Thread: DexCool: anyone else have problems?

I took my wife's 70,000 mile 2000 Bonneville to the mechanic earlier this week because it had developed a missfire, but no computer codes were set off. I checked everything I could and it all looked OK. Upon further inspection, the mechanic found that all of the intake manifold gaskets have been literally destroyed by DexCool. There was some water in the cylinders and oil, but the engine suffered no damage and the intake was not cracked. It still cost over $500 to fix, though. I also had them flush the system and replace the coolant with green antifreeze. The worst part is that GM is not accepting responsibility and refuses to pay for the repairs. When confronted about the problem, GM claims overheating the engine probably caused the problem. I know for a fact that this car has never run hot. I have always bought and driven GM vehicles exclusively, but I might have to think twice before buying my next vehicle.



Nathan

There's been several discussion on the problems although I can't point you to them. My 97 GMC has 100,000 miles with no problems using Dex.

DEX does not like air in the cooling system. From what I remember of discussion, it has to do with the silica content. I had used it in my truck when I did an engine change and ended up replacing hoses on the note of about one a month from them degrading from the inside out....... appearently the silica had to do with some of this because I DID have some air in the system.

Its not GM, its the coolant that is being used.

The solution and recommendation from some engine cats that I know, is to only use this stuff in a closed system. From that point forward I have always used straight H2O and "water wetter" in the race car, and use a slightly watered down glycol mixture in the truck, only because of the fact that the truck will see freezing temperatures..... the race car never will.......

Im an auto mechanic at a reputable shop...

DEX, when it gets old becomes very acidy and eats gaskets..

I tried usuing it in my camaro and instantly developed a bunch of leaks.... after i switched back to green the leaks were gone..

Dex seems to be a thinner liquid kind of like gas and finds its way out of a coolant system fast..

more than likely your problem is the composite intake on the 3.8...not really the coolant......they replace them all the time at the GM dealer I work for......2 reasons...they warp alot and the egr likes to burn through them...so if the mech you took it to didn't replace the intake it will probably do it again sometime soon.....you might be lucky and it was just a gasket though..never know...I cuss the engineers at GM on a hourly basis

We replace GM intake gaskets all the time at the shop I work at,I think its a combination of things..the Dex and crappy gaskets!

I'm in the process of swapping out the intake manifolds gasket on my '96 Tahoe because of a misfire in the #3 cylinder. From the people I've talked to, it's a common issue with the Tahoes and suburbans. Everyone I've talked to hates dex cool, and after laying across my engine bay for 4 hours and not being done yet, I agree with them.

GM redesigned the gaskets for their v6 engines, the change is inevitable for these engines. We do it alot here in GA. Dexcool and Ford extended life coolants have a similar problem clogging cooling systems after extended mileage, we change it to Peak Global coolant to ensure no compatability issues.

My heater core and water pump went on my '96 Camaro when it had 50k miles on it. I've gone to green coolant since.

about 1 year (@1997) after dex-cool was installed in all gm vehicles, i had a 1996 4.3 4x4 blazer come into the shop with no heat. chkd all the usual and called TAN (gm's technical ASSistance network) and they said the cooling system was contaminated with "mississippi mud". over time dex-cool solidifies in the cooling system. since then i have seen blazer radiators weigh @ 70 pounds when removed, pet-**** removed but no coolant, both hoses removed but no coolant. i have had to replace radiators and heater cores in all gm vehicle with dex. at our shop we always flush the dex out with water and re-fill with 50/50 green and water.

the 3.8 will deteriorate around the egr tube in the uper plenum very common - you can even get one at car quest and napa now. personally, i install 1/4" pipe plug in the lower intake coolant passages. this blocks all coolant from going into the intake and throttle body. dex is also very hard on plastic/rubber intake gaskets.

good luck
kevin

I just drained my nova to pull the intake, found a very small amount of mud in the back of the head where it doesn't circulate but otherwise everything looked pretty good, I haven't had any problems besides a leaky radiator, and that's becuase it's a beat up 35 year old leaky radiator. THe gasket (vortec composite plastic/rubber) was a little warped, but no leakage at all. probably 60k on the engine.

i'm a tech for a chevy dealer here in ohio, dex-cool is nasty stuff, it likes to gel up when it gets older. but its not the coolent that took out the intake gaskets its the hot, cold, hot, cold with oil mixed in there on the plastic gaskets. the 3100 and 3400 are the worst for that problem but the 3800 does it too. even the 92+ 5.0L and 5.7L truck engines that had green coolent go out all the time since they also have plastic intake gaskets.

We replace intake gaskets all the time. 75% GM and 25% others.
There is a re-designed gasket and new bolts for those engines (the bolts are the same far as I can tell with some sealer on them). Anyhow, its a poor design and the dexcool doesn't help any. If you want to keep dexcool treat it like regular coolant and replace it yearly (or whatever the normal schedule is for green stuff where you are). It cannot survive 5yrs in an engine any more than the green stuff can. Personally I would remove the dexcool on any vehicle I owned. If nothing else add some Peak longlife instead as it is compatible with dexcool and other longlife coolants (toyota, dodge etc ).
Cheers.

Are we talking generically when saying Dex Cool as there are other brands on the market?

Dexcool is GMs long life coolant (their only current coolant I believe?). It starts out life as a orange/red colour but quickly turns brown, crusty and stinky. GM recommends replacing it every 4 or 5 years, hence the name longlife.
There are other longlife coolants out there though. Dexcool just seems to be far worse than any other. Some of the other longlife show the same issues just not nearly as severe. If the coolant in the system is not green, chances are its a longlife coolant. I would recommend replacing your coolant yearly whether its longlife or not. The whole $10-20 per year is worth it to not have to replace gaskets, water pumps, and radiators.

you need to make sure the coolant level is at the proper level and that the radiator cap/overflow cap is the CORRECT PRESSURE FOR THE VEHICLE and that it is in GOOD working condition.

I have found it is nearly impossible to use Dex-cool in any thing older without leaking or some other not so good side effect. I won't use that stuff anymore in anything that is not under warranty. FRANK

Every car that comes into My shop with Dex-Cool We recomend replacement to standard green coolant. We see it most problematic in mid 90's S-10 P/U and Blazers. The funny thing is one of My customers called a local GM dealer to complain that at 50k miles the had to replace most of thier cooling system because it was so plugged with Dex-Mud, they asked why was he checking his coolant before 100k.

Personnaly I run Evans NPG coolant in everything I have. I was sold for life on the stuff when at Hot Agust Nights in '98 I had the electric fans on My Chevelle quit working while sitting in traffic. Air temp was 105 degrees. I watched in horror as the temp gauge pegged. However, the car never boiled over, had any pinging or any power loss. No signs of running hot at all. It is absolutly awesome!

When we picked the car up Friday, the mechanic said that our problem was traced back to a faulty radiator cap that was letting air into the system. Oxygen and DexCool do not mix well! I still had them flush the system and switch it over to standard green coolant.

Nathan

Originally Posted by Ralph LoGrasso

I'm in the process of swapping out the intake manifolds gasket on my '96 Tahoe because of a misfire in the #3 cylinder. From the people I've talked to, it's a common issue with the Tahoes and suburbans. Everyone I've talked to hates dex cool, and after laying across my engine bay for 4 hours and not being done yet, I agree with them.

Ralph, be sure when you replace the gaskets that you use the newest GM part number of 89017465. This replaces the old gasket with part 12529094. The difference is the new gaskets are still plastic with the o-rings and now have a washer at each bolt hole made into them to prevent overtorqueing. At the dealership I work at, we have not seen any problems out of the new gaskets. Hope this helps and is not too late.