: What Materials Are Used In Norhtstars ?



Cadillacboy
03-21-07, 06:18 PM
I would like to hear what you guys think of this idea. I was reading some reviews and found that :
"maybe either an all aluminum engine or an all cast iron engine. The 4.6L has a cast iron block and an aluminum head, both materials have different expansion rates paving the way for blown gaskets or cracked heads. I tip my hat to Caddy for the post-2004"

Is this right ? I knew that Northstar is all aluminum :confused: .I am confused a bit here .However what's even more confusing to me is that those GM Engineers don't have an idea of what an engine should be made of , combined and put together ? Just because reliability problems are addressed from using different materials .
For my thoughts I would be happy if Northstars have cast iron blocks just like Vortec engine .

eldorado1
03-21-07, 06:22 PM
The 4.6L northstar is all aluminum.

The 4.9L has an iron block with aluminum heads.

The reason the 4.6L northstar blows headgaskets is because the aluminum threads in the block pull out (causing the head to be held on by fewer and fewer bolts) and/or the gasket rusts out due to improper maintenance of the cooling system.

1997BlackETC
03-21-07, 06:36 PM
I just thought of a preventative maintenance idea that would prevent head gaskets from blowing on the northstars. Run a heliarc weld around the head and the block, this would keep the head from ever lifting from the block. If by some freak thing the head gasket ever did go then, just replace the engine with a rebuilt one for $3295.00. I guess they my not be too happy with the core that was turned in, but, oh well, thats life.

Cadillacboy
03-21-07, 06:38 PM
Thanks for your input . I see why Northstar gets headgasket failures quite often .If it were a cast iron thouse threads wouldn't pull out

dratts
03-21-07, 06:38 PM
Eldorado, I have a ton of respect for you due to the success you've had with your N* projects and the trans controller you built, but I think you have it backwards. Doesn't the 4.9 have an aluminum block and iron heads? I know that this is just the opposite of most iron/aluminum combos. I would be interested in the 4.9 if trick flow or someone made some good heads for them.

eldorado1
03-21-07, 06:44 PM
Doesn't the 4.9 have an aluminum block and iron heads?

I think you might be right :)

1997BlackETC
03-21-07, 07:05 PM
Eldorado, I have a ton of respect for you due to the success you've had with your N* projects and the trans controller you built, but I think you have it backwards. Doesn't the 4.9 have an aluminum block and iron heads? I know that this is just the opposite of most iron/aluminum combos. I would be interested in the 4.9 if trick flow or someone made some good heads for them.

Yes, thats right, Aluminum block and Cast Iron heads. Your probabley not going to see any aftermarket makers making special head for this motor as its just not a popular hot rod motor like the Rat and Mouse chevy motors.

dkozloski
03-21-07, 07:40 PM
I just thought of a preventative maintenance idea that would prevent head gaskets from blowing on the northstars. Run a heliarc weld around the head and the block, this would keep the head from ever lifting from the block. If by some freak thing the head gasket ever did go then, just replace the engine with a rebuilt one for $3295.00. I guess they my not be too happy with the core that was turned in, but, oh well, thats life.
The first step in implementing that idea is to preheat the whole assembly to 500deg.F. That's the end of the gasket and any other sealer anywhere in the engine. That's got to be one of the most rediculous goddam schemes I've ever heard. You're not related to Al Gore are you?

dkozloski
03-21-07, 08:07 PM
On a more serious note there are many examples of engines that have the heads cast with the cylinders or cylinder block and everything loads from the bottom. The Meyers and Drake Offenhauser, the Allison V1710, some Rolls-Royce Merlin versions, the Crosley Hot Shot are all enbolc with no head to crankcase joint.

Ranger
03-21-07, 08:26 PM
You're not related to Al Gore are you?:histeric: :rofl:

ewill3rd
03-21-07, 08:29 PM
The N* engine is Aluminum with cast in grey iron sleeves.
The 4.9 has an aluminum block with iron cylinder inserts. Those are pretty cool in that you can replace one whole cylinder without having to rework the block. I was quite surprised at the first one I took apart.

I rarely see a N* pull head bolts that didn't overheat due to inattention or lack of maintenance FIRST.

Welding around the head is just a crazy idea, plus it wouldn't work anyway. The real pressure is nearest the cylinder where the bolts are, it could easily blow the head gasket completely loose in the center even if it was welded around the edges, not to mention the dozens of other problems that would create. I hope that was just a joke.
Actually one of the best ways to hold a head on is by using studs insted of bolts, but it costs more and it can be more complicated... but that is another topic.

