that up with a can of carb cleaner and you can get the thing gleaming...

My motor looked just as bad if not worse...



But after cleaning method described above...look at the block sides...



After it was reassembled:



Mind you, I didn't do a complete tear down, but you get the idea...

Nice job, the recluse. That is a clean looking engine. Are the cam covers painted creamy or pearly white?

the recluse
09-29-12, 03:13 AM
Cummings beige, believe it or not...

Motor finished:

http://i1015.photobucket.com/albums/af274/therecluse_album/Photo0332.jpg

http://i1015.photobucket.com/albums/af274/therecluse_album/Photo0329.jpg

mtflight
09-29-12, 03:23 AM
Wow!

maeng9981
09-29-12, 05:24 AM
That's amazing, one heck of a clean looking engine. Wish I had a lift, things would've gone so much easier.

vincentm
10-03-12, 04:19 PM
How goes the slaying of the Northstar Beast?

Submariner409
10-03-12, 05:17 PM
Depending on the metallurgy, wouldn't studs yield as well? IIRC isn't there a revised set of head bolt installation that involves turning them specific degrees (yield vs torque)?

Studs DO NOT "yield". GM Northstar head bolts do. Studs can be reused many times, GM Northstar head bolts cannot.

Studs are seated finger tight in the block and the head bolt hardened washers and nuts are torqued to a specific lb/ft specification. GM Northstar head bolts are torqued to a small initial figure to establish a starting base, then twisted an additional XXX degrees to pull the shank of the bolt to its yield - "rubber band stretch" - point.

You install studs, you torque the nuts to a specific torque in 3 passes. Install BigSerts or NS300L Inserts and ARP studs, you torque the stud nuts to a specific figure in 3 passes. You install BigSerts or NS300L inserts and use GM Northstar head bolts, you torque to initial spec + the extra XXX degrees for bolt stretch.

Why do I specify "GM Northstar head bolts" as such ? Because they are torque to yield pieces and are useless after removal. GM Oldsmobile 455 head bolts are huge affairs and can be reused forever.

Grab a pretty good-sized rubber band. Hold it so as to remove all droop, no tension ........ now pull it to some length. Notice how the rubber band itself becomes smaller in width ??? THAT'S what happens to a GM Northstar head bolt - except the head bolt will never return to it's original shape - it's like a rubber band that has been left wrapped around the box too long. Useless.

As an aside, the entire "twist to yield" procedure may be partially responsible for head gasket failures - the very statement "Torque to yield" or "Twist to yield" implies that there is no "spring" left in the bolt(s). A tiny something goes wrong and the bolts cannot maintain clamping pressure. Tim Carroll's studs, Jake's studs, and Norm's Inserts with ARP studs will NEVER lose clamping pressure.

98eldo32v
10-04-12, 12:31 AM
Castrol Super Clean and a pressure washer are your friends. Trust them......

maeng9981
10-04-12, 12:35 AM
Well, visually telling, the #1 cylinder was the problem. Every other cylinders looked normal with carbon buildup and no coolant in it, but #1 is pretty washed away. The gasket looks far much better than what I had in my Seville, either. If you're looking at the #1 cylinder, you can see some carbon buildup going past the fire ring, indicating the possible source of the combustion gas in the cooling system.

Bank 1
http://i.imgur.com/3DIqj.jpg

Carbon track near cylinder #1
http://i.imgur.com/ITQD1.jpg
http://i.imgur.com/hx7uD.jpg

Bank 2
http://i.imgur.com/Qs62n.jpg
http://i.imgur.com/Jv12a.jpg

Bank 1 gasket
http://i.imgur.com/kqDhg.jpg

Fire ring for cylinder #1
http://i.imgur.com/X0jny.jpg

Bank #1 head
http://i.imgur.com/mg2zJ.jpg

Bank #2 head
http://i.imgur.com/sWV0p.jpg

98eldo32v
10-04-12, 06:26 PM
Ironically, the two northstars that I've removed heads off of, the number one cylinder has usually been the culprit.....

maeng9981
10-05-12, 03:36 AM
Weird, after reading that I looked at the pictures of my first head gasket repair again - and found that it was indeed the #1 cylinder that had the most amount of coolant in it with the carbon buildup looking pretty different than others.

98eldo32v
10-05-12, 05:07 AM
There is something going on in that cylinder in this motor.......

CadillacLuke24
10-05-12, 01:18 PM
Well, the blower motor for the heater is on the passenger side of the car, no? Perhaps that extra heat wreaks havoc on the #1 cylinder in cars that blow their HGs.

Just a thought.

Submariner409
10-05-12, 06:13 PM
Well, the blower motor for the heater is on the passenger side of the car, no? Perhaps that extra heat wreaks havoc on the #1 cylinder in cars that blow their HGs. Just a thought.

Wut ???

mtflight
10-08-12, 03:36 AM
Studs DO NOT "yield". GM Northstar head bolts do. Studs can be reused many times, GM Northstar head bolts cannot.

Studs are seated finger tight in the block and the head bolt hardened washers and nuts are torqued to a specific lb/ft specification. GM Northstar head bolts are torqued to a small initial figure to establish a starting base, then twisted an additional XXX degrees to pull the shank of the bolt to its yield - "rubber band stretch" - point.

You install studs, you torque the nuts to a specific torque in 3 passes. Install BigSerts or NS300L Inserts and ARP studs, you torque the stud nuts to a specific figure in 3 passes. You install BigSerts or NS300L inserts and use GM Northstar head bolts, you torque to initial spec + the extra XXX degrees for bolt stretch.

Why do I specify "GM Northstar head bolts" as such ? Because they are torque to yield pieces and are useless after removal. GM Oldsmobile 455 head bolts are huge affairs and can be reused forever.

Grab a pretty good-sized rubber band. Hold it so as to remove all droop, no tension ........ now pull it to some length. Notice how the rubber band itself becomes smaller in width ??? THAT'S what happens to a GM Northstar head bolt - except the head bolt will never return to it's original shape - it's like a rubber band that has been left wrapped around the box too long. Useless.

As an aside, the entire "twist to yield" procedure may be partially responsible for head gasket failures - the very statement "Torque to yield" or "Twist to yield" implies that there is no "spring" left in the bolt(s). A tiny something goes wrong and the bolts cannot maintain clamping pressure. Tim Carroll's studs, Jake's studs, and Norm's Inserts with ARP studs will NEVER lose clamping pressure.
Very good and illustrative post. Thank you. I suppose the stretch could be measured. Is it millimetric? Begs the question: why on Earth would the engineering team choose these type of bolts? I don't think they're cheap are they?

Also are Tim Carrol's and Jake's studs the same? Norm's use non TTY bolts like the Olds you mention?

----------


Weird, after reading that I looked at the pictures of my first head gasket repair again - and found that it was indeed the #1 cylinder that had the most amount of coolant in it with the carbon buildup looking pretty different than others.

Do you have a link to the 1st repair pics? Also how much do you know about the coolant change on either cars? I think in our discussions you mentioned the Seville had a decent coolant service history.

It does look like there's some rust and flaking around the passage holes in that gasket. Is it surprising? Otherwise the gasket looks pretty solid. No bunching up, it seems.

What's up with the # 1cylinder coincidence? Bizarre or onto something?

