THE HEADGASKETS BARELY SURVIVE HALF THAT MILEAGE........
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.
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.
Pete and RePete were on a fence. Pete got knocked off with a baseball bat.
WHO WAS LEFT?
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.
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?
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.
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.
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.
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.
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.
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?
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.
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....
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.