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Northstar Engines and System Technical Discussion Discussion, Thoughts on Dex-Cool and Head Gaskets in Cadillac Engine Technical Discussion; So sub, where did that gasket fail? You're saying the gasket was fine, it was the bolt that failed? I'm ...
  1. #61
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    Re: Thoughts on Dex-Cool and Head Gaskets

    So sub, where did that gasket fail? You're saying the gasket was fine, it was the bolt that failed? I'm not sure I could determine that by looking at it. Once the coolant gets between the sandwich-- does that make a difference? If its the bolts then no amount of maintenance could prevent it right?

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Yep, bolts. We would need to see the entire gasket, close up, both sides. Coolant got past those fire rings somewhere...............for some reason, and if the fire rings are not blown out/open, then coolant went around them from loss of clamping pressure - those fire rings clamp around the entire circumference of the cylinder on both sides of the gasket - coolant did NOT run "through" the gasket material into a cylinder.

    What we're seeing there is the uncompressed gasket material hanging down into the open deck coolant passage. We're looking up at the "bottom of the gasket - from down in the block. The gasket material between the fire ring and open deck/liner curves appears clean, shiny and compressed. (But, that said, I don't like the small amount of gasket/space between the siamesed cylinder liners.)

    Remember about 3 years ago when AJ posted the pictures of a 1999 cylinder block with nasty thread damage and porosity in the bolt holes ?? Those pics might still be down in Northstar Performance, sticky, "Root cause............."

    EDIT: Those gaskets are made no differently than OEM or rebuild gaskets for most engines on earth. The gaskets pictured do not evidence any coolant "in the sandwich", and the flat, shiny areas are typical of any graphite/felt/metallic composition head gasket after long, hot use.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Quote Originally Posted by mtflight View Post
    So sub, where did that gasket fail? You're saying the gasket was fine, it was the bolt that failed? I'm not sure I could determine that by looking at it. Once the coolant gets between the sandwich-- does that make a difference? If its the bolts then no amount of maintenance could prevent it right?
    Keep the engine from overheating grossly and frequently and you'll be good to go.

    The big thing with the Northstars, and why longer bolts with coarser threads, even Jake's SureGrip studs, is that it seems the bolts pull out of the block first. The chicken or the egg debate, just like Ranger said. And like Sub said, it has to get past the gasket into the cylinder. Bolts that have lost their clamping power allow for that quite easily.

    The ingredient deteriorates silicone and rubber. Okay, gotcha. Yeah, I don't know how much of that stuff is in Northstar headgaskets, or in my Dad's Vortec, or in any engine, for that matter. I also don't know how much of the gasket is in contact with the coolant. My question is, if 2-EHA is degrades sillicone rubber in such a manner, why is the relative increase in HG failure seen ONLY in the Northstar V8? There certainly is the possibility that other HGs in different cars are designed differently, yes, but HGs have a high "failure" rate in ONE type of engine, I highly doubt gasket makers are going to redesign their product line. Again, I could be wrong, but common sense dictates the aforementioned.

    Basically, if there were a problem with the presence of 2-EHA in coolant, countless late model vehicles would have HG issues, and the coolant would have been redesigned a very long time ago.

    You have very valid points. It makes sense that an ingredient in coolant, which can degrade components possibly found in HGs, can cause HG failure. I agree with you there. If there's enough silicone rubber in the HGs, then BINGO we found the problem.

    The point being made here is that evidence rather strongly suggests regular maintenance eliminates the potential for problems. Yes, referrencing the article you posted, coolant appeared to eat gaskets. Intake gaskets made of rubber. Looking at the article, I would say it's rather probable that coolant eating the rubber caused that mess, and I digress upon earlier statements about Bar's Leak. I still think that stuff is worthless, but looking at some of the pictures suggests a different problem at hand. Late 90s 5.7 V8s were NOTORIOUS for IMG failure. My Dad, previous to his ESV, had a 97 Chevy Suburban. Guess what happened at about 50K miles, before he traded it in?

    If the chemical deterioration of the rubber component of the HGs was noticeable, would it not have happened in the HGs of the 5.7 V8s as well? This is just my opinion, but if there was a problem with the coolant deteriorating the HGs, they would have quite clearly and obviously failed in the 5.7 V8s that suffered the IMG failures.

    With the Northstar, the coolant may very well deteriorate the gasket. The thing is, in my opinion, Northstar V8s do NOT experience a HG failure, speaking very strictly.

    Northstar V8s suffer a cylinder head bolt failure. The Head bolts are Steel. The headbolts are aluminum. This is on a transverse, FWD layout, high performance V8 engine. When the coolant system fails in one way or another, the engine heats up VERY quickly due to its orientation in the engine bay-especially the rear bank of cylinders (closest to the firewall). In a RWD, longitudnal V8 setup, both banks get equal cooling due to equal airflow over both banks. In the transverse setup, the front gets cooling immediately. The rear bank likely gets equal cooling, but this is after the fans kick in and circulate air to the rear bank. Additionally, the rear bank still has to deal with heat flow from the front bank. Not an ideal setup when things get hot. And when the engine overheats, the steel and aluminum heat, but at differing rates. Aluminum is less dense than steel, so it heats quicker. What happens is that the aluminum surrounding the steel bolt expands quickly, leaving the steel bolt "hanging" in space, so to speak. Even with an insignificant gap between the two, the headbolts can pull out because the force of the internal combustion acts like a big ginourmous hammer. If you briefly overheat the car, realize the issue, and stop the engine, that removes the force of combustion, which likely would almost eliminate movement of the headbolts. Again, just my opinion, but that's what makes sense to me. Where the headbolts fail is that most individuals who drive Northstar V8 powered cars aren't thinking along this train of thought. Most people likely don't know how severe the consequences of overheating a Northstar really are. They just know that if they drive up hills or for a long time the car overheats. When the overheating is repeated, and the duration of overheating is long, this is where you run into your problems. This is when the headbolts lose clamping force, begin to pull away from the block, and allow the coolant through to the cylinder head. And I would venture to guess that is where the gasket deterioration comes from. You are likely right, I bet it happens, but I think that gasket deterioration is a by-product, not a cause.