Submariner409
10-08-12, 09:58 AM
Head stud stretch can be accurately measured with a dial indicator. When Norm's Inserts are used with head bolts they are the OEM GM bolts, tightened according to the correct year service manual. When Norm's Inserts are used with ARP studs, the studs are inserted finger tight and the nuts/hardened washers are torqued to a specific value in 3 passes.

I don't know if ARP or anyone else makes Northstar head bolts in a good ol' straight shank torque-only monster like the Olds bolts.

Studs are torqued to a specific lb/ft value which stretches them several thousandths of an inch = clamping pressure. Read the theory in the ARP site. "Torque (or tighten) to yield" bolts are, by definition, tightened very close to the limit of their metallurgy strength - much more and they break, which is why you DO NOT re-use the Northstar head bolts during top overhaul.

Regardless of supplier/manufacturer I would imagine that Northstar stud packages are designed and machined from stock that is more than adequate in tensile strength specs. (ARP studs are treated to tensile strengths approaching 180,000 pounds. Sufficient.)

........... In the head gasket pictures - the #1 cylinder with the cylinder leak past the fire ring. The gasket material itself looks shiny and well compressed. How much "meat" is there in the cylinder head area just over that water passage/gas leak area ??? ......... Where I am going: Did the cylinder head "bow up" at that end, between the head bolts, and allow gas to blow by ?

drewsdeville
10-09-12, 11:19 PM
Begs the question: why on Earth would the engineering team choose these type of bolts? I don't think they're cheap are they??

I'm not sure Sub really touched on WHY they work as much as HOW they work.

They use these bolts now because todays engines demand more precision. Everything is aluminum now, and expansion and contraction rates are much higher than with old iron engines. With everything moving around so much, it all needs to "slide" on the gaskets to retain the seal without interrupting the integrity. This is where torque to yield bolts come in. They provide a much more accurate and even torque across the entire head, allowing the greater expansion/contraction rates to occur without tearing up, pinching, or otherwise destroying the gasket.

Submariner409
10-09-12, 11:39 PM
Nice try.......... but there may be other factors here.........

In that scenario, the aluminum engine parts slide around ??? If the block and heads expand (swell) with heat and the steel bolts don't (or to a lesser degree) then why doesn't clamping pressure increase with heat vs. decrease ?? (and why don't the cast-in iron cylinders pop away from the block ?) If the block and heads changed geometry to any degree, what would then happen to crank, rod, and cam bearing alignment ?

Do ANY of the posted gasket/head/block pictures show evidence of parts sliding around ?

Something else is going on here and it's not the aluminum engine - there are too many examples of aluminum and aluminum/iron engines working perfectly satisfactorily. (It's all mechanical - it ain't forever)

drewsdeville
10-10-12, 02:16 PM
I think you misunderstood - my post wasn't aimed directly at the N* and it's problems - it's just a summary of changes made in modern engines (most of todays engines use TTY bolts - not just the N*). He asked why a manufacturer would choose to use TTY bolts

Modern headgaskets are coated with teflon, silcon, and other anti-friction materials for a reason, and it's not because everything stays perfectly in-place. If everything was clamped down rock solid with no movement, all we would need for a head gasket is a simple piece of stainless steel. No layers, no coatings, no nothing. Hell, with todays manufacturing processes, we wouldn't even need head gaskets - just machine the surfaces perfectly flat and bolt them down with 500 ft-lbs.

This is exactly the reason why you can see the scrubbed gaskets in "normal" head gasket failures.

If the block and heads expand (swell) with heat and the steel bolts don't (or to a lesser degree) then why doesn't clamping pressure increase with heat vs. decrease ??

It does, to a degree.

(and why don't the cast-in iron cylinders pop away from the block ?).

They have, in some engines. On a related note, what usually happens first is the valve seats drop out of the head. This is a very common failure on engines that have been overheated. Since the seats are generally a press fit from the factory, and failure occurs mainly at high temps, this is good supporting evidence that thermal expansion/contraction is a major player in close-tolerance engine parts.

If the block and heads changed geometry to any degree, what would then happen to crank, rod, and cam bearing alignment ?

This has also been an acknowledged problem in some engines. GM's 4.X series is one of them.

Submariner409
10-10-12, 02:22 PM
I'll buy some of that ^^^ but throw a hook in there.......... I have used steel sandwich (MLS) head gaskets in Olds 455 engines and not had a problem for years - in a salt water environment (the engines are fresh water cooled - sealed coolant system with heat exchanger).

It would be interesting to find out if a member had ever coughed up the $125 (apiece ?) for the Cometic Northstar MLS gaskets.

mtflight
10-10-12, 02:26 PM
I'm a big proponent of the mls experiment if only for the fact they're one piece (many layers) and the blow rings aren't floating in the composite material. If I have to get a hg replaced it will be mls. The Viton coating is resistant to OAT but I'd be using conventional green anyway.

Edit: IXSLR8 has used Cometic http://www.cadillacforums.com/forums/search.php?searchid=801211

98eldo32v
10-10-12, 03:48 PM
http://www.ebay.com/itm/COMETIC-HEAD-GASKETS-CADILLAC-NORTHSTAR-4-6L-/370357830017?_trksid=p4340.m1850&_trkparms=aid%3D222001%26algo%3DSIC.CURRENT%26ao%3 D1%26asc%3D11%26meid%3D2647635065542443229%26pid%3 D100011%26prg%3D1005%26rk%3D1%26sd%3D310427795970% 26

I find this conversation about the headgasket for the Northstar very interesting, especially pertaining to the MLS headgasket.

Yes, I can say you're going to pay a bit more for them, but in reality the factory headgasket has proven itself for a life expectancy for a range of 80k or better depending on a number of factors, maintainence of vehicle etc.

I can only say from the headgaskets that I've removed from the Northstars that I've disassembled that used Dexcool for coolant that were well maintained to a range or poorly maintained. We're dealing with a multi faceted problem.

The thread pitch on the bolts are too fine, the bolts "stretch' to some degree. The "open" deck block design, could be contributing to the headgasket issues. The expansion rates of the metals coupled with the combustion ratio could be a factor also. The Dexcool issue, well that can go on forever, but my personal experience with it it's poison to intake and headgaskets.

I've only had one expereince so for with a MLS headgasket and it wasn't on a Northstar.

I had to work on a 00 Dodge Intrepid R/T 3.5. It unfortunately jumped time and wiped out the intake valves. Therefore the heads had to be removed. Upon removing the heads I never knew this motor used a MLS headgasket, but it was a pleasant surprise.

After the heads were off, there was almost no cleaning of the heads or deck surface of the engine block. The gasket is basically a flexible shim, that if I didn't know any better you probably could have reused it. Yet, I'm not that crazy to go that deep into a motor and chance something like that, but it came off the motor that clean.

The price of the gasket kit, well that was another story. It was a bit pricey, but what you saved in clean up time and the gasket looks virtually indestructible was priceless.

I'm on the fence about using the MLS gasket on my Northstar, but from what I've seen from personal experience, I'm leaning that way.

I just think during the Northstars design to production, some corners were unfortunately cut to save the usual, $$$$$$.

