dex-cool

[dmfco]

I have a 97 chevy venture. I have owned it for 5 yrs. just now reaching 90,000 miles. I am a mechanic I know of the problems concerning dex-cool antifreeze. I have worked on several related problems due to dex-cool in my driveway for friends. Cooling system sludge, intake gaskets, blocked heater cores and valves, head gaskets, sludged oil pans due to obvious head and intake gasket leaks, oil pumps, and so on. Going back to my 97 venture, I have always gave up to date and regular maintenance on my venture. Just the other day it starts acting a little funny, I went out to check the coolant, its sludge, I flush and change the coolant. Dex-cool continue to sludge again I replaced the oil and coolant. My belief on this situation is that the engine seal gasket. plugs allowed a bi-chemical oil, fuel, vapor, and so on to contaminate the cooling system which sludges the engine. I am now in the process of replacing my engine due to a loss of oil pressure. Which I am going to document. I believe once the engine became sludge in the cooling system, it insulated the block from transferring heat properly to the water which in return caused hot spots in the block. Which caused the breakdown in the oil which caused the block in the oil pump. Being it is aluminum block and it transfers heat and cold properties efficiently this is all easily inderstood . Now add to the fact that this cooling system has became completely faulty at doing its job due to the sludge and the dex-cool properties. We recognize the fact that the dex-cool has sludged, the radiator has sludged, heater core, heater velves, and general cooling passages, add to this the resistance that the water pump has taken on due to the sludge, which I believe causes premature failing of the water pump and cooling system. Which obviously explains the end of the means for the engine. I believe that these can be chemically proven easy enough in a lab by breaking down the dex-cool. Then submitting it too the various bi-chemicals created by the engine relating to different metal properties, exhaust gas properties, oil, fuel, and then possibly by someone going down to get a lube, oil, and filter chnge and them topping it off with the wrong anti-freze. Let's get this stuff into a lab, let's shake it up, stir it up, and let's see what the true sastitics of this is, there are too many people and too many things to say this is not happening. Thank you for your time and please contact me and let me know. I wil be pulling the engine out this weekend and having the radiator flushed, would anybody like any of this stuff? i think it is readily availabe any where you go. I would be glad to help if I can, I still owe 3000.00 on the van and it is going to cost me 1200.00 to attempt to resolve the issue and I will not be running dex-cool and I believe if someone runs dex-cool from their car they should not void of their warranty. I believe other anti-freeze out there have alot better track record for there age than dex-cool could even attempt. Thank You

http://www.girardgibbs.com/dexcool.html
Thats where that letter went.
Pass it on ...... Thanks Kc Joplin Mo.

[cdru]

The problem isn't with Dex-Cool directly, it's with people not paying attention to their fluids. Dex-cool starts to gunk up when air is introduced into the system. People with leaky coolant systems or those that don't keep the overflow tank properly filled usually are the ones who end up having a large air pocket at the top of the radiator. So the gunk starts forming, cycling through the system.

The leaking gaskets are not the fault of the problems with Dex-Cool. Dex-cool problems are the result of the leaky gaskets (amung other things). GM has a definite problem with the early 3.1 and 3.4 engines. But blaming it directly on Dex-Cool is just trying to find a scapegoat to blame. In reality, they were just poorly engineered.

[bigbadrat]

dex-cool is total garbage.they claim it will last up to 100,000 miles which is bull.there is some kind of chemicial in that stuff that justs sluges up and makes big time problems.thats the reason head gaskets blow all the time becasue it eats at the material.there is another antifrezze out there that is eqaul to dex-cool but better.i have never seen regular antifreeze sluge up when it gets air in the system.where did u come up with that being for dex-cool.

just all in all dex-cool is junk and i wouldnt ever put that in any of my cars.just my

['97ventureowner]

Actually cdru is correct. The big mistake GM made was saying the Dex Cool was good for 5 yrs/150,000 miles. This caused a lot of people to "neglect" their cooling systems since it appeared they didn't have to service it that often. As a result air infiltrated the cooling system causing sludge to build up in the system. Dex Cool should be treated as the old ethylene glycol antifreze, and needs to be drained roughly every 2 years, or 30,000 miles, along with a cooling system flush and replacement of the radiator cap. The cap has been known to fail and let air into the cooling system as well. Using a new cap is insurance against this from happening. Vehicle owners should also keep a vigilant eye on their coolant resivoir tank and not let the level go below the reccomended lines on the tank. Constant refilling of the resivoir tank indicates a problem, which needs to be looked into immediately for the cause.

[gls02]

What I have noticed on my Silhouette is that the hose going into the over flow tank goes through a grommet. The grommet does not make a good seal and the coolant slips by the grommet with the motion of the van. Now, the position of the over flow hose into the tank is such that when you hit your brakes the coolant is sloshed forward and gets by the grommet. I have noticed dried "pink" Dex-cool on the outside of my tank around this grommet. I keep and eye on my reservoir tank and add very little Dex-cool to keep it at the proper level. I should just put a sealer around the grommet and be done with it.

[lash laroo]

you have to be carful not to mix the green with the red, i have been told by a GM engine designer about 2 years ago that doing so will cause the rubber hose's to rot, but at the same time prestone now has a coolant that can be mixed with any colour coolant, and it's green

[cdru]

Mixing the two won't cause your hoses to rot. It will however introduce sillicates into your antifreeze. The whole point of Dex-cool is to remove (or at least greatly reduce) the silicates which can drop out of the solution and form large deposits, eventually clogging the system.

