: Thoughts on Dex-Cool and Head Gaskets



abs
07-28-09, 10:11 AM
I've been doing a whole lot of research on Dex-Cool and trying to determine if I want to leave this coolant in my Northstar or pull it out and replace with something like Zerex G05 or Peak Global.

Apparently DexCool can become acidic over time if it is either a) not maintained, or b) exposed to air due to minor leaks in the coolant system. Over time, the acidity of the Dex-Cool can damage all kinds of gaskets. A number of folks who regularly replace head gaskets in Northstars have reported that the condition of the gaskets pulled from cars still running Dex-Cool often appear to be more worn out and rusty than typically seen with cars not running Dex-Cool. One person who has described this pattern is Jake (97EldoCoupe).

Now, we already know for sure that Dex-Cool can severely damage gaskets that have a Nylon carrier. The best description of this I've seen to date is here:

http://www.zillamotorsports.com/DEX/

Also, although nobody knows for sure, the failure mode of our Northstar engine gaskets "may" be in part due to Dex-Cool becoming acidic over time. From what I have read on this message board, one of the more likely theoretical failure sequences could work something like this:

Step 1: the head gasket begins to slightly leak such that coolant makes its way to the head bolts

Step 2: the Dex-Cool is now exposed to air and quickly becomes highly acidic

Step 3: the head bolts start to become loose as the acidic Dex-Cool reacts with the aluminum block and dissolves the aluminum threads in the block

Step 4: combustion pressure places enough force on the bolts that they pull loose from the block due to the weak threads damaged by the Dex-Cool


Why does this happen with Dex-Cool? It appears that the addition of a specific organic chemical called 2-ethyl-hexanoic acid may be a big part of the root cause. As far as I can tell, ONLY GM and ONLY Dex-Cool (and Dex-Cool clones) use this organic acid in the design of the coolant. Ford tested Dex-Cool in one of its vehicles and decided NOT to use Dex-Cool, instead moving toward a Hybrid coolant containing organic additives (but not 2-ethyl-hexanoic acid) while still containing low levels of silicates (like the old green coolants had). A good primer on the various coolant options can be found here:

.pdf
http://www.gates.com/downloads/download_common.cfm?file=MOTORCoolantFeature.pdf&folder=brochure

or .html

http://findarticles.com/p/articles/mi_qa3828/is_200408/ai_n9453107/?tag=content;col1

I realize that some people are die-hard Dex-Cool supporters and others either want to know what their options are (besides Dex-Cool) and/or would like to switch from Dex-Cool to some other coolant which may avoid some of the issues with Dex-Cool. I do not want to start a "flame war" but rather have a meaningful dialog about options besides Dex-Cool for those of us who are interested.

One of the best coolant cross reference matrixes I've found so far is here:

http://www.eetcorp.com/antifreeze/Coolants_matrix.pdf

This .pdf is also attached to this post.

From my research, for anyone who wants to convert from Dex-Cool or a Dex-Cool clone and who also wants to avoid the 2-ethyl-hexanoic acid, I think there are a few options: Zerex G05 (does contain some silicates as well as borates), Peak Global (does not contain silicates, phosphates or borates), Motorcraft Orange (G05 clone), Honda Blue (contains phosphates by no silicates or borates). There may be others as well.

For myself, I've converted one of my two Northstar powered vehicles over to G05 and I may use Peak Global in the other . . .

Andrew

Ranger
07-28-09, 11:05 AM
Apparently DexCool can become acidic over time if it is either a) not maintained, or b) exposed to air due to minor leaks in the coolant system. Over time, the acidity of the Dex-Cool can damage all kinds of gaskets.
Internet myth. How do you get it from the bottle to the engine without exposing it to air? And if this was true, how come all the other gaskets don't fail? How come all the other GM engine don't have HG problems?

Submariner409
07-28-09, 12:38 PM
OMG.....................:horse:




.............and how come every other car in the world, most of which run DEXCOOL or a proprietary variant, don't "eat" gaskets.

abs
07-28-09, 12:46 PM
Hi Ranger -

I don't have all the answers and this was part of the reason for my post, to get feedback from others. Perhaps exposure to air is not the reason Dex-Cool becomes acidic, I really don't know . . . Perhaps it becomes acidic just due to a lack of maintenance. Either way, it still begs the questions:

1. Why take the "chance" with Dex-Cool when other options are available?
2. What causes the aluminum block to deteriorate and "let go" of the head bolts?
3. Do we believe that the ONLY coolant option that will work in an aluminum Northstar is DexCool and if not, then why not change to something with a potentially lower risk of causing issues?

It seems to me that earlier Northstars running on traditional green silicated coolant appear to have a much lower HG failure rate (based on survey on this site and comments from people doing these repairs), so why not switch to something more like that and try to reduce the risk of the HG failure?