The motor is too nice of a motor to suffer some of the ills that it has. If you ever get one to really run nice, you'll be extremely happy. That too I can say from experience. I look forward to rebuilding my eldorado motor.

Good luck gents

mtflight
10-10-12, 08:19 PM
I read somewhere that GM was one of the last manufacturers to go MLS route--they took their time to get there. As far as Dex, why do the 93-96 have significantly lower failure rates (the fewer ones may indeed be neglect to change the green silicated coolant every couple of years). We can agree that corrosion is a factor, and some well-maintained systems on DEX have it too. MLS would be much more resistant to corrosion, and the shim design prevents discrepancies of the composite gasket between the cylinder bore rings and the remaining gasket material (floating).

The only argument for using the factory style gasket is that it works as well as it does, sometimes corroding, sometimes flaking, sometimes failing.

98eldo32v
10-11-12, 12:32 AM
The only true argument for GM NOT using the MLS gasket on their hi-tech Northstar was to save $$$. You take a nickel or a dime here and there multiply it by a million or so engines, add that up. Don't say save a dollar......

The factory gasket performs well under the circumstances, at least to get the car out of the factory warranty period. After that, throw the car basically away or prepare to fix it at your own cost.

It's a shame because the engines and the cars themselves are nice.

Submariner409
10-11-12, 10:23 AM
The factory gasket performs well under the circumstances, at least to get the car out of the factory warranty period.

That argument doesn't hold water because there are millions of 40 year old engines, worldwide, that are still running around with their original felt/graphite/steel mesh/coated original head gaskets.

Every year, for the past 22 years, I have taken apart (for rebuild) Olds 455 and GM454 engines from the 70's to use as marine workhorses. I can safely say that I have NEVER seen a failed head gasket in a stock GM built big block - even in engines with broken off head bolts ! Worn rings, pistons, cams, lifters, valves, chains - yes. Head gaskets - NO.

The Northstar cylinder leak bugaboo is something other than the head gasket itself - and even then the failure percentage is, in the order of things, insignificant. (No, it's not insignificant to the owner of a leaking engine - but just how many million Northstar engines are out there ?)

98eldo32v
10-11-12, 10:55 AM
"That argument doesn't hold water because there are millions of 40 year old engines, worldwide, that are still running around with their original felt/graphite/steel mesh/coated original head gaskets."

I can argee to that statement, but the Northstar isn't one of them.

You have "supposedly" a technical advanced engine that refuses to retain a headgasket over some "poorly" designed bolts, and/or some coolant that was never "tested" throughly for it's corrosive properties with other materials.

No motor is perfect, but if you can make a statement of 40 year old motors and technology has advanced since then, are you saying the engineers 40 years ago were smarter than the ones now? I truly hope not.

This is more bean counting measures that the consumer in some shape or form turns into the guinea pig.

Let's not go back to the TRUE darker days of GM. 2.3 quad 4's loosing headgaskets, 4100's/ V8/6/4, that weren't nothing but boat anchors, paint peeling off of cars because the primer that was used was never tested with the paint for proper adhesion. The list goes on.

I worked for GM during those ugly times. I truly loved their cars, great idea's, but poor execution of the idea's. I used to scratch my head and wonder what was going on, only years later when I talked to some engineers, it all made sense.

The engineers idea's started out one way with certain specifications and materials, the final product ended up ANOTHER way thanks to bean counters. That's just nature of the beast.

You keep pinching too many pennies, now you're pinching into your reliability of your car. Who wants to drive a car that's unreliable?

If I shell out the money for GM's top of the line vehicle, I EXPECT top of the line performance and reliability. If I shell out money for a chevette, then I get what I pay for. That USED to be the saying, "You get what you pay for". There is no way someone should shell out Cadillac money and get Chevette reliability.

That's bad business. Period.

drewsdeville
10-11-12, 02:21 PM
I'll buy some of that ^^^ but throw a hook in there.......... I have used steel sandwich (MLS) head gaskets in Olds 455 engines and not had a problem for years - in a salt water environment (the engines are fresh water cooled - sealed coolant system with heat exchanger).


Thats not a hook, that's support. Those are iron engines, not aluminum. The coefficient of thermal expansion on an iron engine is SIGNIFICANTLY lower than an aluminum.
Like you said, 40 years ago, head gasket leaks were virtually unheard of, even when overheated. Today, as we pump out aluminum products almost exclusively, gasket failures are relatively common, across all manufacturers (some worse than others, of course).

mtflight
10-11-12, 03:07 PM
"That argument doesn't hold water because there are millions of 40 year old engines, worldwide, that are still running around with their original felt/graphite/steel mesh/coated original head gaskets."

You have "supposedly" a technical advanced engine that refuses to retain a headgasket over some "poorly" designed bolts, and/or some coolant that was never "tested" throughly for it's corrosive properties with other materials.

This is more bean counting measures that the consumer in some shape or form turns into the guinea pig.

Let's not go back to the TRUE darker days of GM. 2.3 quad 4's loosing headgaskets, 4100's/ V8/6/4, that weren't nothing but boat anchors, paint peeling off of cars because the primer that was used was never tested with the paint for proper adhesion. The list goes on.

I worked for GM during those ugly times. I truly loved their cars, great idea's, but poor execution of the idea's. I used to scratch my head and wonder what was going on, only years later when I talked to some engineers, it all made sense.

The engineers idea's started out one way with certain specifications and materials, the final product ended up ANOTHER way thanks to bean counters. That's just nature of the beast.


That's bad business. Period.

With the Northstar being so reliable as far as ring and piston and overall engine wear, the missing piece is a reliable head gasket.

While the failure rate of the headgasket some claim is "insignificant" as far as percentage, it is enough to give the engine line a reputation of having cooling system issues. People that haven't owned them have heard stories or know someone who has had issues with headgasket or "bad heads" as I've heard some say. It's an issue to the used car lots as well. It's enough of an issue that anyone who is aware and is in their right mind does some research prior to purchasing one.

If the issue is clamping force, the studs should take care of that, but do bad bolts rust a head gasket? With the thermal properties of aluminum being what they are, there is a lot more demand on the head gasket, so the old school gasket does not work too well, does it?

As far as the errors that GM made in the past, such as not testing primer with paint or the V8/6/4 etc, the undeliberate OAT coolant experiment sounds like it is not far fetched at all. But, in light of the clamping issues and the piss-poor headbolt assignment and overall head gasket failure issue--why do the 93-96 have significantly fewer headgasket issues? Sure there are many ways to ruin a headgasket (overheating, no cooling system maintenance, a porosity mishap/manufacturer defect, etc).

But back to 93-96, the issue could be that simple, and a neglected failed gasket could make it look to be much more complicated than it really is (waiting for all hell to break loose causing collateral damage to the bolts. etc.).

Submariner409
10-15-12, 09:16 AM
If the issue is clamping force, the studs should take care of that, but do bad bolts rust a head gasket? With the thermal properties of aluminum being what they are, there is a lot more demand on the head gasket, so the old school gasket does not work too well, does it?

No, "bad bolts" do not rust a head gasket.