The N* block and heads are all aluminum. There are lots of vehicles out there with cast blocks and aluminum heads that have little or no problem with sealing or thermal expansion variation.
Don't believe everything you read.
(except of course what I tell you :D)

Ranger
03-21-07, 09:36 PM
Actually one of the best ways to hold a head on is by using studs insted of bolts, but it costs more and it can be more complicated... but that is another topic.
That battle has been fought before. There was a very lengthy and "heated" :gun2: :brutal: discussion between someone and our old Guru about this before. Since it involved the Guru, I doubt that it can be found with a search.

CadillacSTS42005
03-21-07, 09:59 PM
dang...

eldorado1
03-21-07, 10:21 PM
That battle has been fought before. There was a very lengthy and "heated" :gun2: :brutal: discussion between someone and our old Guru about this before. Since it involved the Guru, I doubt that it can be found with a search.

The end result of which was that studs do NOTHING to help the situation specific to the northstar, because the weak link will always be the block threads.

dkozloski
03-21-07, 10:34 PM
Studs are also a big production problem. Sliding head gaskets down over studs is hard to do with automatic equipment. According to Bbob, the Cadillac Northstar heads, block, head gasket and capscrews were an interlocking engineered system. A big bone of contention was always what came first, the pulled threads or corrosion. I've always suspected the metalurgical properties of the die cast block. Uneven cooling is the bugaboo of die castings and the resulting nonhomogenous grain structure causes failed threads in my scenario.

JimD
03-21-07, 11:07 PM
I saved many of the Guru's lectures on the reasoning behind why the Northstar is the way it is. Below is part of a discussion that touched on a number of issues (as usual). It appears that "failed bolt hole threads" can result from a gasket failing in such a way that exposes the bolt-to-block junction to coolant.

And as soon as the bolt hole's integrity is compromised, it all goes downhill from that point.

The following is not my words:

================================================== =====

There is always an issue of galvanic corrosion happening
when you have steel against aluminum. That has been
recognized for several decades...yes...LOL. That is why,
for instance, the Northstar headbolts have a special
coating on them, have the micro-encapsulated loctite
compound on the threads to lubricate/lock/seal the
threads and was the driving force behind putting each of
the Northstar head bolts into it's own, dry, sealed
chamber to keep any comtaminates or electrolytes away
from the aluminum/steel interface.

1997BlackETC
03-22-07, 12:33 AM
Yes, I was just joking. Just as I was joking about the spark plug thread causing the headlights to be brighter using more efficient spark plugs, lol. Had a lot of people really going with that one though :).

Mountie
03-22-07, 01:05 AM
Sounds like a job for Mythbusters.........

Or..... instead of welding the heads to the block,

...while the engine is out of the car ( I assume you will remove the engine to do the welding)......:alchi:

Dissasemble the entire Northstar down to the bare block / heads, what is keeping you from installing time serts then return the engine to the empty space it belongs, put the correct coolant formula into the system, then CHECK YOUR COOLANT LEVEL!~!!!!!!:rant2:

ewill3rd
03-22-07, 05:31 AM
Well I wouldn't want to engage in a big debate over studs v bolts, I just mentioned it because I can see some advantages to doing it that way.
Yes studs make assembly harder and yes, the aluminum block threads are probably the weakest link in the N* "chain", so to speak.

Glad you were joking about the welding ;)

codewize
03-22-07, 10:22 AM
It's the design of the threads themselves. The pitch, angle and depth I imagine. There are a million aluminum engines out there so it's not the fact that it's aluminum.


Thanks for your input . I see why Northstar gets headgasket failures quite often .If it were a cast iron thouse threads wouldn't pull out


Are you sure you were joking? You did fight that for days until we threw all of our electrical engineering knowledge at you forcing you to give up the debate.

Yes, I was just joking. Just as I was joking about the spark plug thread causing the headlights to be brighter using more efficient spark plugs, lol. Had a lot of people really going with that one though .

dkozloski
03-22-07, 10:51 AM
The N* engine is Aluminum with cast in grey iron sleeves.
The 4.9 has an aluminum block with iron cylinder inserts. Those are pretty cool in that you can replace one whole cylinder without having to rework the block. I was quite surprised at the first one I took apart.