Andrew

Submariner409
07-28-09, 12:50 PM
The shift to DEXCOOL began in 1996. I think the failure rate for 97-98-99 is highest in the poll. We are of the opinion that the main problem is metallurgy - casting porosities in the block contributing to weak thread machining. Many pictures and posts earlier in here by AJxtcman on just this subject. Block casting changed in 2000.

abs
07-28-09, 12:53 PM
Submariner409 -

Perhaps I am beating the proverbial "dead horse" here, I hope not, and again, the goal is really to focus on options available to those who may want to switch versus having a debate over whether one should or should not switch. I have had a lot of trouble researching what non-Dex options were available and which ones would be compatible with an existing Dex fill without causing strange reactions, etc. I've only identified a few long life coolants that seem viable and I've already mentioned them.

By the way from my research, very few (if any) other manufacturers beyond GM have adopted DEX or DEX equivalents as their recommended fill. From my research it appears that Daimler, Chrysler, Ford, BMW, Honda and Toyota do not use Dex. I am NOT a coolant expert so I can not guarantee this information is 100% correct, but I do believe it is . . .

Andrew

abs
07-28-09, 01:03 PM
The shift to DEXCOOL began in 1996. I think the failure rate for 97-98-99 is highest in the poll. We are of the opinion that the main problem is metallurgy - casting porosities in the block contributing to weak thread machining. Many pictures and posts earlier in here by AJxtcman on just this subject. Block casting changed in 2000.

Hi Submariner409,

Yes, this is another operating hypothesis which may very well be the case. Having said that, it seems very coincidental to me that the majority of issues occurred starting the years that DEX was first deployed. I realized that DEX cut-over initiated in '96 but I thought factory fill in '96 Northstars was still the traditional green silicated coolant? I also realize that many have described how often times the bolts that "let go" also are wet and the holes/threads badly corroded. If the issue was casting/porosity on its own then wouldn't all of the bolts be affected? And, why do the bolt holes get so badly corroded when the coolant gets to them?

This is clearly a very complicated problem without a single variable causing the failure modes, it may possibly be compounded by many variables interacting in a unique way, as is often said to be the case with catastrophic engineering failures. In some cases, taking just one link out of the chain of events can eliminate (or greatly reduce) the risk of the failure occurring . . .

Regards,

Andrew

Ranger
07-28-09, 04:52 PM
My wife is driving a '96 Bonneville 3800. It's 13 years old and has 160K on it and has never had a leaky gasket. So much for the Dex eating gaskets theory. By the way, Dex is acid based. That is probably what started THAT myth. Don't ask. I don't know what that means, but I am quite sure it is not anything that eats gaskets. Remember, you eat oranges and they have "acid" in them. There is no reason that you MUST use Dex. Use whatever tickles your fancy it you are uncomfortable with it. Using a different coolant will not cause any problems.

abs
07-28-09, 06:37 PM
My wife is driving a '96 Bonneville 3800. It's 13 years old and has 160K on it and has never had a leaky gasket. So much for the Dex eating gaskets theory. By the way, Dex is acid based. That is probably what started THAT myth. Don't ask. I don't know what that means, but I am quite sure it is not anything that eats gaskets. Remember, you eat oranges and they have "acid" in them. There is no reason that you MUST use Dex. Use whatever tickles your fancy it you are uncomfortable with it. Using a different coolant will not cause any problems.

Hi Ranger -

Thanks for the input. I think eventually all coolants deteriorate and become less basic. I've read that some coolants start with a pH in the 10-11 range and others start more in the 8-9 range. The high pH is said to be bad for certain metals - too basic. The lower pH coolants (like DexCool I think) are said to be better for some metals (like aluminum) however, the big issue is how well buffered the coolant is to preserve the basic nature of the coolant. If the pH crosses the neutral mark and goes acidic (due to the buffers breaking down), then the problems may begin in earnest, apparently including damage to nylon gaskets.

I realize that many people have never had a problem with DexCool and the percentage with the issue varies. It does seem however that DexCool may have more very serious issues than other products available . . .

Which non-Dex coolant do you recommend for aluminum engines like the Northstar?

Regards,

Andrew

Submariner409
07-28-09, 07:16 PM
Any old standard green Ethylene Glycol-based coolant advertised as being low-silicate formula or no-silicate formula. Havoline or Prestone in a 60/40 coolant/distilled water mix.

Stop being a chemist and drive your car. Trying to suss out the various coolant chemistries and how they react over time with various metals may lose you some sleep but it won't solve anything in the engine. Or are you an organic chemist with DuPont ???

Ranger
07-28-09, 07:24 PM
The coolant additives are what deteriorate and need replenishment.

I have no recommendations as I don't know anything about them. I seem to recall someone touting G05, but I can't recall who or why. Personally I think it is like oil. People have their favorites, swear by one and at the other, but in the end all that matters is that it gets changed.