If the issue truly was different expansion rates of parts, then the idea of using a Cometic MLS head gasket is doomed from the start: they are essentially solid steel/copper and once torqued to spec they are solid metal - while a good ol' FelPro head gasket flexes a few millionths of an inch, a MLS gasket will not............. So where does that leave the "uneven expansion" theory ?

drewsdeville
10-16-12, 10:43 PM
Might be a good read for you Cometic MLS guys - no opinion intended or implied - just passing on an article I read last fall.

"MLS—The New Standard
MLS head gaskets have been out for several years now, and they've gone from exotic components for only the most high-end race motors to standard equipment on just about everything from Street Stock engines to Cup motors. "MLS" stands for Multi-Layer Steel and refers to how these gaskets are constructed. Unlike a more traditional composite gasket which uses different materials pressed into one solid gasket, an MLS gasket is constructed of three or more pieces of steel that are only attached together at a few points, typically by rivets.


But the most interesting aspect of the MLS design isn't the number of layers of steel it uses, but what is done to the two layers on the outside of the gasket. A bead is rolled, or embossed, into the steel that goes around the cylinder bores as well as the water passages and even the oil drain back holes between the block and heads. When the cylinder heads are bolted to the block, the gasket is compressed but the sealing beads aren't crushed flat. It's these beads that provide the seal. And in the event combustion pressure causes the head to lift off the block slightly, the beads are able to spring back a bit so that the seal is maintained between the block and heads.


"There are actually many differences between our MLS gaskets and composite gaskets offered by other companies," explains Kevyn Kistner of Cometic Gasket, one of the leading manufacturers of MLS gaskets in the industry. "The most noticeable difference is the materials used in each design. Cometic's MLS gaskets utilize multiple layers of embossed 301 stainless spring steel which can withstand the constant abuse provided by today's high-performance and race engines. By utilizing this design we take advantage of an active seal that is capable of sealing even when a cylinder head starts to move around.




Read more: http://www.circletrack.com/enginetech/ctrp_1108_racing_head_gaskets/viewall.html#ixzz29W5H4aa0




"

Submariner409
10-17-12, 09:33 AM
Yep - I have that article and paragraphs in my files. I took that into consideration when I posted the query on the MLS theory for the Northstar. If you'll look at the Northstar Cometic MLS gasket, it's quite sophisticated.

.........but I still want to get away from the idea that Northstar heads "slide around" (they do each have two pretty healthy dowel pins) - I maintain that the original bolts, as used, can't do the job over time, so perhaps, in conjunction with studs, the MLS would be the way to go.

(Yes, my post implied that the gaskets, once crushed, are pretty incompressible - that's based on pulling apart the Olds engines for valve jobs and looking at the MLS gaskets used. No, I don't currently have an example in the shop.)

mtflight
10-17-12, 03:28 PM
.........but I still want to get away from the idea that Northstar heads "slide around" (they do each have two pretty healthy dowel pins) - I maintain that the original bolts, as used, can't do the job over time, so perhaps, in conjunction with studs, the MLS would be the way to go.

I've been intrigued by this, and have been studying the situation. The information you have shared on the design characteristics of stretch to yield bolts has convinced me that the head bolts are definitely a weakness of the engine design as a whole.

The fire rings in the composite head gasket are only held in place by friction of the head bolts on the Z axis (up down).Said dowels hold the gasket material in place and the gasket material holds the rings in place on the X, Y axis (flat plane).

Once the integrity of the gasket material around the open deck water jacket becomes compromised, the siamesed fire rings in the gasket are more likely to let blow-by gases into the water jacket. There is usually some tell-tale sign that this has happened, and it is usually paired with lack of gasket integrity (eg, a tear, a hole, flaking, rust, etc).

http://i224.photobucket.com/albums/dd25/AJxtcman/Northstar/222.jpg

I am not sure about the sliding of these rings, but AJ has mentioned bunching up of the head gasket in the waterjacket area, possibly indicating that the ring unit does break loose in some way and beats to its own drummer--at that point there would be cooling system pressurization and possibly coolant spilled into the bolt holes. I see a connection between the material that holds the siamesed rings in place on the 2D XY axis.

We have seen the composite material in these head gasket disintegrate or crumble in the waterjacket area, sometimes in cars with alleged "good cooling system maintenance", sometimes appearing rusty or cardboard-like. This situation occurred less on the 93-96 iterations of the same engines, possibly having to do with gasket materials being better protected when coated with silicates, at least during the 2-year timespan between scheduled coolant changes. Those engines devoid of coolant exchanges are most likely the ones that account for the majority of existing failures of those years--suffering exactly the same way the 97 and up do.

I therefore agree that studs in conjunction with MLS would most likely solve the riddle from reoccurring. In reading the article it seems that the surface finish is imperative when installing the MLS. Would scraping suffice, or how would one go about resurfacing them as best as possible?
http://i66.photobucket.com/albums/h267/mtflight/etc/X06PT-PP045.jpg
MLS gaskets are multiple layers of the same pattern. The dowels would hold the cylinder cutouts in place versus the OE gaskets that have "floating" rings that are subject to the integrity of the rest of the gasket materials, which are subject to many stressors and oxidizing in the coolant/water mix. Good cooling system maintenance is, of course, one less factor to worry about.

Tom's Caddy
10-17-12, 05:09 PM
Great thread guy's, my question is, could the motor mounts be a result with this problem. In regards to the thread with gasket material bunching and the rings moving, at that point due to engine torque. I know people have replaced lots of bad motor mounts on this board. My DTS has a new redesigned motor mount I believe. I hope it has solved the motor mount issue, if anybody knows of replacing a motor mount on a 2006-2011 please let me know. All the best.

mtflight
10-17-12, 06:26 PM
could the motor mounts be a result with this problem. In regards to the thread with gasket material bunching and the rings moving, at that point due to engine torque.



Nice DTS. the gasket issue is completely internal to the engine and so in a different dimension than the mounts. If the mounts were holding on to the engine heads then maybe, but I doubt it.

That would be a most surreal scenario. One way to decrease the stress on the engine mount, is to gently ease into the throttle when moving from a standstill, so that the stress is more linear--versus a quick strong jerk.

CadillacLuke24
10-17-12, 07:00 PM
Tom's about the most proactive owner I've evern seen :D

Motor mounts will take awhile to go bad, and you'll be able to tell. I think you can hear a clunk on acceleration, and when you brake torque the engine, it will jump.

Submariner409
10-17-12, 07:50 PM
mt, felt/graphite head gasket material over/across ANY coolant passage/hole/steam hole in ANY engine looks like pure dog doo after so many years in contact with coolant. Old head gaskets that come off 1970's (or even a recent 1964 283 Chevy) are, ummmmm, impressive. Any portion in contact with coolant is a real spongy mess and the compressed portions are as brittle as eggshell.

I don't feel that the bulged parts in the Northstar gaskets are contributory - the bulged parts are the normal result of hanging toilet paper out in the rain too long. The squashed, compressed, clamped areas are where we're looking.

In no picture in N* Performance to date have we seen where coolant has migrated through the compressed gasket to a cylinder; we have seen where coolant has passed over/around the gasket and/or fire ring - loss of head bolt clamping pressure, and, as DD pointed out, the inability of the stretched head bolts to "roll with the punches".