I rarely see a N* pull head bolts that didn't overheat due to inattention or lack of maintenance FIRST.

Welding around the head is just a crazy idea, plus it wouldn't work anyway. The real pressure is nearest the cylinder where the bolts are, it could easily blow the head gasket completely loose in the center even if it was welded around the edges, not to mention the dozens of other problems that would create. I hope that was just a joke.
Actually one of the best ways to hold a head on is by using studs insted of bolts, but it costs more and it can be more complicated... but that is another topic.

The N* block and heads are all aluminum. There are lots of vehicles out there with cast blocks and aluminum heads that have little or no problem with sealing or thermal expansion variation.
Don't believe everything you read.
(except of course what I tell you :D)
I believe the sleeves are cast in place and not meant to be replaced like sleeves in a diesel. That being said they can be bored out and a new custom sleeve pressed in just like a cast iron block can be repaired.

Ranger
03-22-07, 11:14 AM
Koz,
I think Ewill was talking about the 4.9. Those sleeves are replaceable. The Northstars are cast in place.

dkozloski
03-22-07, 11:49 AM
Koz,
I think Ewill was talking about the 4.9. Those sleeves are replaceable. The Northstars are cast in place.
Ah! So! Thanks.

AlBundy
03-22-07, 12:36 PM
That battle has been fought before. There was a very lengthy and "heated" :gun2: :brutal: discussion between someone and our old Guru about this before. Since it involved the Guru, I doubt that it can be found with a search.

That thread was posted here about a week or two ago. The high oil consumption, pull headbolt thread by Bluemoon. Bluemoon & gtm2u vs Beelzebob.

ewill3rd
03-22-07, 12:58 PM
Thanks for clearing that up Ranger, yes I was talking about the 4.9.
The N* liners are indeed cast in place.

Submariner409
03-23-07, 08:33 PM
:) Hey, Koz.......How many people would believe that a series of Crosley OHC 4 engines were made up of a bunch of steel stampings jigged together, copper/bronze tape in all seams, and cooked in an induction oven to bond them together? Soon as the coolant went in, instant battery........we used to run 'em in hydroplanes, up to 10k rpm.....valve work was a bitch......Buddy of mine has a mint Rolls Royce Merlin V12 in his garage. All black, gold, and chrome, but I THINK this one was a tank engine.

dkozloski
03-23-07, 11:22 PM
:) Hey, Koz.......How many people would believe that a series of Crosley OHC 4 engines were made up of a bunch of steel stampings jigged together, copper/bronze tape in all seams, and cooked in an induction oven to bond them together? Soon as the coolant went in, instant battery........we used to run 'em in hydroplanes, up to 10k rpm.....valve work was a bitch......Buddy of mine has a mint Rolls Royce Merlin V12 in his garage. All black, gold, and chrome, but I THINK this one was a tank engine.
Lloyd Taylor was the inventor of the fabricated motor for Crosley. There were thousands made during WWII for pumps and such. It was redone in cast iron but was still an enbolc design. The last application I remember of the basic engine was the Fisher Pierce Bearcat 4-stroke outboard. I used to rebore them for the local outboard shops because nobody else knew how to deal with the closed end cylinder. They were about 55 horsepower I think.

jadcock
03-26-07, 12:48 PM
ewill3rd, do you guys in the service world see a reduction in head gasket problems with either:

A) The change to Dex-Cool in 1996, or
B) The slight change in head bolt design in 2000?

It would be interesting to know if you see a lot more 93-95 engines, with the green coolant, or a lot more 93-99 engines, due to the original design head bolts. I'm sure that by definition you see more older than newer engines...just the nature of the beast. I'm just wondering if you think you can pinpoint any breakpoints in the occurances?

ewill3rd
03-26-07, 04:31 PM
I can't really answer that for two reasons.
First of all, I don't ever do them.
We do a lot of them in our shop though. We have a heavy duty department that handles all that sort of work.

Secondly, there are simply more of them on the road with dex cool.
Dex has been in use since the '96 production year, that makes 11 years worth of cars on the road. Pre '96 you had what... 3 years?
We don't even see that many cars pre '96. Most of the stuff that is that far out of warranty is serviced in the aftermarket.
I wish I could speak to those points for you but I just don't deal with it enough personally to be able to give you a good answer.

clarkz71
03-26-07, 05:16 PM
I havn't seen a 93-95 headgasket on this forum in awile. Lots of 96 and up though.