JimD
07-28-09, 08:36 PM
The information below might or might not be useful to this discussion. I don't have a dog in this hunt and I don't have a chemistry degree.

What I am is the daily driver of a properly maintained high mileage '98 Seville.

The following was pulled from the Chevron/Texaco web site three or four years ago.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Havoline® Extended Life Anti-Freeze/Coolant DEX-COOL®
Detailed Product Specifications

Havoline Extended Life Anti-Freeze/Coolant DEX-COOL is a
single-phase, ethylene glycol type universal automotive engine
coolant based on a Texaco's patented long life organic corrosion
inhibitor system.

Havoline Extended Life Anti-Freeze/Coolant Pre-Mixed 50/50 DEX-COOL
is a 50/50 mixture of Havoline Extended Life Anti-Freeze DEX-COOL
with deionized water.

Havoline Extended Life Anti-Freeze/Coolant DEX-COOL is a universal
engine coolant that incorporates patented organic acid corrosion
inhibitor technology. This coolant meets both ASTM D 3306 for
automotive service and ASTM D 4985 for heavy-duty diesel service. It
is a nitrite-, nitrate-, phosphate-, silicate-, borate and
amine-free formulation which uses Texaco’s patented carboxylate
technology to provide maximum protection of the six basic metal
alloys found in most heat transfer systems. Since the coolant
contains no phosphates or silicates, hard water deposits in the
cooling system are almost eliminated. The low level of abrasive
dissolved solids in Havoline Extended Life Anti-Freeze/Coolant
DEX-COOL results in improved water pump seal life.

The life of a coolant in an automobile engine is limited by the
corrosion protection ability of the corrosion inhibitors. The main
corrosion inhibitors in Havoline Extended Life Anti-Freeze/Coolant
DEX-COOL have been shown to remain above 95% of their original
concentration after 150,000 miles in automobiles.

This allows much longer intervals between coolant changes without
worrying about loss of corrosion protection. Used Havoline Extended
Life Anti-Freeze/Coolant DEX-COOL was tested in laboratory
controlled corrosion tests for new coolants after it had already
been in service for more than 200,000 miles.

The used Havoline Extended Life Anti-Freeze/Coolant DEX-COOL passed
the ASTM D 1384 requirements for glassware corrosion with results
equivalent to new coolants and also passed the ASTM D 4340 Aluminum
Hot Surface Test for new coolant. Havoline Extended Life
Anti-Freeze/Coolant DEXCOOL represents the next generation of
universal engine coolants.

This coolant is suitable for a five year or 150,000 miles service
life in automotive applications. Note: These products are not to be
used to protect the inside of potable water systems against freezing.

Havoline Extended Life Anti-Freeze/Coolant DEX-COOL is manufactured
from ethylene glycol and a highly effective long term corrosion
inhibitor package based on carboxylate technology. This inhibitor
system eliminates the need for
silicates, phosphates, borates, nitrites, nitrates and amine
additives traditionally used for this purpose. The replacement of
these inhibitors is significant for water pump life because many of
these conventional inhibitors have been shown to be abrasive to
water pump seals. In comparison field tests with conventional
coolants in taxi fleets, Havoline Extended Life Anti-Freeze /
Coolant DEX-COOL significantly reduced the need to replace water
pumps during the 100,000 mile test.

In addition to fleet tests, this product has also been tested by a
major manufacturer of water pump seals, and has been found to be
more compatible with the seals than any other coolant tested.
Benefits:
Meets GM 6277M--GM’s new Long Life Coolant specification
5 year or 150,000 mile service interval
Provides effective, long term corrosion protection for aluminum,
brass, cast iron, steel, solder and copper
Protects against winter freeze up and minimizes the chance of
summer boil over
Compatible with water pump seal materials and minimizes the
formation of abrasive dissolved solids
Storage stable for at least eight years
No silicate dropout or gel formation during use or storage
100% biodegradable in its pure unused form
Excellent heat transfer properties
Nitrite-, borate-, phosphate-, nitrate- and amine-free
Outstanding hot surface aluminum protection
Superior protection in high operating temperatures
Compatible with conventional antifreeze. Dilution with
conventional antifreeze will reduce extended life benefits.

ChevronTexaco recommends that this product not be diluted by more
than 10% with conventional coolants.


© 2003-2005 ChevronTexaco Corp. All rights reserved

Submariner409
07-29-09, 09:42 AM
BINGO !!! :thumbsup:

If you highlight the "Havoline Extended Life..................." line (Firefox) and right-click on the highlight you can call up the Google search for the article.

Ranger
07-29-09, 12:26 PM
Learn something new every day.

abs
07-29-09, 12:43 PM
I'm not really seeing anything I wasn't already aware of in that description. Although there are some technical specs provided, they are not comprehensive as they do not really detail what IS in the mix . . . Also, I noticed that the test results were "lab" based and not "real world" based. Unfortunately, the lab often doesn't represent reality . . .

