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Breadfan
03-08-2005, 07:26 AM
I'm just curious if it has been decided that Dexcool has a gasket-eating property to it. I know for awhile everyone thought the LIM problem on our cars was related to Dexcool...but then as time went on it seemed many changed their views and felt that it wasn't really Dexcool's fault but just a bad design on the gasket itself. (That being said the new gasket design doesn't seem much better from what I've read...)

Why am I bringing this [dead horse] up? My mom has a '95 Suburban 4wd with the 350. Recently she had her waterpump serviced (maybe 6months to a year ago), and the service station flushed her cooling system and replaced the green stuff with Dexcool.

Over the weekend she found out her car is leaking coolant. Guess where? The intake manifold.

Not entirely sure if its the manifold gaskets or possible the rear seal(?) at anyrate it'll have to be pulled. (If I don't do the job myself I'll ask her to have whoever does it return the gasket to her so we can see where it failed.)

Granted the engine does have about 150,000 miles on it, I can't help but wonder if this gasket failure has anything to do with the Dexcool. (Luckily it appears to be leaking out of the engine rather than into it...)

Hence the reason I'm wondering if we're certain or not that Dexcool DOES eat certain types of gaskets.

95-GT
03-08-2005, 07:29 AM
I don't think that it is Dexcol that is eating away at the gaskets, but rather the gasket design itself. On ALL cars that I have worked on, the gasket was crushed causing it to break.

GAGTSCTGuy
03-08-2005, 07:33 AM
Dexcool has been in other GM cars of mine(and others in my family); '04 Grand Am GT, '99 Malibu 3100, '98 Sunfire 2.2L, my Grand Mothers 99' Grand Prix 3800, not sure what the bird has in it, but its probably Dexcool.


The Malibu was the only one with the LIM failure. 2003+(except some 03's, like 5 I think) Grand Ams don't have LIM failure BTW....

Breadfan
03-08-2005, 07:35 AM
Oh, BTW, engine is all original never rebuilt, so its the original gasket torqued from the factory I believe...

On second though...I believe she did have a leaky heater hose replaced though, I'll have to ask her for the work order from that to see if they removed the intake manifold. Could be if thats the case they didn't torque correctly...

Anyway if the manifold wasn't removed I've not heard of small block chevy's having the problems we have, so I'd be curious if Dexcool and her older style gasket was to blame. (On the same note my dad's 99 Camaro has nearly 150k as well on the LS1 and Dexcool, no leaks, no problems.)

BTW nice 'Stang...I don't know about you but I think those 5.0's are some great engines. I got 196,000 on mine and still running strong, no dexcool and no leaks! :)



Regarding leaks on other GM cars with dexcool, as far as I have read Dexcool was only blamed for eating certain types of gaskets with specific materials. So not all GM cars would be affected, but possibly older style gaskets or incompatible gaskets would be. Also the 2003+ are using the new gaskets - I've heard others say they've replaced theirs with the new style only to have problems later on. Maybe that's a torquing problem then?

GAGTSCTGuy
03-08-2005, 07:55 AM
I'd be happy if I get to 10+ years/150K on stock gaskets myself. But that's just me

Best bet is probably just to change the gaskets, torque to spec, fill it up, and keep an eye on it, cheap solution. Can't hurt, you might want to check some other seals and stuff while your at it, 150K might be a good time to do some maintenance

Malaclypse
03-08-2005, 12:14 PM
Dexcool didn't have anything to do with that gasket failure. 150k and 10 years is a LONG time to go with intake gaskets on those motors. Also, since the water pump was leaking, the rest of the cooling system wasn't seeing full pressure. So whenever the first leak was fixed, the next weakest link in the system gave out.

Breadfan
03-08-2005, 12:51 PM
Ok, that's why I was asking. The thing is though, I've had all this anti-Dexcool stuff put into my head from owning a GAGT...now should that change? When we do this job and flush the system, what should we put in? Green or Orange?

2000GA
03-08-2005, 02:23 PM
the 350's have intake gasket problems too, my dad replaced his at 58k.

mcgrady
03-08-2005, 02:39 PM
Found this on the internet:

"There is probably more misinformation, conjecture, and outright BS on the internet about DexCool coolant than any other single automotive product ever made.

It is compatible with regular coolant, you just lose all of the long life properties if you mix them. It does not "react" and sludge does not come from mixing them. - sludge, we will get into that.

It does not cause leaks it does not eat gaskets any more than green (slilicated coolant) does. It does tend to clean off silicate deposits that plug leaks in older systems that have had silicated coolant in them. And that brings up another reason to use DexCool, - if anyone here has ever actually taken apart an engine that had silicated coolant in it for years you will find a white flaky coating on the inside of the cooling system. That coating is silicate that is there to protect the parts from electrolytic contact with the coolant. This barrier is also a barrier to heat rejection - so why would you want a coating of silcate between the heat and the water on your high performance car? You wouldn't. DexCool actually treats the aluminum in the engine through a process similar to the process that is used in bluing a gun barrel to help prevent corrosion of the metal. It does not leave a thermal barrier on the surface it bonds to the first couple of microns of metal in the aluminum components to protect them from corrosion. In addition, the silicate is a hard mineral that is loose and floating around in the cooling system (those flakes break off and circulate around randomly). The flakes can get into the seals in the water pump and cause them to wear out and fail - this was one of the prime reasons for GM going to DexCool in the first place.