TC, it's very doubtful that a broken front center motor mount would contribute to head gasket failure. To muddy that water, there are those who question the wisdom of the Eldorado torque strut mounting to the left (front) cylinder head: Every time you call upon the engine for max output at max rpm that's another 300 lb/ft of torque applied to the left head - and it doesn't seem to make the Eldorado any more or less prone to head gasket failure.

mtflight
10-17-12, 10:26 PM
hey sub.

So these gaskets always look that bad? It's a miracle they seal as well as they do. Maybe they are just not apt for this type of metal alloy and power output. The cheap bolts don't help.

Basically you're telling me that we have a modern, high tech, high feature, aluminum long block, aluminum heads engine with a very old-school, old technology, outdated, composite felt/graphite head gasket. I assume the short term testing was extensive and it passed without issues, simulating many years of use. I wonder if they have any way to simulate the aging of the engine with old coolant? Or better yet, to have one of those look-like-poop gaskets ensure reliable head gasket sealing over time. That's probably where the engineering team had a lapse of judgement--it passed the short term simulations, and they assumed it would hold up like it does in any other iron block. Then they changed the coolant on the experiment, at the end of 96 and oh there's a little spike in head gasket failures right after. Time to redesign that seal with coarser and longer bolts... then again with more coarse bolts...the we will get it right eventually approach.

I was under the impression that reliability in sealing the heads has been noted to be more critical in aluminum alloy engines than it is in iron block engines...something having with to do with metals expanding and contracting at different rates.

I think the Northstar engine came with a prescription for a different type of gasket,one that is on par in technology. One could argue that MLS gaskets weren't common yet. However I read that GM has been one of the last big manufacturers to catch up to the times in finally using MLS gaskets. They finally figured it out by the time they put out the LC3 Northstar: match the gasket to the high sealing requirements relative to the output of the engine. Was this a page in the book about the dinosaur days of GM?

Ranger
10-17-12, 10:27 PM
If the mounts were holding on to the engine heads then maybe, but I doubt it.

My right torque strut is mounted to the front head.

Submariner409
10-18-12, 09:57 AM
I said nothing that would indicate that basic head gasket technology had not kept up with engine design over the years - I said that felt-graphite-whatever head gasket material, in contact with coolant for long periods, looks nasty. Head gasket manufacturing technology has not changed radically over the years - the basic system works and works well if the cylinder head is securely held to the cylinder block. Yes, some head gaskets use Teflon coatings or some such - but the basic gasket appears to be the same as 25 years ago. Look at the CF pictures of different Northstar overhauls - see any exotic gasket materials there ?

If a portion of the gasket material is in contact with coolant/a cooling passage it has nothing to do with sealing a cylinder - it's simply excess material hanging out in the breeze. The compressed areas of the gasket form the "seal" - the uncompressed areas are simply along for the ride.

Alloy and power ????? The Northstar is a little engine in terms of pure size and NA power - any kid on the street can hand-build a Chevy 327 that will eat a Northstar alive for power and torque, an use cheap good ol' JC Whitney FelPro gasket sets to do it. The 1967 Corvette 427/435 actually put out just over 500 hp and the whole engine was assembled with paper, cork and felt gaskets - there are still original 427's running today. I daresay that you and I both have several square feet of cork and paper gasket materials in our shop drawers.

It's not the gaskets in and of themselves - it's the bolts, the threads, the open deck, and the siamesed cylinders that don't support the gasket in doing its job.

EDIT: "Power" - The Northstar is a 279 C.I. small displacement high-winding engine. The old Chevy 283 is almost the same C.I. in an OHV pushrod configuration. Given the time and proper parts, a roller cam NA 283 can be built that would easily surpass the VIN 9 Northstar "power" (and torque) by over 50%.......... and not blow head gaskets............but 283's and 327's are disappearing - everyone's building the later 350 version of the SBC.

Tom's Caddy
10-18-12, 11:31 AM
Thanks mtflight, I love my DTS. I still think some people on this board that say the motor mount issue could be a contributing factor could have something there. I`m told by my Cadillac dealer and many people on this board, including my owners manual to WOT my DTS often. They give many benefits for this. And it is lots of fun. Sorry to some of you out there but I only use Dexcool but, stongly believe it is poison if not changed very often. There is a thread on this, from a former GM employee on this matter a good read. I use it because it is the best for aluminum, but on seals and gaskets it is very bad if left in to long. 1. Old Dexcool 2. bolts (shorter less course threads) 3. maybe gasket production 4. motor mounts 5. transverse motor. All this after years of WOT would cause failer in any engine, my 2 cents. All the best everybody.

98eldo32v
10-18-12, 11:37 AM
"So these gaskets always look that bad? It's a miracle they seal as well as they do. Maybe they are just not apt for this type of metal alloy and power output. The cheap bolts don't help.

Basically you're telling me that we have a modern, high tech, high feature, aluminum long block, aluminum heads engine with a very old-school, old technology, outdated, composite felt/graphite head gasket."


WELCOME TO BEAN COUNTING 101 /COPORATE LEVEL.

Submariner409
10-18-12, 01:31 PM
I love my DTS.

You might want to go way up ^^^ to the top black bar and study the entire Cadillac Technical Archive (speaking of articles by Cadillac engineers.............)

Nothing wrong with properly maintained DEX-COOL.

WOT with bad engine mounts is plain folly. Things break then - big time, and it's not head gaskets.

mtflight
10-18-12, 01:56 PM
Nothing wrong with properly maintained DEX-COOL.

on a Northstar engine, per the manufacturer's instructions? 150,000 miles or 5 years?

Submariner409
10-18-12, 02:03 PM
I, personally, would not go that far/long, but there are hundreds of thousands of engines out there that do .............. Not every car owner is as paranoid/fanatic as our crop of CF members................

98eldo32v
10-18-12, 02:07 PM
on a Northstar engine, per the manufacturer's instructions? 150,000 miles or 5 years?

:cookoo: I WOULDN'T EVEN DREAM OF TRYING THAT.

THE HEADGASKETS BARELY SURVIVE HALF THAT MILEAGE........

mtflight
10-18-12, 02:33 PM
I said nothing that would indicate that basic head gasket technology had not kept up with engine design over the years - I said that felt-graphite-whatever head gasket material, in contact with coolant for long periods, looks nasty. Head gasket manufacturing technology has not changed radically over the years - the basic system works and works well if the cylinder head is securely held to the cylinder block. Yes, some head gaskets use Teflon coatings or some such - but the basic gasket appears to be the same as 25 years ago. Look at the CF pictures of different Northstar overhauls - see any exotic gasket materials there ?

If a portion of the gasket material is in contact with coolant/a cooling passage it has nothing to do with sealing a cylinder - it's simply excess material hanging out in the breeze. The compressed areas of the gasket form the "seal" - the uncompressed areas are simply along for the ride.

Alloy and power ????? The Northstar is a little engine in terms of pure size and NA power - any kid on the street can hand-build a Chevy 327 that will eat a Northstar alive for power and torque, an use cheap good ol' JC Whitney FelPro gasket sets to do it. The 1967 Corvette 427/435 actually put out just over 500 hp and the whole engine was assembled with paper, cork and felt gaskets - there are still original 427's running today. I daresay that you and I both have several square feet of cork and paper gasket materials in our shop drawers.

It's not the gaskets in and of themselves - it's the bolts, the threads, the open deck, and the siamesed cylinders that don't support the gasket in doing its job.

