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Northstar Engines and System Technical Discussion Discussion, Thoughts on Dex-Cool and Head Gaskets in Cadillac Engine Technical Discussion; I want to throw my .02 worth in here. GM started using dexcool in the mid 90's because more and ...
  1. #46
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    Re: Thoughts on Dex-Cool and Head Gaskets

    I want to throw my .02 worth in here. GM started using dexcool in the mid 90's because more and more of the engines were using aluminum and iron motors. Green antifreeze seems to corrode aluminum, especially some of the early aluminum engine parts because of the alloys that were used. I can't count how many motors I've taken apart that had iron block and aluminum heads with green antifreeze. Every single one of them had corrosion in the heads where the coolant passages are...some of the passages were actually completely coroded up and had to be dug out. I never really considered the anti freeze as a culprit until I started working primarily on the lt1/lt4 and lsx motors. This is when I started using all dexcool. I have converted all of my motors to dexcool, and have had no problems with head gaskets or corrosion. I will add that when people convert to dexcool they seem to think that they can wait 100k before the dexcool needs changed. I don't care what the lable says if you don't maintain your Northstar coolant system, it doesn't matter what you run in it. Your going to have problems with head gaskets corroding. Dexcool is acidic, but that is why it works well in aluminum motors. It etches the metal keeping it from or slowing corrosion. I'm not 100% sure but somewhere i heard that green antifreeze is more of a base and tends to corrode certain alloys. Look at what salt water does to steel. BTW-I'm no engineer, but I'll be sticking with dexcool.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Where is Jake at Northstar performance at? Ranger and Sub you can argue against the Dex-cool theory all day long, but I am going to listen to the man who has pulled at least a 100 of the heads off the northstars and that would be Jake. He said himself in another thread that the head gaskets are in much worse shape on the engines with Dex-Cool.

    In reality it is probably a combination of both the head bolts and the Dex-Cool.

    Ranger your example with your Bonneville not blowing head gaskets is moot seeing as I blew the head gaskets on my Bonneville with 170k on it.

    Lets put all this arguing to an end and setup an experiment. I say someone go buy two sets of head gaskets from a northstar(4 gaskets). Put gasket 1 in fresh dex-cool, gasket 2 in fresh green, gasket 3 in a few year old used dex-cool out of an engine, and a few year old green out of an engine. Let them sit for however long it takes to see damage and put this argument to rest.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Just a quick update to this 2009 thread. It turns out that Potassium 2-ethylhexanoate (and possibly Sodium 2-ethylhexanoate in other organic acid technology coolants) are detrimental to silicone rubber and to nylon 6,6. This is a fact, as far as I know. Some gaskets had these affected materials in higher quantities than others, thus it was easy to match cause and effect in some applications, for example the Dex-Cool lawsuit covering dozens of GM platforms, which was won by the plaintiffs. Yet in other platforms, like the Cadillac Northstar, it is difficult to show because the blown headgasket happens many years later, if at all.

    The big question is, how much silicone rubber and/or nylon 6,6 is in the OEM headgasket? As pointed out there most certainly is an increase in head gasket failure starting in 96 with the change to dex-cool.

    So the important thing will be, if you have a failure, make sure to get a headgasket that does not include nylon 6,6 or silicone rubber if you plan to continue using Dex-Cool or any other OAT coolant.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    As far as I know headgaskets are either steel or graphite. NEITHER of which include rubber or nylon.

    Gee, since Dex is so sinister and evil, I wonder why my Dad's Escalade (03 ESV) is soldiering on with likely the original coolant, and it's a reliable as the sunrise?

    Change your damn coolant every 3 three years max and forget about what brand to buy. JUST like the oil wars.

    That was a little bit entertaining, not gonna lie

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Quote Originally Posted by CadillacLuke24 View Post
    As far as I know headgaskets are either steel or graphite. NEITHER of which include rubber or nylon.

    Gee, since Dex is so sinister and evil, I wonder why my Dad's Escalade (03 ESV) is soldiering on with likely the original coolant, and it's a reliable as the sunrise?

    Change your damn coolant every 3 three years max and forget about what brand to buy. JUST like the oil wars.

    That was a little bit entertaining, not gonna lie

    See this article.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    That's the intake gaskets. The general discussion here is on HEAD gaskets. Two completely different things.

    One argument against that guy is that he added Bar's Leak. GM even stopped using additives of such nature.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Btw dexcool isn't sinister or evil. Those are your words.

    The issue is really chemistry. Not good vs evil. silicone rubber and nylon 6,6 vs 2-EHA. Today's cars don't have those issues because materials have been adapted. Are you saying Bars Leak is bad?

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Quote Originally Posted by mtflight View Post
    Btw dexcool isn't sinister or evil. Those are your words.

    The issue is really chemistry. Not good vs evil. silicone rubber and nylon 6,6 vs 2-EHA. Today's cars don't have those issues because materials have been adapted. Are you saying Bars Leak is bad?
    Sarcasm dude. Did you read the whole sentence?

