Brown/Carmel Gel in radiator - lower intakes to blame?

[snofly3]

I've been getting mixed feedback on this. There is a thick brown gel in the radiator of a 3400. It clings to the walls of the radiator and has backflushed into the resivour. The dexcool level was low in the radiator. The oil seems to be free of coolant.
I have heard that this is simply the breakdown of the dexcool when air is introduced into the system.
I have also heard that this gel is the result of oil getting into the coolant through the lower intake gaskets. I question this theory because the lower intakes don't have any pressureized oil passages in them. They do seal oil, but it's only splash. I don't see how this could introduce oil into a cooling system that pressurizes at 16psi. The only other way I can see oil getting into the cooling system is through the oil cooler lines.

If anyone knows about this gel, it would be very helpful. Thanks for your time.

-Aaron

Firestone Service Center Technician
Waubonsee Community College Automotive Technology Student

[tractorman]

The wife's '94 corsica had that same sludge in the cooling system when I first met her and the car 6 years ago. At the time I thought it was stopleak, but now I think somebody mixed red stuff with green stuff- only a guess though. I flushed the cooling system as well as I could, but plenty of the crud remained. The car had moderate overheating problems for a couple years. I finally pulled the radiator, sent it to a shop, had it rodded and cleaned out, and the hot side gasket replaced. I also removed the thermostat and flushed the engine and coolant tank with a steam cleaner. Put it all back together and filled it with green John Deere antifreeze. It's cooled great ever since.

Doesn't matter so much why the crud is in there- it's gotta be cleaned out or you'll have problems. I've only ever seen this sort of sludge in cooling systems with that dexcool crap- I won't use the stuff, myself.

[willbird]

Wifes 95 grand prix had it, only had dexcool in it up to that point, no oil leaks into coolant that I know of, or vicey versa, my vote is Dexcool boogers....we flushed, and flushed, and filled with john deer green, no boogers since.

Bill

[Rhedalert]

at around 50k miles, my sister's '02 GP SE had that "gel". Someone that worked at GM mentioned it is a sealant used in the cooling system, due to the crappy reliability of the intake gaskets. Over time the sealant collects, especially at the filler neck.

[willbird]

I was thinking about this today, and came up with another angle. Where I work we machine I4 and I5 blocks and heads, these are impreg with a resin...these are lost foam castings. I can't say if GM impregs other alum parts for other engines, but I'm betting they do, could it be that the impreg resin reacts with the Dexcool ??


Bill