Thanks for sharing this though - first time I'd seen it.

Andrew

mikelawson
07-31-09, 12:28 AM
I've repaired nearly 30 N*'s and most of them are plain and simple head gasket failures. When I repair I use Prestone's all makes all models. Why not use it? I have seen Dex turn to mud many times, so it's safer to avoid it.

ewill3rd
07-31-09, 08:30 AM
The biggest problem with Dex-cool is all the whiners looking for an excuse to hate it.

The issues I have seen on failures with vehicles using Dex-Cool are specific carline related or maintenance related.
GM never should have started using it because the main reason they did was that customers were crying about having to have their cooling systems serviced.
Now they come out with this new 150,000 mile coolant so people don't give a rats butt about maintenance so they don't do any.
Just like oil, you have to keep it full... stuff breaks, fluids leak. If someone doesn't check the coolant and you have a leak something will break and everyone just loves to blame the coolant.
Regardless of what the maintenance interval is there are things that can affect the systems longevity.

Dex-Cool in any car is exposed to the atmosphere every second of every day. The reservoir has a pressure cap on it, but that allows air in when the system cools down to equalize the pressure. Older cooling systems have an ambient pressure overflow that is living in our atmosphere... der. Lots of stuff becomes acidic in a car. It's a car... you are exploding gasoline in a metal box thousands of times per minute. Exposure to hydrocarbons, thermal cycling, sealants, gasket materials and interaction between metal parts... any one function of an engine would probably kill a human being in even limited exposure... just think about it. And we become shocked and amazed because coolant wears out in less than 10 years? Really?

The head gaskets fail on N* because of a mechanical design issue, not some magical evil fluid.
S10 pickups were bad in the late 90's but I believe that was an engine manufacturing issue, not some horrible reaction to Dex-cool.
C/K trucks were bad about leaking intakes... but that was a gasket design issue, it had nothing to do with the coolant, and the heater pipe fitting would corrode due to electrolysis, not Dex-cool. The list goes on.

Searching for "facts" on the internet and believing everything you read is not "proof".
As stated, if you hate Dex so much, flush it out and use whatever you want. There is nothing wrong with using conventional Green anti-freeze, you just need to change it more often. I have seen green coolant systems eat every vane off of a water pump or tear a hole through a metal housing, it wasn't the coolants fault it was the owner of the vehicle's fault.

Besides I am more worried about the aliens that have been living among us for decades, I read that on the internet too.

Dead horses indeed.....

MrEldo97
07-31-09, 12:31 PM
I agree re the Dex. I remember when I timeserted my N* and got the new factory head gaskets; my reaction was "That's a cheap looking gasket..." I maintain my car by the book and it pulled head bolts at 91,459 miles, clearly little if anything to do with Dex Cool.

ewill3rd
07-31-09, 06:50 PM
And just for the record, I used to blame Dex Cool for all my headaches too.
I have been working for GM since before they started using Dex, and I can tell you based on my experience it has little to do with the coolant and more to do with what it is in and how it is taken care of.
;)

abs
07-31-09, 08:29 PM
Just for the record, I am not a person who believes everything he reads however I tend to be critical and incredulous of most things I'm told, particularly without proof. Having said that, I think it's fair to say that there is a whole lot of proof that GM has had issues with some of their engines running DexCool. It is not "proven" what caused the root problems in these engines but GM did pay out quite a bit of money resulting from the class action law suits. If they weren't culpable in some way, I doubt they would have agreed to pay a penny. Ultimately maintenance is very important for all vehicle fluids and unlike most, I actually change mine.

I've converted one of my Northstars to G05 and I will convert the other one to Peak Global or G05 as well . . . These coolants both seem to have a better reputation and a proven track record without any of the uniquely reported issues associated with Dex-Cool.

Andrew

ewill3rd
07-31-09, 09:15 PM
I think that GMs pay out was more related to an inability to prove no fault rather than an admission of guilt.
It is hard to prove that it wasn't a factor at all.
I wouldn't make excuses of course, I am sure the people that made the decision seemed to think it was a good idea for whatever reason.

I didn't mean to sound preachy or anything. Sorry if I came on too strong.
I certainly respect your decision not to use it.
I hear of a lot of people that changed but don't often hear back as to how the cars are doing.
Be sure to check in once in a while with the results of your choices. I'd be curious to know.

abs
07-31-09, 10:17 PM
Hi Ewill3rd -

I truly appreciate everyone's comments, yours included, I am new to Cadillac's and the Northstars yet trying to maintain two Northstars in a way that will give me years of reliable use. I also realize that many people on this forum know more about these engines than I do, hence the purpose of my starting this post. I had searched the archive and hadn't read much about people switching away from DEXCOOL and if so to which alternative coolants. I did find many posts recommending to just change the fluid relatively often. At the same time, some folks were reporting higher than expected rusting of the head gaskets on engines run on DEXCOOL as compared to other coolants. It is very difficult to know if this anecdotal information means anything since it is not possible to know how these engines were maintained.