    My point is that Dex-Cool is viewed as "evil" or "bad when nothing could be further from the truth. The problem is that people think they never have to change it, when that is just not the case. If you got a 99 DeVille new and changed the coolant every 2 years, and made sure it never overheated, I'd highly doubt the headgaskets would ever be an issue. Case in point, there's a dude in the Northstar tech forum with 540,000 miles on his 98 DeVille, and the engine hasn't been altered from the original factory set up. His secret? Regular maintenance. It's all about maintenance.

    IMHO, Bar's Leak is worthless. Snake oil at its finest. GM USED to put coolant seal tabs in cars from the factory. They quit because the only thing said tabs did was clog up passages. Bar's Leak is sold along the same lines of those sealant tabs, so yes I'd say its bad.

    The issue is chemistry, I agree there. Chemistry in the differing properties of aluminum and steel, and also physics in how they expand differently.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Well the epidemiological head gasket poll on the site doesn't support what you're saying, and the failed Northstar head gaskets crumble on alleged well maintained cooling systems.

    The ground up ginger root and walnut shell fibers in the Bars Leak clean silicates off the water pump impeller surfaces ( in the years before dexcool.) They were also prescribed to prevent or correct nuisance leaks, as they expand when exposed to dry air--plugging up leaks. Two of my Northstars came with the sticker advising their use of the tabs. They work and if used properly they don't cause issues. I have used them since 2005.

    2-EHA disintegrating nylon and silicone rubber has nothing to do with cooling system maintenance. You missed the point. You also give good advice to maintain cooling system but it masks the point of the post.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    My 2002.5 has the GM radiator cover sticker that says to use the approved tablets in the cooling system. Well and good. The car was built in 02/02, bought in 06/02, first coolant exchange in 06/05, I bought it in 11/05, did coolant changes in 11/07, 12/09 and 12/11. In NONE of those coolant changes was the GM tablet used - I have the original owner's voice say-so and I didn't use them, either. The engine loses not one drop of coolant in the 2 years between coolant changes. 2 year coolant changes ??? - - - Yep, I've been in the car building/rebuilding/overhaul business (privately and commercially) off and on for 57.5 years and have seen, first hand, what neglected coolant can do to an engine. You wanna get really anal over coolant condition ??? - OK - Every 3 months, during normal underhood checks, I siphon off 2 quarts of coolant and replace it with the same amount of new 50/50 Prestone DEX-COOL. What comes out of that coolant reservoir is crystalline clear orange fluid - every time. The car is not babied - ever - and every time I get the chance I run the dog snot out of it. It hasn't let me down yet, and I seriously doubt that it will.

    My car, my case, my 2¢ .

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    Re: Thoughts on Dex-Cool and Head Gaskets

    I've changed the coolant on my 99 twice this year: once as preventive maintenance, another time during the water pump replacement. I changed it about 3-4 times on my 98 before the HG went (maintenance, then radiator twice).

    The coolant pellets were no longer factory as of 2003. My DHS smelled like coolant around the intake area. I put the pellets in and it stopped leaking. I don't think the pellets will harm anything.

    I'm merely trying to get as much information as possible to understand the issue, and to share this information for anyone that would like to chime in with their own experiences. This is what has happened countless times





    http://www.cadillacforums.com/forums...ml#post2911126 OP

    The gasket material flakes off in the area over the water jacket. it's not always corrosion from neglect. The OP mentions the steel looks fine. So what makes the gasket crumble? Does it look like chemical break-down to you?

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Could be chemical break down, but not necessarily from the coolant. Yes, it's certainly possible, but you've got exhaust gasses in there too. Go find a car with bad HGs, determine what the chemical composition is, and you'll know.

    I don't know what causes them to fail. The point of my posts is that changing your coolant frequently is chaep insurance against HG failure. It will not completely eliminate the problem, but it will go a long ways in clearing it up. You say the cars with HG failures on the poll are ALLEGEDLY well maintained. They certaily could be, but many are used cars that may not have a complete service record for the current owner to reference.

    Dex-Cool could eat head gaskets, but I highly doubt it. The whole fiasco during the late 90s was over INTAKE gaskets, not HEAD gaskets. Two completely different parts. Dex eating intake gaskets, I can believe. Dex eating head gaskets seems more far fetched. Like I mentioned in an earlier post, if Dex ate head gaskets, my Dad's 2003 Escalade ESV, filled from the factory with Dex, should NOT be as reliable as it is. I'm not sure, but knowing my Dad, chances are the factory Dex is in his cooling system. It doesn't overheat, act up, none of that. Again, if Dex is so bad, his SUV should have broken down long ago.

    Dex may act differently in a Northstar with bad headgaskets. The thing is, if Dex breaks down so quickly and is so harsh on cooling components, you'd see hundreds of thousands of other GM vehicles with HG problems. In my humble opinion the engine is repeatedly overheated, weakening and eventually eliminating the steel bolts' grip on the aluminum head. Many sources suggest GM used inferior casting techniques, which adds to this idea.

    You may be onto something. The thing is, the vast majority of trends say you might not be.