It can be more agressive at forming sludge in the closed (pressurized) part of the cooling system if air gets trapped or is allowed into the pressurized side of the cooling system. This issue is easily resolved by fixing the source of the unwanted air. You don't want air in there anyway so getting it out is a good thing. The most common part that causes air to get trapped in the system is a bad radiator cap. GM got a bazillion caps from a company called Stant that leak air and that hasn't helped the situation. Too bad, because Stant had an excellent reputation right up to that point.

Deposits on the overflow bottle (and dipstick on F-Cars) are common with all kinds of coolants. There is commonly some machining oil and/or sealing additive in the coolant on new cars and eventually that stuff migrates to the overflow bottle leaving a scummy line on the inside of the bottle and on the stick. It is not harmful, it does nothing to the effectiveness of the cooling system.

As far as compatibility, there is some back-and-forth on that. GM does not approve of the use of DexCool in any vehicle that uses a copper/brass radiator or a copper/brass heater core. GM's concern is with the solder in those components and a process called "solder bloom" where chemicals leach out and deposit themselves on the solder joints of the copper/brass components.

Havoline, the maker of the orginal DexCool coolant says that it is fine with the solder in these components. And the only GM car made in the last 10 years with a copper/brass radiator was the pre 1995 Chevrolet Cavalier and Pontiac Sunbird. None of us own those and if we do we probably aren't going to put new coolant in them unless a hose pops."

One former GM tech that I work with says the LIM leaks started when GM switched to using plastic gaskets instead of paper. The paper gaskets cause pitting on the surfaces which they were mated to so that's why GM changed them.

Panacea
03-08-2005, 03:22 PM
The reason the gaskets fail on the 3400 is due to POOR ENGINE DESIGN!!!! That is the final answer. No if's, and's, or but's about it. That's the end of the story. DexCool has NOTHING to do with it.

Mike Jung
03-08-2005, 05:34 PM
...When we do this job and flush the system, what should we put in? Green or Orange?
Zerex G-05 engine coolant.

The colour is not important; as it is just a dye in it, but the type is.
As there are some similar coloured engine coolants, but are different types.
& there are different colour engine coolants for different auto manufacturers, but are the same type.

Even GM is going to stop using Dexcool from Texaco/Havoline in the future.

Breadfan
03-08-2005, 08:40 PM
Thanks guys, this has been a very informative thread thusfar. Lots of facts, no opinions or conjecture, that's definitely a good thing. :)

I'm learning a lot. I was pretty sure Dexcool wasn't the culprit, but honestly after hearing both sides I wasn't sure what to believe. Figured after another gasket leaking coolant it was time to find the answer.

Panacea
03-09-2005, 01:52 AM
Zerex G-05 engine coolant.

The colour is not important; as it is just a dye in it, but the type is.
As there are some similar coloured engine coolants, but are different types.
& there are different colour engine coolants for different auto manufacturers, but are the same type.

Even GM is going to stop using Dexcool from Texaco/Havoline in the future.

How come?

Malaclypse
03-09-2005, 01:42 PM
Oh, this reminds me.. The coolant that comes in the Aveo is blue IIRC. I saw one on the lot and found out that nifty little fact. Along with the power steering system using ATF and the transmission using something else entirely.

Goofy little foreign cross-bred cars.

Mike Jung
03-10-2005, 09:50 PM
...When we do this job and flush the system, what should we put in? Green or Orange?



Zerex G-05 engine coolant.

The colour is not important; as it is just a dye in it, but the type is.
As there are some similar coloured engine coolants, but are different types.
& there are different colour engine coolants for different auto manufacturers, but are the same type.

Even GM is going to stop using Dexcool from Texaco/Havoline in the future.



How come?

I read on another forum:
That Valvoline has/is going to get the contract to supply GM with their Zerex 'G-05' type engine coolant.
& GM was not going to use DexCool any more in the future.

GM was (maybe-?) not satisfied with the performance of DexCool engine coolant from Texaco/Havoline.

Ford (& assumed Daimler-Chrysler & other Asian auto makers) also has found DexCool type coolants not to be good on their gaskets.
DexCool was used before in Ford's Mercury Cougar.

Honda was kinda of freaking-out (& does not like DexCool type engine coolants) that GM was using DexCool in their Honda 3.5L V6-engines in the Saturn Vue's.

For more info on G-05 engine coolant, see: Engine Coolant/Anti-Freeze: Zerex G-05 ? (http://www.grandamgt.com/forum/showthread.php?t=40721)

G-05 type engine coolant has been used by Mercedes for like over 20-years; so it is a proven engine coolant.
Currently it is used by auto manufactures from the factory as OEM by:
Ford & Daimler-Chrysler (but with different colour dyes)

Zerex G-05 engine coolant by Valvoline (http://www.valvoline.com/pages/products/product_detail.asp?product=10)