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Old 10-27-2007, 12:13 PM   #31
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Old 10-27-2007, 02:02 PM   #32
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Quote:
Originally Posted by firebuick
also if dex is so bad why is the gasket deforme around the intake port also where there no coolant granted not as bad but the are still deforme .
That is explained in his write-up.
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Old 10-27-2007, 02:11 PM   #33
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Quote:
Originally Posted by bonnie94ssei
Quote:
Originally Posted by firebuick
also if dex is so bad why is the gasket deforme around the intake port also where there no coolant granted not as bad but the are still deforme .
That is explained in his write-up.
Yes, that is very well explained in my web page. Not only that, but if HEAT is the problem with them, why are the intake ports collapsed when they're the coolest area of the LIM gasket?

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Old 10-27-2007, 03:05 PM   #34
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From the State of Missouri'* class-action lawsuit against GM:

Quote:
The GM class actions allege that Dex-Cool used in certain 1996-2000 model year 4.3 liter vehicle coolant systems results in sludge, and, that the intake manifold gaskets (IMG) used in certain models and model year GM vehicles are incompatible with Dex-Cool.
Quote:
The certified lawsuit breaks down the Class Members into two sub-classes:
1. All Class Members who purchased or leased a GM vehicle in Missouri with a 3.1, 3.4 or 3.8 liter engine that was factory-equipped with DEX-COOL, and,
2. All Class Members who purchased or leased a GM vehicle in Missouri with a 4.3 liter engine that was factory-equipped with DEX-COOL.
The sub-classes are named “Gasket Sub-Class” and “Sludge Sub-Class” respectively.
Quote:
Evidence: DEX degrades the nylon IMG
The court said that all of the above had no bearing on whether it had represented a written warranty or unlawful practice. They appreciated more that the plaintiffs presented evidence that DEX degrades the nylon IMG within the class, no matter of its size or shape. Plus, GM was shown to have issued a TSB to its dealers calling for a replacement gasket made from different material. GM never disputed that DEX degrades the nylon 6/6 IMG.
Quote:
Expert witness: DEX-IMG incompatibility well-known
One of the documents is from a 50-year veteran of the gasket and seal industries. A member of the SAE, ACS (American Chemical Society) and ASTM, the latter of which he served on the D15 coolant committee, he states that he was aware of GM’* 3.1 liter, etc, IMG failures well before learning of the lawsuit. He goes on to say that the gasket’* poor design and incompatibility with DEX was well-known in his industry. What brought up the discussions was GM’* adopting DEX in 1996, which of course led to widespread testing by him and peers. Those companies included heavy duty manufacturers Caterpillar, Cummins and International. He authored two technical papers, derived from thousands of hours of testing, focusing on the effects that DEX’* corrosion inhibitors have on rubber and plastic gaskets and seals, including GM’* IMGs in question. He concludes that the two are incompatible because DEX OAT inhibitors degrade both silicone and nylon, of which these gaskets are made.


For more specifics, the IMG is described as Nylon 6,6 carrier, 33% glass filled, injection molded, single silicone sealing bead. This man felt the IMG was not a good design to begin with, and then the inhibitors start attacking the weakened carrier. Evidently, because the silicone sealing bead is not molded over onto the carrier, the carrier is in direct contact with the DEX. Tie that in with no compression limiters, needed to maintain gasket integrity (see photo above), to begin with and that, according to the expert, is why the gasket is prone to fail.
I'm actually glad I found that after I wrote my web page. My approach was to prove to myself what the most logical explanation was.

It'* tough to change your way of thinking when you're already mentally set rock-solid with another conflicting belief. Everyone here that has one opinion or another should research it instead of jumping to conclusions based on what others have told you.
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Old 10-27-2007, 04:36 PM   #35
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Great find Bill.
Now there is no denying that the problem is real and the problem is DEX

I hope that ALL of our club gearheads now agree and can school our less knowledgeable members of this fact.
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Old 10-27-2007, 09:35 PM   #36
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Yikes, that stuff is pretty nasty. I wonder why our work trucks seem to have no issue with it. Do the Vortec V8s have better gaskets than the 3800s?
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Old 10-27-2007, 10:04 PM   #37
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It depends on WHEN the gaskets or engines were made. And they are only 'more resistant', not 'bulletproof'.

It'* when DEX turns acidic that is the issue. My neighbor had no problems with his Z71 Tahoe until he sprung a small leak on a heater hose connection. The DEX turned acidic, and ate his heater hose stovepipe connection inside the LIM. Yes, it was Nylon also.

I fished out the pieces, and he flushed out the DEX, but the damage was done. He'* eating coolant at a very slow rate now. Bad for him, he just moved to Portland, so I won't be doing a 'freebie' for him this time.

That Missouri case I quoted above is the first time I've seen an article on it that divides the problems into two categories. Sludge being one (clogging the radiator, and the car overheats) and LIM gasket failures.
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Old 10-27-2007, 10:52 PM   #38
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ok im finally gonna comment here.......

after talking to my dad, (GM/ASE FWIW)

the DEX is ok in a car/truck that is driven on a daily basis, it wont sludge up, and wont be harmful.....

now keep in mind that my father has seen more and worked on more 3800'* that had Dex in them than 10 members combined.....he just LAUGHED at the claims that he was reading, that the dex was the only reason the gaskets were collapsing....it was quite funny actually

he was around for the Series 1 and the Series 2.....he told me that has seen gaskets on the 95 S2s that were WORSE than the Dex S2 cars, and they had the GREEN coolant in then proven by service records


and here is where my father brought up a very important point.....

lets remember what the Service Intervall for the Dex is



if the service intervall on Dex says 5 years or 100,000 miles....how many cars that have all these problems the cooling system serviced???? chances are NONE....so lets consider that one also...that would be like using Dino oil and running it for 30,000 miles with out an oil change....will you have problems?, you bet your ***...if you dont maintain the Dex its gonna sludge, but if you service it well duh....


at the end of the day, the simple fact is this....

a properly maintaied service intervall of the Dex will not cause problems in a car....
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Old 10-27-2007, 11:05 PM   #39
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Good write-up Bill. I'm doing my LIM gaskets in the spring and will be curious what they look like. Car had Dex in it for 107,000 when I flushed and switched this spring even though the Dex was clean and clear. I will take pictures of my gaskets and I think you should start a Sticky post asking everyone that replaces their LIM gaskets to photo them and post them with comments about condition etc. that may not be obvious in the photos. The more data you have, the better.
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Old 10-28-2007, 12:00 AM   #40
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I think that heat may play more of a factor than you think, willwren, but not as much as BillBoost asserts either. Heat speeds up chemical reactions.
In other words, the heat of the motor is speeding up the rate at which the acidic DEX eats the carrier material. And as the material is chemically altered, the heat may have a direct effect upon the altered material, contributing to it'* eventual failure from what does visually appear to be heat damage. Several factors may be involved here guys, but I do believe that DEX is the linchpin in this little chain of events.
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