I will be sure to check back over time and if my head gaskets, water pump, radiator, thermostat or heater core should go, I'll report back on that too.

Regards,

Andrew

abs
07-31-09, 10:24 PM
I've repaired nearly 30 N*'s and most of them are plain and simple head gasket failures. When I repair I use Prestone's all makes all models. Why not use it? I have seen Dex turn to mud many times, so it's safer to avoid it.

Hi Mike - Thanks for the response. I've considered the Prestone All Makes All Models coolant. From my reading/research (which was internet based and I suppose questionable) it seemed like that Prestone coolant may not truly be compatible with all other coolants AND that it contains 2-EH which is one of the key ingredients that has raised the concerns with DEXCOOL and nylon gaskets . . . As an example, Honda expressly forbids using a coolant with 2-EH as do Ford, Chrysler and Mercedes . . .

Some have asked if I am a chemist, and I'm not, however from the information I've been able to find, the Peak Global product appears to be a product that is truly compatible with all makes all models in that it does not contain silicates, borates, phosphates or 2-EH . . . Here's a quick link:

http://www.peakantifreeze.com/peak_global_lifetime.html

Andrew

Ranger
08-01-09, 10:17 AM
PEAK Global™ LifeTime™ Antifreeze & Coolant - Antigel/Réfrigerant features a patented, advanced organic acid technology that provides guaranteed LifeTime protection - for as long as you own your vehicle!* Its patented inhibitors will provide maximum protection against damaging rust and corrosion in all automobiles and light trucks worldwide, regardless of make, model, year or original antifreeze color.

Isn't that what Dex is?

abs
08-01-09, 02:06 PM
Hi Ranger-

From what I've been able to pick up as I researched these coolants, you are correct in making the statement that both DEXCOOL and Peak Gobal are OAT (organic acid technology) coolants. However, there is at least one, and possibly two, big differences. Peak Global does not use the 2-EH chemical (this is the one that is reported to "eat" nylon gaskets) and, quite possibly, the Organic Acid compounds used in Peak Global may be different/better/newer than those spec'd for DEXCOOL since this coolant can take advantage of advancements in Organic Acid technology from the last 15 years (whereas the DEXCOOL spec is probably about that old). At the end of the day, these are two coolants using similar organic acid technology but they are most definitely not the same.

I hope this helps.

Andrew

Ranger
08-01-09, 03:16 PM
That may well be true. I know nothing about it nor do I claim to other than what I stated earlier, but I AM convinced that nothing is eating any gaskets. I'm with Ewill, this is NOT a coolant issue.

abs
08-01-09, 08:58 PM
Okay. I haven't pulled a Northstar head to know if the gasket looks rusty and deteriorated or not.

However, is it possible, or even probable, that once the gasket begins to leak a little, the coolant entering the bolt holes accelerates the oxidation of the aluminum threads?

Andrew

Ranger
08-01-09, 09:24 PM
Oh absolutely. Once the gasket fails, be it from the gasket or the bolt threads pulling, coolant gets into the bolt holes and then becomes an electrolyte for the galvanic action between the steel bolt and the aluminum block causing corrosion and further deteriorating the threads.

osu411yamaha
08-01-09, 11:07 PM
Wouldnt it benefit GM for their engines to fail at exactly 100k miles seeing as they are giving a 100k warranty? At that point they either get you to buy a new GM or hopefully buy AC/Delco replacement parts. I hate to be the conspiracy theorist, but if I have learned anything up to this point in life its this....If there is room for foul play then THERE WILL BE FOUL PLAY. This doesnt mean everyone is out to get you, but there is always at least one out to get you......Average lifespan of northstar engine=length of GM warranty......Foul play or just coincidence?....Either way it works out for GM........

JimD
08-01-09, 11:16 PM
....However, is it possible, or even probable, that once the gasket begins to leak a little, the coolant entering the bolt holes accelerates the oxidation of the aluminum threads?

I hold the minority opinion that is precisely what happens.

We know there will be oxidation when a ferrous bolt is used in non-ferrous material (aluminum). The battery action that causes the oxidation is predicted by the Table of the Elements. This oxidation is controlled by two measures; one is the protective coating on the threads of the OEM bolts, and; two is the design of the head gasket to keep the bolt hole dry.

When the head gasket fails (for whatever reason) and allows coolant to contact the ferrous bolts and the aluminum threads, an (acidic) electrolyte is now added to the matrix.

Accelerated corrosion - oxidation is inevitable.

I will take this position to my grave unless I see a report from a metallurgical engineer that supports the idea that a porous aluminum block casting allowed the headbolts to "pull loose".