[diesel1962]

I have found out that when Dex Cool forms a "sludge" It is hard to flush out of a cooling system.What kind of chemical would you use?Diesel 1962....

[MT-2500]

Like Cdru said
Dexcool is not the problem it is the way people use it.
If your car came with Dexcool put dexcool back in it.
It is made and designed for the modern engine.
The only problem with it is it does not last as long as the manf. says.
Just like the 100k before tune up.
It should be changed ever 50K or 3 years and you will have no problems with it.
MT

[RahX]

what you need to do if you have a dex cool system is #1 regular flushes like what has been mentioned on here already. #2 use some type of flush cleaner stuff to break up the deposits and whatnot in the cooling system. #3 a good power backflush should dispel any crap in the main cooing system. this leaves the heatercore which youre going to have to flush manually. if you dont re-use dex cool make sure the stuff you use is silicate-free. its friendlier to the iron/aluminum part combinations of your engine. the block is iron as opposed to aluminum. your engine is basically a battery, two disimilar metals in the presence of a catlyst. thats what causes pitting and stuff in the cooling system.

[cdru]

Originally Posted by Huney1

Very interesting RahX, and I wonder if that is what is causing the intake manifold gaskets to fail setting up a sort of electrolosis eating into the gaskets.

Repeat after me:

DEX-COOL DOESN'T EAT GASKETS

Dex-cool is not the cause of the gasket leak, a poorly designed gasket causes gasket leaks.

[Glen_T]

It would be very interesting for someone to post good quality pictures (close up) of a failed intake gasket. I''ve looked at many gasket designs over the years as an engineer, and I'd be happy to put my two cents in as to the design of the gasket and the cause of the damage (as much as could be determined via a picture)....Glen

[swp5767]

A mechanic friend of mine calls it Death-cool.

He suggested after the 5 years of 150k miles are up and its time to change it, to go with Prestone or something other than Dex-cool.

[MT-2500]

You need to Service it.
As stated at the first of this post it is not the coolant you use it is the service that you give it.
Green yellow red or orange or dex cool.
If you go with a 3 year or 50K service on the cooling system you will have no problems with any of them.
Mt

[cdru]

Originally Posted by Huney1

From a service standpoint, the Venture is so poorly designed, in my opinion, GM designed it so the owners could not or would not work on it. For instance, whoever heard of having to, "roll an engine," to install new plugs?

Have you owned other minivans? Each one has their quirks. My parents owned a Astro a long time ago that required removing some dash compoents and the firewall to get to the rear of the engine. Rolling the engine forward is nothing new. Many other makes using the 3400 require it. I beleive some of the 3800 require it (Grand Prix for instance but down quote me on it).

Originally Posted by Huney1

Cdru proffeses again: "The whole point of Dex-cool is to remove (or at least greatly reduce) the silicates which can drop out of the solution and form large deposits, eventually clogging the system." VERY, very, very rarely does Prestone cause jelly-like clogging, but jelly clogging seems to be a prety common problem with DexCool.

Properly maintain it and it won't "jelly up" as you put it. Neglect it and other problems effecting it and it will cause problems.

Originally Posted by Glen_T

It would be very interesting for someone to post good quality pictures (close up) of a failed intake gasket. I''ve looked at many gasket designs over the years as an engineer, and I'd be happy to put my two cents in as to the design of the gasket and the cause of the damage (as much as could be determined via a picture)....Glen

When mine original one failed, it was obvious where it was leaking from. The orange sealing gasket surface was crushed in several places allowing it to leak. Sorry I don't have any pictures of it.

Originally Posted by Huney1

Otherwise, I don't believe anyone can say unequivocally what is or isn't causing the gasket failures. It isn't feasable, but if we ran pure 100% plain water in the system, would the same gasket fail same as a system with DexCool?

The difference between the new and old gasket styles is the addition of the metal inserts around the 4 bolt holes, preventing the gasket from being crushed. Once the updated gasket is used, the instances of intake manifold problems drops signifiantly.

And yes, if you had used water (or even your precious Prestone antifreeze) the same problem would have occured, presuming the water didn't boil off on it's own or otherwise evaporated.

Originally Posted by huney1

Another question comes to mind; Did GM use that gasket material JUST on the 3.4 engine, or did they use the same material on the gaskets for the four cylinders and V8's? However, if it is the same material used in all their engines then there is something unique in the 3.4 causing gasket failure. If it was NOT the same material, then why did GM use a different material in the 3.4 gaskets and why did they chose to fix something that wasn't broke?

All GM 3100 and 3400 engines used this gasket from 96 to 2003 before it was redesigned. 4-cylinders are inline, so they are a drastically different style of engine so the same situations don't apply. The 3800 is a 90 degree engine, as compared to the 60-degree engines the 3100 and 3400 engines are, so the situation is different as well, different model of gasket. It also uses a plastic intake (which is prone to cracking/leaking as well). I do beleive however that the 3800 intake gasket has a similar problem but it's not nearly as prevelent. GTP Dad might be able to say more though.

It's not necessarily a gasket sealing material problem in itself, it was how it was designed that allowed the leak. AFAIK, that actual physical plastic and/or rubber materials are the same.