Brown Sludge under radiator cap

hey there everyone. i have an 04 Comp G and i noticed a big amount of brown sludge under the radiator cap AND in the resevoir. any idea of what could be causing this? i guess i need to flush it?

thanks!

YUP that would be Dex-cool my good sir, I would suggest flushing dex-cool out. Then putting the green stuff in and driving for awhile flush and redo. Took me like 3 times

every one has thier beliefs on Dex-cool. I personally have seen what it has done to my '02 GP. about $400.00 worth of damage, thats if you rebuild the top half of the motor your self! GO-GREEN!!!!!!! Dex-cool eats intake gaskets, Head Gaskets, PLEASE FOR THE LOVE OF GOD DON'T WAIT !!!!!!
seriously thoughGM designed dex-cool to maintenance free for 100,000 miles -and it is.
it also is hard on other stuff inyour engine
good luck flush,flush,flush!!!!!!!!!!!!!!!!!!!!

Sounds like your intake gasket allowing oil into your coolant. and coolant into your oil. An ethylene glycol test to your engine oil will confirm coolant contamination.

Good news is, its a super easy job and now Fel-Pro FINALLY made theyre famous upgraded intake manifold gaskets (permatorque) for the 3800. been using those gaskets on the 3.1 and 3.4 for years and its a permanent fix that doesent break down like the replacement plastic gaskets do.

thank you for the replies! the oil looks fine all of the time so i dont think any coolant is getting in there. this dex-cool stuff is nasty. i like to do everything myself, but i may have to take it somewhere to get a flush or two done. i do have a feeling, like you all said, that it will take a few times to clear out!

Originally Posted by scbird94

Sounds like your intake gasket allowing oil into your coolant. and coolant into your oil. An ethylene glycol test to your engine oil will confirm coolant contamination.

Good news is, its a super easy job and now Fel-Pro FINALLY made theyre famous upgraded intake manifold gaskets (permatorque) for the 3800. been using those gaskets on the 3.1 and 3.4 for years and its a permanent fix that doesent break down like the replacement plastic gaskets do.

GM has actually updated the plastic gaskets as well now

Brown sludge on the cap? That's not necessarily oil. Dexcool does look "brownish" when it starts to sludge up.

But I agree, switch to the green stuff.... I will be this season.

my bro works for a classic car and custom ac shop, they always recommend going away from dexcool.....my 98 mustang and 98 gtp have had intake gaskets replaced....change,before it's too late!!!!!!!!!!!

had brownish sludge under radiator cap only noticed it while changing out water pump,(went out 2 weeks after i bought the car ) i thought it might be radiator stop leak the dealer put in before they sold me the car

thank you for the replies!

has anyone done the flush themselves? is it a difficult task?

It is dex cool. Period. Not oil.

Do not flush it yourself get it flushed by a pro with the machine (midas for instance). You should go back a month later to get it flushed again to get all of the circulating jelly out

So I noticed the brown sludge crap under my radiator cap also, had the system flushed a couple of weeks ago and installed a new thermostat......I guess I'm wondering if or how long it takes for the gaskets to go bad with dexcool.....I have heard or read that since the radiators are aluminum the "Green" antifreeze will eat aluminum thats why the dexcool is used....Who Knows for sure?
My car is a 2003 GTP did GM use good gaskets on this car?
I have almost 102,000 miles and I dont think coolant is leaking into the oil but I don't need that problem.
What do you guys think?

Originally Posted by Freebeer187

It is dex cool. Period. Not oil.

Do not flush it yourself get it flushed by a pro with the machine (midas for instance). You should go back a month later to get it flushed again to get all of the circulating jelly out

Mmmm, circulating jelly.


I will try the flushing thing as well with my car. Can't hurt any...