With all due respect to the technicians that have inspected corroded bolt holes, the forensic evidence is not yet on the record.

JimD
08-01-09, 11:22 PM
....Average lifespan of northstar engine=length of GM warranty....

My English suffers at this time of the day so cut me a little slack.

But your position is unsupportable. In otherwords, bullshit.

ewill3rd
08-02-09, 10:52 AM
Jim,
While I find your theoretical model entertaining it has little basis in reality.

The head gaskets fail BECAUSE the bolts pull. There is nothing wrong with the gaskets, the problem is that the bolts pull and clamping pressure is lost.
I think you are talking about "electrolysis" not "oxidation". While the two have similar end results, if you want to split hairs... and it seems many people here do... well I just thought I'd mention it.
Most (if not all) GM engines these days are cast aluminum and have ferrous bolts. The bolts are typically threaded into the water jacket so the bolts are in constant contact with the coolant.
Why then don't all GM engines have head gasket problems?
As stated time and time again this is a problem that was addressed in production by changing thread pitch and bolting. The rest of the design is still the same.

I hate to keep getting drawn into this garbage but I can't just leave all this X-files automotive my crap out there for people to believe.

Its cool if you don't want to believe what I say, but the truth is out there. :lol:

abs
08-02-09, 11:31 AM
Folks -

I think Jim may be onto something, without "splitting hairs", it seems very strange and a very unlikely explanation that the head bolts would hold for years and even perhaps 100k miles and then all of a sudden just "let go". I also have a very hard time believing that so many blocks suddenly had a manufacturing/production issue starting in 2007 that caused them to suddenly be manufactured with porosity issues or lower tensile strength.

Also, I think we are now finally beginning to see head gaskets going on 2000+ MY vehicles, so I'm not sure the change in head bolt pitch is necessarily the long term solution.

My fundamental point is only that if it is true that DEXCOOL turns acidic (pH below 7) when exposed to air for a long period of time, as would occur with a small/slow leak past the HGs, that it may very well be the underlying cause of the head bolt hole thread damage. IF that is true, then it makes a strong case to switch from DEXCOOL to a different coolant which is less likely to cause that problem (less likely to become acidic when exposed to air).

Some have argued that the DEXCOOL in our Northstar engines is always exposed to air on a regular basis. I'm not fully convinced of the validity of this comment. Although it is true that there is a small quantity of air contained in the expansion space in the small secondary tank, the entire system is designed to be sealed and closed. If it is true that air reacts with some of the buffers in the DEXCOOL, it may well be the case that there is a sufficient concentration of buffers to handle the reaction with the air in the reserve tank and keep the coolant basic. The behavior of the coolant may be very different when exposed to air for a long period of time with an unlimited quantity of air to react with. I have not tested this point to validate it, I am simply sharing "claims" I have read about in my research, however it would be easy enough for any of us to test this. I do know for sure that GM has recommended that people who own vehicles with engines covered by the lawsuit were told to replace their radiator caps and to make sure that the coolant system was completely air tight. Also, cars equipped with DEXCOOL from the factory all have sealed, air tight, secondary reserve tanks as compared to the old style which was open to the air. I think this further supports the idea that DEXCOOL has issues when exposed to the atmosphere for an extended period of time AND that GM was aware of that fact from day 1.

One other important point I'd like to share. As I was doing my research on DEXCOOL, I learned that it takes quite a few thousands of miles of the coolant being in the engine until the additives become effective. Now, I don't claim to know how many miles or the details of how this works, however if this is an accurate point, then it seems to me that frequent changes of DEXCOOL may be more detrimental than beneficial. It is my understanding that one reason the G05 coolants have "some" silicates added is to provide immediate protection until the OAT components become active. This may provide a partial explanation for why some of the head gaskets appear "rusty" or "worn" when removed. The vehicle may in effect be operating for some period of time without any real protection . . .

Also, if DEXCOOL is so wonderful, how come every other auto manufacturer on the planet has flat out rejected that coolant? Ford actually tested it in one vehicle for a few years and concluded they would not deploy DEXCOOL in another vehicle ever again (due to gasket issues). To the best of my knowledge, they are now (and have been for quite some time) using a G05 spec Motorcraft coolant.

Simply put, there ARE some issues with DEXCOOL and I'm unsure whether frequent changes of this coolant are sufficient to truly address the known issues.

The discussion and range of opinions being expressed in this thread, and also in this forum, most broadly proves to me that nobody definitively knows the underlying failure mode and sequence for these head gasket failures. Given the apparent uncertainty and the possibility that DEXCOOL MAY be playing some part in the overall failure of the head gasket (either through damage to the gasket itself or to the head bolt hole threads or both) the question I'm asking is simply this: "Why not switch to a different coolant with a proven track record and potentially less risks associated with it than the DEXCOOL?"

