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Dexcool and nylon/silicone lower intake manifold gasket

Old  April 27th, 2008, 7:35 PM
Dexcool and nylon/silicone lower intake manifold gasket

"I have a 2002 Chevy Impala 3.4L V6. I use Dexcool antifreeze which there is a lawsuit right now because it eats away the original nylon intake gaskets and causes leaks & other problems. I have like a brown sludge in my radiator which I believe is oil as I have to add oil every couple weeks. If I have the gaskets changed and flush and replace the antifreeze with another, should that cure my problem ??"

Old  April 27th, 2008, 7:54 PM
RE: Dexcool and nylon/silicone lower intake manifold gasket

I have read in posts here that Dexcool has caused leaks at the gaskets, but my 2004 Impala just was in the shop to replace a leaking waterpump and the technician said there was no problem with my gaskets (thank goodness). The problem they said with Dexcool is that it most likely needs to be replaced earlier than the 5 years it claims to protect. The shop claims that the older this fluid gets the more acidic it becomes, being corrosive to the gaskets. I can't say one way or the other, this is what my shop says. So they maintain it is best to replace the Dexcool at maybe 3 years or so. I just changed mine after 4 years to prevent an issue, if there really is one. Also, changing those gaskets is very expensive I hear, so I wouldn't personally do it unless a leak actually occurrs.

I had that brown sludge as well in my expansion tank (recovery tank) for the antifreeze. The shop people have seen this too in other cars. But they didn't talk about it being an oil leak issue, just old antifreeze. Your having to add oil everyother week seems more like an oil leak, and a pretty good one somewhere. I checked my car after buying it and found once that the oil filter was just about to come off the engine ! So check that and of course the oil plug. Put some newspaper under the engine and maybe you will see a drip after running the car sometime.

Old  April 27th, 2008, 8:15 PM
RE: Dexcool and nylon/silicone lower intake manifold gasket

thanks stickershock , just trying to figure the best way to go as you get so many answers. Just wondering if you HAVE to use Dexcool only

Old  April 27th, 2008, 8:52 PM
RE: Dexcool and nylon/silicone lower intake manifold gasket

well this is all just funny. just lst summer i changed my 1998 silverado's coolant and i believe it was prestone green stuff and i used dexcool. sure enough i had a leak an thought it was my head gasket and almost had a panic attack... luckily(i guess) it was a minor lower intake gasket leak. i put some stop leak in it an its kept its ground still. but now that i hear all this stuff about dexcool and the orange fluid eatin the gaskets, im going to call dexcool and see if i can get them to pay for my new gasket... because i dont think anyone that uses GM recommended stuff should pay for it. my truck has 85000 miles on it, the coolant has roughly 6000 miles on it. havnt seen any sludge or weird floaties in my radiator and i keep a close eye on it since the little leak. i monitor everything after a bit of a long driving day. people think im just **** lol. if you can keep me posted about this lawsuit. ill jump on the bandwagon.

Old  April 27th, 2008, 9:03 PM
  • CF Monarch
    Join Date: Jul 2007
    Posts: 6,151
    Princeton, NC, USA
RE: Dexcool and nylon/silicone lower intake manifold gasket

Dex-cool hasn't caused the problems. its just the faulty material the gaskets were made of.

The reason you have problems is because you mixed the Dexcool with Green coolant, and it says on the bottle "do not mix Dex-Cool with any other color Antifreeze/Coolant"
Dex-cool and green = powerful alkaline
powerful alkaline= eating away at gaskets

The floating stuff and gunk that builds up around the radiator cap is just ionization. It can be avoided by maintaining a 60/40 balance of Coolant/water.

Old  April 27th, 2008, 9:09 PM
RE: Dexcool and nylon/silicone lower intake manifold gasket

Here is the dexcool lawsuit site


Old  April 27th, 2008, 9:10 PM
RE: Dexcool and nylon/silicone lower intake manifold gasket

well dont get me wrong... when i flushed my system i mean i flushed it... there was no more green or hardly any green in my system. i dont have any floaties like some people have said. my coolant level is at around a 55/45 ratio since i know the body shop drained my radiator and stuff and put it back and yea... but yea i have also heard GM decided to make profit not quaility when they switched the gaskets... if i had the money and place to do it... id rebuild my engine slap some comp cam rockers and put on some felpro gaskets. nylon...sheesh.

Old  April 28th, 2008, 2:59 PM
  • Super Moderator
    Professional Mechanic
    Join Date: Jan 2008
    Posts: 2,571
RE: Dexcool and nylon/silicone lower intake manifold gasket

Another problem to this issue is the aluminum heads that car makers are using to reduce weight. As a liquid passes over 2 dissimilar metals, voltage is produced, raising the alkaline in the coolant. A cool way to check if your coolant contains too much alkaline is to use a multimeter, put the negative lead on the ground of the battery, and put the positive lead into the coolant. If your coolant has been in there a while, you will usually get a reading.

Just did a quick google search, and found that someone has come up with a brilliant idea to moniter the coolants alkaline levels....

Coolant service monitoring system [/align]Publication Date:[/align]02/17/2005 [/align]
Document Type and Number:[/align]United States Patent 20050034510 [/align]Kind Code:[/align]A1 [/align][/align]
Abstract:[/align]Engine coolant and its related components is a vital fluid in any internal combustion engine, however it is one of the most neglected systems in the vehicle. The newest domestic automobiles do not have service indicators for engine coolant; which would allow the owner to service the fluid before any serious damage occurs from electrolysis and metal breakdown. The proposed Coolant Service Monitoring System (CSMS) will utilize sensors to monitor the pH of the coolant mixture, as well as the DC voltage of the coolant with respect to ground. By monitoring the pH and voltage, the sensors can notify the operator when unsafe coolant conditions are present. Ultimately, by preventing excessive corrosion and accelerated electrolysis, automobile owners can save hundreds if not thousands of dollars by not having to replace heater cores, expensive radiators, and water pumps with the CSMS implemented in the vehicle. [/align][/align]

Old  April 28th, 2008, 4:11 PM
RE: Dexcool and nylon/silicone lower intake manifold gasket


A person doesn't HAVE to use Dexcool, but get it all out of the car first. A shop of mine went back to the old green stuff on folks car unless the owner said don't.

I went to Walmart to pick some of the old antifreeze (2 year)up, but mine only sells the 5 year anitfreeze. So I bought that and backflushed the old out and poured in the new.

Old  May 3rd, 2008, 12:57 AM
  • Senior Member
    Join Date: Jan 2008
    Posts: 371
RE: Dexcool and nylon/silicone lower intake manifold gasket

Ok so according to the website it only applies to certain vehicles with defective gaskets:
Impala, Lumina, Malibu, Monte Carlo, Venture, Corsica, Beretta, Lumina APV
So it is like Euro said particular gaskets not the fluid I think? Am I right?
Has anyone used the prestone that they say goes with any color coolant?

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