EDIT: "Power" - The Northstar is a 279 C.I. small displacement high-winding engine. The old Chevy 283 is almost the same C.I. in an OHV pushrod configuration. Given the time and proper parts, a roller cam NA 283 can be built that would easily surpass the VIN 9 Northstar "power" (and torque) by over 50%.......... and not blow head gaskets............but 283's and 327's are disappearing - everyone's building the later 350 version of the SBC.

I understand what you're saying, and it's cool stuff. However aren't those engines you mention iron blocks? I'll bet they also have a closed-deck design with a smaller area in contact with coolant?

As I said, I'm sure the Northstar passed the rigorous stress tests with that gasket. But it appears to fail the real world test of time, more often that we would like to hear. Newer designs move away from those gasket materials. The modern HO engines that GM is putting out today have MLS gaskets, probably for a good reason.

The Northstar engine design calls for a better gasket, that is hard to argue. It is a combination of factors, aluminum heads and longblock, open deck with a very close proximity to a large area that soaks the gasket in coolant that admittedly does not get along with the felt gasket very well. Add stretch to yield bolts to that formula and you have to walk the fine line with lady luck because HG failures are not only limited to neglected cooling systems. Maybe if the vast coolant passages weren't so close to the fire rings the story would be different--but this isn't about what the engine isn't, it's about what it is. The head gasket's fire rings are an island literally surrounded by coolant that is deteriorating the felt and possibly graphite component in them.

I wouldn't discard the Dex-Cool vs conventional green coolant argument, because otherwise, what makes 93-96 Northstar's have better "luck" with the head gaskets? The typical advertised pH of Dex-Cool is lower than traditional antifreeze/coolant (8.3 vs 10.5). The pH level is very close to that of sea water, typically pH 8. Conventional green typically has a pH of 10.5 pH. So it's possible that the lower pH contributes or enhances the deterioration the "wet" part of the gasket, which you say factually, has nothing to do with the seal of the headgasket in the compressed areas. Fluids do tend to permeate felt, however, so I am not so sure why your'e so confident about the compressed area staying dry? Furthermore, heat enhances the permeability of water, and the lower coefficient of viscosity of ethylene glycol in there further facilitates permeation of the felt materials and fabrics. Is this ideal, in sealing two critical hot aluminum surfaces over time? *NO*

Then there's potassium 2-ethylhexaonate and it's ability to dissolve nylon 6,6 and natural silicone rubber, and the lack of silicates which typically coat and protect other materials besides alloys by competing with more harmful corrosive oxides.

So I don't deny that organic acid technology coolants are fine for copper, brass, cast iron, steel and aluminum but to be safely deployed in different applications with other materials one would have to test them with other materials such as the felt in the head gasket, which will be soaked in the case of the N*.

No issue with OAT and an MLS gasket but not so sure about with a felt/graphite composite gasket. Silicates are used to coat carbon and therefore graphite and protect it from other oxides and thus deterioration. There are no silicates in Dex-Cool--so what's protecting the graphite?

Below is the head gasket of the LS9 engine.
http://i66.photobucket.com/albums/h267/mtflight/etc/X09PT-EP033.jpg'

Edit: after writing the details about graphite being protected by silicates, and coolant with its low viscosity coefficient soaking into the felt gasket, it makes sense that better clamping would better isolate the compressed, wishfully "dry" area of the gasket from disintegrating [failing]. At least it would buy it some time. This is probably why the bolts became longer, and then coarser over time. Still I believe the missing silicates are helpful in protecting the integrity of the felt/graphite composite gasket.

CadillacLuke24
10-18-12, 03:35 PM
Pete and RePete were on a fence. Pete got knocked off with a baseball bat.

WHO WAS LEFT?

98eldo32v
10-18-12, 03:53 PM
MtFlight,

I'm going to say this and this is just my opinion nothing more.

This has been an EXTREMELY informative post on the dex-cool, head bolts, and open deck design of the northstar engine block. With the wealth of information in this post alone, I've decided to go the MLS route for my headgasket job on my eldo.

I "was" on the fence, but now I'm convinced that this is the correct way to approach this issue. Everyone knows by now this isn't a user friendly engine to work on, so why set myself up for a "possible" mishap down the road.

Yes, the studs and the inserts have proven themselves to repair the bolt issues, but the gasket and dexcool issues remain. I'm going to alleviate all the possible culprits. Block will be studded, MLS gasket will be used, green antifreeze is going in..........done.

Ironically, all the info posted here, are you saying the engineers didn't have this info at the time of the development of the northstar engine? Or was this the case of "we"ll just use what has been getting by all along" ,it'll hold together.

Tom's Caddy
10-18-12, 04:46 PM
Hi Submariner409, I think you pick and choose what to read on a thread. I said if you change the Dexcool VERY OFTEN I think that covers properly maintained as you put it. Was there not legal action taken against GM over Dexcool? I have had all GM vehicles = 8 in total and had cooling problems with 7. Love GM not knocking them I don't even want to go there to relive the past. By the way my daughters taught me how to post pictures so I post a picture with a thread it seems they are vanishing. I wonder if someone on this board doesn't like looking at Cadillacs?
http://i1271.photobucket.com/albums/jj621/tomscaddy/8abbe4e8.jpg

Submariner409
10-18-12, 05:21 PM
Several people (not just me) are tired of looking at the same blurry Deville over, and over, and over. Make a picture album and post a slew of decent pictures there - that's what the Community tab is for instead of taking up server space in the daily threads. FWIW, I look at Cadillacs every day, all types, and never get tired of the scene.

Staff is here to keep this place clean, speedy (as possible) and act as field umpires. Things get overly dicey, it goes to Admin and it's out of our hands.

You are a full-fledged CF member - if you don't like the way the site is run from the field, you are free to read the Forum Rules and Guidelines down in Site News and post a complaint to Admin in the Site News Forum.

Everyone has their pet opinions on DEX-COOL as well as other fluids - No one is knocking your "change it frequently" procedure - matter of fact, I am a staunch proponent of changing coolants at least every 3 years......................Post #60, Post #58, and several hundred other coolant posts since early 2006.

mtflight
10-18-12, 05:25 PM
Thank you for the good words, 98eldo32v. My HG is holding so far, and I've only been running silicated green for a few months. Silicated coolants almost immediately coat the surfaces they are in contact with, so they offer instant protection against corrosion. The way the hexanoic acid (organic acid technology, extended-life coolant) variety works, is different, and I've read it takes a few thousand miles to begin offering protection.

I should note that color is just a dye nowadays, so make sure it is "conventional" silicated coolant if you're after the carbon graphite protection in the head gasket. It probably won't matter what coolant you use once you have MLS head gaskets. The Cometic MLS gaskets have a viton coating (fluoroelastomer) which is also used to make chemical-resistant gloves for labs etc.