I've listed at least two specific coolants, both of which are "long life" and from my research it seems that neither of them suffer from either the concerns typically associated with DEXCOOL or any other new issues not associated with DEXCOOL.

Andrew

Ranger
08-02-09, 05:01 PM
Andrew, all that sounds logical and could be true, but you have to ask yourself, why not ALL GM engines then? As I said earlier, my wife's '96 Bonneville has 160K on it and never had a gasket problem AND it does not have a sealed reservoir. It expels ambient air with every heat cycle and draws in fresh air with every cool down. The coolant in the tank is also drawn into the radiator with every cool down and expelled into the tank with every heat cycle. Under your theory, that stuff should be even more acidic than what is in the Northstars. You also have to ask yourself why the thermostat gaskets never leak or the water pump gaskets? There is NO problem switching coolants if you are leary of Dex and I would do so in a New York minute if I thought there was a problem. I just don't see the problem. Why only Northstars and why only head gaskets?

abs
08-02-09, 10:31 PM
Hi Ranger -

I am the first to admit I don't have all the answers.

Was DEXCOOL the original fill on your Bonneville? Are you also the original owner? I only ask because if not, then perhaps the gasket was upgraded before you got the car . . .

By the way, I know that car well and like it very much. I have owned two 1995 Buick LeSabres which are basically the same drive train and chassis with softer suspension tuning. They both had the open reservoir and were filled with traditional green silicated coolant when I got them.

I do know that the 3.8 engine is a cast iron block and head so a very different metallurgy than the Northstar. Your point about water jacket gaskets and such may simply be that the materials they are composed of are not reactive with DEXCOOL. I know that those kinds of gaskets are sometimes paper, rubberized paper, cork, etc. I don't know what they are on the Northstar or the 3.8L off hand. I do know that DEXCOOL is said to have issues with nylon gaskets, primarily when the DEXCOOL turns acidic, and when they are not properly protected from contact with DEXCOOL (like the lower intake manifold gasket on the 3.8). Apparently the redesigned lower intake manifold gaskets for that engine are either made of nylon and protected by teflon or are made of completely different materials now.

My guess is that you have always maintained this car well and probably changed the coolant regularly and before it became acidic. This as it seems to me that any lack of maintenance of the DEXCOOL risks causing issues . . .

Andrew

Ranger
08-02-09, 10:35 PM
Factory fill was Dex. I bought the car with 25K on it.

ewill3rd
08-03-09, 06:33 AM
:histeric:
This thread is just awesome.

BTW... NO cooling system is "sealed".

The "pressure" cap maintains approximately 15 psi during hot operation.
MOST cars have a reservoir that is OPEN TO THE ATMOSPHERE.
The REST of them have a negative pressure relief that allows AIR to re-enter the system when the pressure falls off.
The system CANNOT be "sealed" or things will begin to explode under operation.
Some portion of the Dex Cool is always exposed to the atmosphere.

Yeah, magically the same engines, made by the same company at the same plant with the same specifications could be subject to the same failure. Pretty remarkable I know, but it is possible. Amazing to me also is how this issue severely declined after GM looked at it and made changes to the block in production, including thread pitch. That's probably just a coincidence though.
LS engines have been in production with an aluminum block since '97. I can count on zero fingers how many head gaskets I have seen fail yet they use the same coolant.

While I find this episode of mythbusters entertaining, I think I'll pass on visiting here again.
It is obvious that several have convinced themselves that the sky is indeed falling.

Actually you know what it is that is causing the headgaskets to go? Global warming.
Yep, that's it.

Okay so you think Dex Cool is to blame and you want to use a different coolant. Go ahead, nobody is stopping you. In fact it might be the greatest idea since television.

I'm sorry.. I didn't mean to interrupt all this meaningless speculation with actual facts.

Please continue....

I'm out. :lol:

mikelawson
08-03-09, 01:18 PM
I have to disagree with many of these posts based on my personal experiences. I will post some pics of head gaskets and i can guarantee that it's more of a head gasket issue than a bolt pulling issue. I am almost sure the head gasket fails first, leaking a little antifreeze in the bolt holes (meanwhile car still runs fine and not overheating because the clamping pressure is not allowing any combustion gasses into the cooling system) but when the catalyst (antifreeze) sits in the bolts holes the galvanic reaction takes places and eats away the threads in the block, and we all know what happens next :). Almost all of the head gaskets I've pulled off have been destroyed by lack of cooling system maintenance. Let's not forget that these are open deck blocks where the 3.8's and SBC's are all closed deck. You don't have the amount of gasket/antifreeze surface area contact as you do with open deck blocks. I will post some head gasket pics later.

jeffrsmith
08-03-09, 04:47 PM
Let me help. These are pics of my HGs that let go at 92K. Thought I would throw in a couple of pics of the Head Bolts as well.