    Why I think regular maintenance of the coolant, and coolant system in general, is so important is that it allows you to catch problems before they ever happen. Low on coolant? If you are checking regularly, you will know before the car overheats. Checking frequently may help discover leaks or other weaknesses in the cooling system. Coolant also-just like engine oil and ATF-wears out over time. Old coolant can't protect your engine from extremes as well, or manage heat as well. This allows overheating to happen more readily. Change it out and you minimize-maybe even eliminate-that risk. If coolant eats away at silicone rubber in gaskets, perhaps this happens as coolant ages. Changing it out eliminates the risk.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Very informative post, Luke. I suppose I don't know of my 98 overheated on the previous owner. It didnt overheat on me but I can see how the overheating can cause a lot of damage. It began failing after pushing it. The temperature was 240 or so after passing and wasn't coming down. It was spewing coolant out the overflow and I dumped it weeks later after a new radiator cap etc. it would over pressurize the coolant and push it out. I was heartbroken but got my 03 afterward.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Quote Originally Posted by Submariner409 View Post
    Yep, bolts. We would need to see the entire gasket, close up, both sides. Coolant got past those fire rings somewhere...............for some reason, and if the fire rings are not blown out/open, then coolant went around them from loss of clamping pressure - those fire rings clamp around the entire circumference of the cylinder on both sides of the gasket - coolant did NOT run "through" the gasket material into a cylinder.

    What we're seeing there is the uncompressed gasket material hanging down into the open deck coolant passage. We're looking up at the "bottom of the gasket - from down in the block. The gasket material between the fire ring and open deck/liner curves appears clean, shiny and compressed. (But, that said, I don't like the small amount of gasket/space between the siamesed cylinder liners.)

    Remember about 3 years ago when AJ posted the pictures of a 1999 cylinder block with nasty thread damage and porosity in the bolt holes ?? Those pics might still be down in Northstar Performance, sticky, "Root cause............."

    EDIT: Those gaskets are made no differently than OEM or rebuild gaskets for most engines on earth. The gaskets pictured do not evidence any coolant "in the sandwich", and the flat, shiny areas are typical of any graphite/felt/metallic composition head gasket after long, hot use.
    I remember AJ's post as far as poor casting.

    But not all blocks have the symptom and some engine's bolts are so tight they snap loose when taking them off. I suppose some could be hg some could be bolts. Still seems mysterious. Btw what happened to the OP That took the pictures above. seems the post ended on page 18 before the engine was put back together.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Thanks MT. It is weird that some go with the bolts apparently still intact, which suggests that coolant can deteriorate the gaskets. Good on ya for trying to figure it out so you don't have to go through it again!

    Glad things worked out for you in the end. Still have the 03, or is it the 99 as listed? How's she holding up thus far?

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Sub brings up a good point that I hadn't considered. Back to square one with the chicken and the egg. I'm just gonna change the coolant (Dex) every two years and pray to the Northstar Gods.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    And if the HGs fail I know Jake's phone number.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Joe is just down the road from me (should the need ever arise).

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    Quote Originally Posted by CadillacLuke24
    Thanks MT. It is weird that some go with the bolts apparently still intact, which suggests that coolant can deteriorate the gaskets. Good on ya for trying to figure it out so you don't have to go through it again!

    Glad things worked out for you in the end. Still have the 03, or is it the 99 as listed? How's she holding up thus far?
    03 gone. Low speed front end collision totaled it, but the lady in front of me saved a squirrel.
    99 running great--conventional green coolant. I opened the radiator drain and pushed 5 gallons of distilled water through until it came out clear-ish. Then I added the bars leak powder to the upper radiator hose. Refilled half the coolant capacity with conventional green silicate coolant, purged the system of air, and topped off with distilled water as needed. Level is good and steady 1.5" from the neck into reservoir. 95K miles. Fingers crossed.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Quote Originally Posted by mtflight View Post
    03 gone. Low speed front end collision totaled it, but the lady in front of me saved a squirrel.
    99 running great--conventional green coolant. I opened the radiator drain and pushed 5 gallons of distilled water through until it came out clear-ish. Then I added the bars leak powder to the upper radiator hose. Refilled half the coolant capacity with conventional green silicate coolant, purged the system of air, and topped off with distilled water as needed. Level is good and steady 1.5" from the neck into reservoir. 95K miles. Fingers crossed.
    I hope she's happy. IMHO, a Cadillac is FAR more valuable than a stupid rodent.

    Glad the 99 is running great so far. Hopefully it keeps up!

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Bummer. "The lady in front of" you would be happy to know that I shoot and eat the damn gray fuzzy-tail rats.

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