Tom is correct, in that the hexanoic acid that comprises the anti-corrosion package in Dex-Cool was responsible for the catastrophic failures in intake gaskets for a few engines a few years ago because they had nylon 6,6 in them, which culminated in the large class-action lawsuits. I think hexanoic acid is also responsible for many of the the leaking water pump cover gaskets, and any other failed silicone rubber gaskets that come into contact with coolant. Take note that most revised gaskets in the later years are made of other polymers that are resistant to hexanoic acid, thus they had no further issues in the later years of production. *edit: and Tom, I guess I wasn't going crazy thinking your car was there, and then it wasn't. I thought it had something to do with me using the iPhone cadillac owners app.*

If my HG fails on my 99 ETC (It did on my 98 at 116K a few years ago), I too would do exactly what you've decided: Studs with MLS gaskets. I don't plan to neglect my cooling system so I'll still be using conventional green as well, and changing it once a year. Thanks again for the kind words and I look forward to reading about your studded MLS-equipped Eldo. There's another member here that has gone with MLS, but I can't remember his name.

I have no idea what the engineers did or did not know. It does seem like there was a strong effort to make cars that were very low maintenance, thus the extended life coolants, the OLM, the platinum spark plugs, etc were part of the effort. I think a lot of it was experimental and either there wasn't time to get a lot of homework and testing and research done or there wasn't enough of a case to present to the "penny counters" to justify the decisions to go with more modern but costly parts? I don't think this was a deliberate boo boo. I agree with your ideas that it corporate may have been involved--they weren't doing very well so they had their reasons. If they were all quality and reliability, then our cars would be like Rolls Royces, and would cost a helluvalot more.

Submariner409
10-18-12, 05:43 PM
Remember: Suspended silicates in good ol' green coolant have been radically reduced in order to lessen water pump shaft seal wear - most 'green' coolants are now "no silicate" or "low silicate" formula.

Tom's Caddy
10-18-12, 06:05 PM
Thanks for you're honesty sub you won't hear from me again or see the poor pictures my wife and daughters took, sorry I upset so many people. Believe me I never knew, I try not to upset anyone, sorry again.

mtflight
10-18-12, 06:14 PM
Remember: Suspended silicates in good ol' green coolant have been radically reduced in order to lessen water pump shaft seal wear - most 'green' coolants are now "no silicate" or "low silicate" formula.

This has been addressed before, by a re-named source:


... Simple answer: USE THE COOLANT SUPPLEMENT PELLETS ....

The green silicate coolant has two undesirable side effects that bear mentioning:

One is that the silicates are very abrasive and shorten water pump seal life by abrading the surface of the seal.
Also the silicates can build up on the seal surface and "unseat" the seal causing seepage.
The seal is fine but the silicate contamination does cause a leak. The coolant supplement pellets tend to prevent the latter situation by cleaning the surface of the water pump
seal and preventing the silicate build up. The little fibers in the supplement literally "scrub" the surface preventing the silicate buildup. It doesn't seem to prevent erosion of the seal
by the abrasive silicates unfortunately. The second situation is more pronounced in occasional use cars that might also get a higher than the recommended 50/50 concentration of coolant (more coolant than water). The silicates can "congeal" in low flow areas like the heater core forming this green "jello" that plugs the heater core. The lower the flow, the greater the coolant concentration and the longer the down times the greater the tendency to form the green jello. Usually it can be flushed out with a strong water flow from a garden hose but it is a pain.
Both of these problems prompted the use of DexCool from the factory as well as the long term corrosion protection compared to the green coolant.

And regarding the water pump, I'd rather replace it every 5 years when it leaks than tear the engine down to replace a head gasket and bolts.


...The water pump will be the easiest you've ever changed. It's hard to believe the dealers can somehow justify charging $570.00 to change one. That's about $450.00 profit I'd say. With the special tool it's a snap. Remember that the water pump cartridge is removed by turning it clockwise as viewed from over the left front fender looking into the water pump cavity from the backside after removing the cover. It is installed by turning the special tool counterclockwise - a "left handed thread" install. When the old pump is out remember the o-ring seal that is in a groove in the water crossover casting. Look inside the housing when the water pump is out and you will see it. Put a new o-ring in the groove (should be in the kit with the pump) and make sure it is seated and lubed with antifreeze when installing the new pump.

Check the water pump drive belt and tensioner. The tensioner may need to be exercised and the pivot lubed to keep it moving freely.

----------


Thanks for you're honesty sub you won't hear from me again or see the poor pictures my wife and daughters took, sorry I upset so many people. Believe me I never knew, I try not to upset anyone, sorry again.

Tom I think the pics are just fine, and I commented how nicely your car looks. I hope I'm misunderstanding what you're writing and you won't leave the forum over this. They weren't bothering me at all and I found them a nice distraction. It's not like you post that much, but that's just my $0.02 USD. Edit: if it's not evident, I wasn't one of the ones that allegedly complained.

drewsdeville
10-18-12, 06:26 PM
I dont find a problem with them either. No worse than the ugly, repetitive avatars and signatures used here.

The beauty of an internet board is that you can sift through the pages to your liking, retrieving only the info you are interested in. If you don't like the pictures, skip over them. Effortless, and no drama required.

maeng9981
10-23-12, 03:29 PM
Well, I'm going with studs and regular FelPro gaskets, Dex-Cool and all new seals possible. I took the oil pan apart and I got to see a wonderful scene of gel-like oil deposit everywhere, probably due to severe overheating. I'm surprised this engine even ran, and glad I didn't run it after that overheating episode. After further inspection, the oil leak seems to be from the oil pan, but not the halfcase. I'm resealing the half case anyway.

I am having difficulty removing the main bolts, they act like they are sealed up there good and may break upon removal. I was successful removing none of them. Does it just take quite a torque, or am I doing it wrong?

Also the rear crankshaft oil seal... removal I can do without tools carefully, but the installation tool is over $200 and that's ridiculous for one time use. Is there any alternative, or other tools available for this work?

98eldo32v
10-23-12, 05:53 PM
Main bolts are a huge pain.

You better have a 1/2'" breaker bar with only 6 point sockets and an extension for the breaker bar. The way some of them came loose when I took apart the bottom end on the STS motor, I thought every last one of them snapped when they came loose.

I was lucky and got all of them loose. Better get new bolts for the bottom end.

I didn't take any chances, nor do I think you should either.

----------

Get lucky on ebay for the rear main tool.

Got mine for cheap a while back, practically brand new.

maeng9981
10-24-12, 12:55 AM
Maybe I was too afraid of breaking a bolt. I used my favorite breaker bar and all came right off. It was much like the head bolts coming loose, except lesser torque needed. And yeah, I will get new main bolts. Too much of a horror story to have one break in my block.

Where would be the best source for the main bolts (and rod bolts too)? Dealer?

I snapped some pictures during disassembly that I will post later. The oil sludge is just a pain. More cleaning I guess....

98eldo32v
10-24-12, 01:57 AM
Hit up Chris @ Rippy.

I got new main and rod bolts from him. Eldorado_Red came over to my house to see what he's about to get into. At least teardown and necessary parts.

My advice on rebuilding one of these things, if you THINK it needs replacement do it now and forget it.

Chin up on the oil cleaning. Yes, it a mess and a pain, but when everything is clean things will go a lot smoother.

Hang in there.

Eldorado_RED
10-24-12, 03:30 AM
This guy is the real deal, Its great to have another Cadillac enthusiast in the same area. Take plenty of pics maeng9981. We are going to start on our projects soon.


Hit up Chris @ Rippy.

I got new main and rod bolts from him. Eldorado_Red came over to my house to see what he's about to get into. At least teardown and necessary parts.