http://i292.photobucket.com/albums/mm30/jeffrsmith6/caddy/Caddy_2/DSC_0010.jpg


http://i292.photobucket.com/albums/mm30/jeffrsmith6/caddy/Caddy_2/DSC_0023.jpg

http://i292.photobucket.com/albums/mm30/jeffrsmith6/caddy/Caddy_2/DSC_0024.jpghttp://i292.photobucket.com/albums/mm30/jeffrsmith6/caddy/Caddy_2/DSC_0034.jpg

http://i292.photobucket.com/albums/mm30/jeffrsmith6/caddy/Caddy_2/DSC_0021.jpghttp://i292.photobucket.com/albums/mm30/jeffrsmith6/caddy/Caddy_2/DSC_0013.jpg

http://i292.photobucket.com/albums/mm30/jeffrsmith6/caddy/Caddy_2/DSC_0007.jpghttp://i292.photobucket.com/albums/mm30/jeffrsmith6/caddy/Caddy_2/DSC_0009.jpg

abs
08-03-09, 05:07 PM
Boy, those gaskets sure look rusty and deteriorated - why?

Submariner409
08-03-09, 07:10 PM
:sneaky:.........actually, not bad for 95K head gaskets. Considering the condition of some stuff we pull out of Olds 455's and GM 454's at 100K.

Head bolts, head studs, fabric gaskets, copper gaskets, stainless gaskets, copper O-rings. All go sooner or later. Try to get the remains of a broken head bolt out of an Olds 455 iron block - WooHoo !

What you don't see is the open deck Northstar design which is hidden by the gaskets, but you can imagine the narrow cylinder seal area by looking at the gasket depression around the steam holes.

So.............which came first: The chicken or the egg ???

:horse:

ewill3rd
08-04-09, 08:16 AM
:pop2:

mikelawson
08-04-09, 12:24 PM
That's about what they all look like. If the block was the problem, the gaskets should look OK. It's obvious those gaskets couldn't seal anymore. Most naturally aspirated engines are open deck, but I bet the supercharged 4.4L Northstar won't experience this issue.

themadwacker1
08-04-09, 01:41 PM
:pop2:

:tard:What’s a head gasket?:aj:

Submariner409
08-04-09, 02:49 PM
Someone please Google "open deck cylinder block" and compare the Northstar block construction to, say a GM 454, Chevy 327, 350, Olds 455 - many other cast iron "closed deck" blocks.

Taspeed
08-25-09, 01:38 PM
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.

osu411yamaha
08-25-09, 03:30 PM
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.

mtflight
09-10-12, 04:49 PM
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.

CadillacLuke24
09-11-12, 02:19 AM
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 :D

mtflight
09-11-12, 09:47 AM
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 :D


See this article (http://www.imcool.com/articles/antifreeze-coolant/GMdocs/dexcool2007-5.7L-IMG.htm).

CadillacLuke24
09-11-12, 12:19 PM
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.

mtflight
09-11-12, 12:39 PM
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?

CadillacLuke24
09-11-12, 02:37 PM
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.

mtflight
09-11-12, 02:48 PM
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.

Submariner409
09-11-12, 04:07 PM
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¢ .

mtflight
09-11-12, 05:46 PM
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://i1218.photobucket.com/albums/dd407/thejumpsuitman/102_0657.jpg

http://i1218.photobucket.com/albums/dd407/thejumpsuitman/102_0658.jpg

http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/255018-98-etc-head-gasket-project-started-4.html#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?

CadillacLuke24
09-11-12, 07:17 PM
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.

mtflight
09-11-12, 08:33 PM
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?

Ranger
09-11-12, 08:42 PM
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". :bonkers:

Submariner409
09-11-12, 10:33 PM
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 ????

mtflight
09-11-12, 10:45 PM
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?

Submariner409
09-11-12, 10:58 PM
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.

CadillacLuke24
09-11-12, 11:43 PM
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.

mtflight
09-12-12, 12:29 AM
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.

mtflight
09-12-12, 12:36 AM
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.

CadillacLuke24
09-12-12, 12:18 PM
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! :thumbsup:

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?

Ranger
09-12-12, 02:52 PM
Sub brings up a good point that I hadn't considered. :hmm: Back to square one with the chicken and the egg. :bonkers: I'm just gonna change the coolant (Dex) every two years and pray to the Northstar Gods.

CadillacLuke24
09-12-12, 05:55 PM
And if the HGs fail I know Jake's phone number.

Ranger
09-12-12, 09:00 PM
Joe is just down the road from me (should the need ever arise).

mtflight
10-16-12, 08:01 AM
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! :thumbsup:

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.

CadillacLuke24
10-16-12, 11:31 PM
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. :duck:

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

Submariner409
10-17-12, 06:59 PM
Bummer. "The lady in front of" you would be happy to know that I shoot and eat the damn gray fuzzy-tail rats.