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Quote Originally Posted by CadillacLuke24 View Post
    Could be chemical break down, but not necessarily from the coolant. The point of my posts is that changing your coolant frequently is chaep insurance against HG failure. It will not completely eliminate the problem, but it will go a long ways in clearing it up. You say the cars with HG failures on the poll are ALLEGEDLY well maintained.
    Dex-Cool could eat head gaskets, but I highly doubt it. The whole fiasco during the late 90s was over INTAKE gaskets, not HEAD gaskets. Two completely different parts. Dex eating intake gaskets, I can believe. Dex eating head gaskets seems more far fetched. Like I mentioned in an earlier post, if Dex ate head gaskets, my Dad's 2003 Escalade ESV, filled from the factory with Dex, should NOT be as reliable as it is. I'm not sure, but knowing my Dad, chances are the factory Dex is in his cooling system. It doesn't overheat, act up, none of that. Again, if Dex is so bad, his SUV should have broken down long ago.

    Dex may act differently in a Northstar with bad headgaskets. The thing is, if Dex breaks down so quickly and is so harsh on cooling components, you'd see hundreds of thousands of other GM vehicles with HG problems. In my humble opinion the engine is repeatedly overheated, weakening and eventually eliminating the steel bolts' grip on the aluminum head. Many sources suggest GM used inferior casting techniques, which adds to this idea.

    You may be onto something. The thing is, the vast majority of trends say you might not be.
    There are so many things on your post that you attribute to me, I don't even know where to begin. I'm not attempting to explain everything. I just shared some information which is factual.

    I wouldn't say that all cars with HG failures on the site poll are well maintained because I don't know that to be a fact. I did say some of the cars that have failed head gaskets had been well maintained. I'm sure you've read about some of these as well.

    The Northstar failed head gasket poll is a form of "epidemiological" study, it doesn't prove anything. It may hold some clues and there's a sharp spike in 97-99.

    What I did share is that 2-EHA, which is in a majority of modern organic acid technology coolants (including Dex-Cool in the form of potassium 2-ethylhexanoate), degrades nylon 6,6 and with silicone rubber. Obviously it is a non-issue if contact with those materials are avoided.

    Do some head gaskets have silicone rubber? yes it is heat resistant and chemical resistant. For example, some Ford and Chrysler engines have "rubber coated embossed" (RCE) head gaskets. Silicone rubber is a common material with desirable qualities (as is nylon 6,6... there's even a rifle made by Remington called the Remington 66).

    Do you know what percentage of silicone rubber is in the OEM Northstar head gasket? I didn't think so. Neither do I. How about how much of it in the Chevy engine in the ESV? Do you know what area of the gasket is in contact with the coolant?

    Are there other variables involved, yes. For instance how much silicone rubber is in the head gasket? If none, then 2-EHA becomes a moot point. I'm sure we can agree on that. One other factor is how much of the silicone rubber is in direct contact with 2-EHA? On the Northstar, the water jacket has an open deck design thus a larger area of coolant is in direct contact with the gasket. Does this play a role? of course it would (again, assuming there's silicone rubber or nylon 6,6 in its composition).

    I didn't say that "dex breaks down so quickly and is so harsh on cooling components," your quote.

    You said "The point of my posts is that changing your coolant frequently is chaep insurance against HG failure. It will not completely eliminate the problem, but it will go a long ways in clearing it up. "

    But where's the logic to that if the head gasket indeed had silicone rubber as a sealant or binder? In that case refreshing the 2-EHA frequently wouldn't make much sense, would it?

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Those pics sure do appear to be deteriorated gaskets where they came in contact with the coolant. So now we have a new chicken and egg question. Did the coolant "CAUSE" the deterioration or was the gasket inferior and would have deteriorated with any coolant? I have asked the same question that Luke has many times. Why only on the Northstar? I am sure that whoever produces HGs for the Northstar also produces them for other GM engines AND GM uses Dex in all their engines. In the words of Kelly Bundy, "It makes the mind wobble".

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    Re: Thoughts on Dex-Cool and Head Gaskets

    Yes, the uncompressed head gasket material in those pictures is perforated - but it's of NO consequence because it's perforated into the coolant jacket open deck area, not through the cylinder fire rings. Those gaskets could have been carefully cut out in pretty curves and it would make no difference in the gasket performance - again - that's uncompressed gasket area: It has no part in any sort of cylinder sealing. Same as the piece of gasket that pooches out around an old thermostat housing or valve cover flange.

    Coolant has to get past that squashed fire ring, into a cylinder. That happens due to loss of head bolt clamping pressure, not gasket deterioration in an uncompressed coolant area. (Notice the "steam holes" adjacent to the pinholes - ?????) Coolant flows up through those little holes into the cylinder head passages 24/7 during normal engine operation.

    Notice that there is NO deterioration of the gasket material at the edges of the compressed bolt holes or the oil drain ovals................

    Forget the pinholes in uncompressed areas - look at the highly compressed areas just outside of the fire rings - see any 'pinholes' there ????

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