My advice on rebuilding one of these things, if you THINK it needs replacement do it now and forget it.

Chin up on the oil cleaning. Yes, it a mess and a pain, but when everything is clean things will go a lot smoother.

Hang in there.

w_b_k
10-25-12, 01:49 AM
It's not the gaskets in and of themselves - it's the bolts, the threads, the open deck, and the siamesed cylinders that don't support the gasket in doing its job.

ding ding ding... we have a winner! :thumbsup:

It really is this combo of things going on here in my opinion as well. If you want to use conventional green coolant because it coats graphite etc... fine. I've got nothing against it. But, if Dex was the cause of failures, why do pre-96 gaskets go too? It's because of what Sub states above. Personally I don't use Dex in my car either, but I don't see it as the cause here. MLS and studs are the way to go... use whatever coolant you want and maintain it accordingly.

Submariner409
10-25-12, 02:33 PM
Someone find and post a picture or three of a pair of stock Northstar head gaskets from an overhaul necessitated by coolant loss - showing clearly where the DEX-COOL has eaten away the gasket between a coolant passage and the cylinder itself. Also include, if possible, the head and block sections showing the leak, and the discoloration on the metal machined surfaces caused by coolant moving through the gasket material.

The coolant does not eat the gasket causing compression leakage; rather, compression leakage begins, coolant loss ensues, overheating occurs and overhaul becomes necessary. Coolant in one or more cylinders after sitting ???? Not because the gasket initially failed: The head lifted and we all know that ethylene glycol coolants can find a microscopic leak.

vincentm
10-25-12, 03:49 PM
Northstar HG chicken vs egg: the new oil war argument lol

Submariner409
10-25-12, 04:30 PM
Northstar HG chicken vs egg: the new oil war argument lol

What's your bosses' side of this question ?

vincentm
10-25-12, 05:54 PM
What's your bosses' side of this question ?

Head bolts

mtflight
10-25-12, 05:59 PM
If the benefit to Dexcool is extended life, then why change it every 2 years?
To be fair, let's compare apples to apples (exclude 2000+ that has different head bolts depth and pitch).
What explains, the significant spike in HG failures from 93-96 vs 97-99? Were the either the head gaskets or head bolts revised? (no to the head bolts)
I have been looking at the most obvious differences and doing a little bit of research along the way.

While generally considered chemically inert, the reaction of carbon with oxygen is one of the simplest reactions. Graphite reacts very slowly with oxygen allowing deep penetration causing a uniform reaction that effects the thermo-physical properties of graphite without changing its geometry. A sheet of graphite is very stable due to its structural bonds (hexagonal, honey-comb), but the edges share a bond with a non-carbon atom/molecule and those are the sites where oxidation occurs. These edges are the places where silicates in conventional green coolant would preferentially bind. powdered graphite is very disordered and is full of these edges that are more likely to react with oxygen. Some free oxygen atoms that bind to the jagged edges may produce CO2 or CO (gas).

I've heard of our type of graphite head gasket be referred as a "cold-rolled graphite" gasket. If they are made with graphite powder (which would have jagged, reactive edges instead of being a structured flat sheet), it would be more prone to damage by oxides. This could be why some gasket manufacturers warn against using graphite gaskets in oxidizing environments. This is where silicates would bind, protecting from further reactions.

An interesting observation is that the market for graphite gaskets grew as the need for finding an asbestos substitute. Some of today's graphite composite gaskets use a binder, NBD (nitrile-butadiene rubber) to keep it all together. Using natural silicone rubber would fail prematurely if in contact with 2-ethylhexanoic acid (we know that now, but we didn't know it in 1993).

CadillacLuke24
10-25-12, 06:25 PM
If the benefit to Dexcool is extended life, then why change it every 2 years?

Old coolant will not protect as well as new coolant. Just like engine oil, ATF, etc.

The spike between [93-96] and [97-99] Headbolt failures can be directly traced, IMHO, to the grade of aluminum used to cast the Northstar engine blocks. In 96 for the 97 model year, based on what I've seen and read, GM went with a cheaper (read: lower quality) grade aluminum when casting blocks to save a few bucks. If there's lower grade aluminum in the engine block, chances are it is less likely to react very well to repeated overheatings, and the difference in heating coefficients allows the headbolts to pull sooner. Basically, where, say, a 95 will overheat a few times but it will be able to survive, a 99 in similar conditions has lower grade aluminum, a looser grip on the head studs, and BOOM "HG failure".

mtflight
10-25-12, 07:09 PM
Old coolant will not protect as well as new coolant. Just like engine oil, ATF, etc.

The spike between [93-96] and [97-99] Headbolt failures can be directly traced, IMHO, to the grade of aluminum used to cast the Northstar engine blocks. In 96 for the 97 model year, based on what I've seen and read, GM went with a cheaper (read: lower quality) grade aluminum when casting blocks to save a few bucks. If there's lower grade aluminum in the engine block, chances are it is less likely to react very well to repeated overheatings, and the difference in heating coefficients allows the headbolts to pull sooner. Basically, where, say, a 95 will overheat a few times but it will be able to survive, a 99 in similar conditions has lower grade aluminum, a looser grip on the head studs, and BOOM "HG failure".

The premise of Organic Acid Technology is that the 2-ethylhexoanate does not deplete like silicates do in conventional green. On paper OAT coolant is as effective on day 1 as it's ever going to be, during the time period stated.

Where have you read about the cheaper grade aluminum being used? I haven't heard that. I know there are inherent flaws in the type of casting used, but I was unaware of any materials changes in this time period. Any information you can find will help.

Submariner409
10-25-12, 07:30 PM
mtflight has also forgotten the Northstar aluminum block metallurgy changes in 96 and 2000. (Does anyone remember the "casting porosity" discussions of the mid-2000's ???)

He's hung up on acid coolant eating the gaskets into foam toilet paper and that's simply not the case.

Again: Show me a Northstar head gasket eaten away by coolant, between a coolant passage and cylinder in the compressed area, to a degree that would allow coolant to flow into a cylinder.

mtflight
10-25-12, 09:32 PM
He's hung up on acid coolant eating the gaskets into foam toilet paper and that's simply not the case.

This is misconstrued.

When did the aluminum metallurgy changes take place, 96? Are there any references to this??

I see that in 1993 the block is a one-piece high pressure 380 Aluminum alloy die-casting with integral iron bore liners. The lower end of the block is two piece. The heads have a "special" 319 Al alloy and are poured in semi-permanent mold technology.

In 2000, I see the same die-cast 380 Aluminum alloy, but I see a "two-piece," 90 degree "V" with cast-in iron sleeves in the specs. The heads have SPM Aluminum 319 alloy as well. The lower crankcase is Aluminum alloy 383.

CadillacLuke24
10-26-12, 02:34 AM
I don't have the information specifically, but I've read that they changed the metallurgy (like Sub said), and it was not as good as a grade of aluminum. More porous I think. If I do find stuff, I'll post it.

automark
10-26-12, 03:35 PM
Thank you all for these incredible details! Please continue to discuss, and especially do find the details on the AL metalurgy changes in 96 and 2000. I am very interested.
Thanks again for this specific information.
Best regards,
MSH