Sludge on my radiator cap!

[kahnaguy]

I just had my oil changed and saw some sludge on my radiator cap. Was told this could be a head gasket problem. But no sludge on my oil dip stick and no white smoke coming out of my exhaust. I have a 97 Chev Lumina LTZ with a 3.1 engine. Am wondering if i should indeed install a new head gasket?

[Schurkey]

When was the last time the coolant was flushed?

You can pretty much expect to see crap in the cooling system if the coolant is ancient.

That's not to say you "can't" have a head gasket leak, or a crack in a casting, or whatever. It's just that I wouldn't panic about it unless you know for a fact that the cooling system has been maintained to factory specs. If not, (and that's extremely likely) I'd be looking at ways to properly and completely clean it and see if the sludge returns.

[kahnaguy]

Originally Posted by Schurkey

When was the last time the coolant was flushed?

You can pretty much expect to see crap in the cooling system if the coolant is ancient.

That's not to say you "can't" have a head gasket leak, or a crack in a casting, or whatever. It's just that I wouldn't panic about it unless you know for a fact that the cooling system has been maintained to factory specs. If not, (and that's extremely likely) I'd be looking at ways to properly and completely clean it and see if the sludge returns.

It was flushed in summer of 2004 and will get that cleaned up right away and see what happens. Thanx for your reply.

[richtazz]

Keep an eye on your coolant level, as your engine is famous for developing intake leaks.

[northwichita]

I'd go with deposits from the Dexcool antifreeze. The stuff breaks down and coats the cooling system, and it tough to clean out quickly. I just bought a 97 lumina with the 3.1, had the nastiest looking overflow. I found from a previous vehicle to just flush with water , run it, repeat, until it stays clean. And I won't use Dexcool. Do a web search on that nasty stuff, it's probably fine on a short term basis, but the average person doesn't change it and then-- .

[93LT]

My overflow tank was terribly dirty and the cap was slugged as well. I flushed the system, cleaned the reservoir using castrol super clean and a wheel cleaning brush, the sludge wouldn’t budge with just castrol super clean alone. Oddly enough, I removed the radiator hoses and all openings were spotless, also the antifreeze coming out was clean.

After the flush and cleaning of the cap and reservoir, the system has remained cleaned.

[cadgear]

Originally Posted by northwichita

I'd go with deposits from the Dexcool antifreeze. The stuff breaks down and coats the cooling system, and it tough to clean out quickly.

Technically its not just DexCool. Any coolant that's old will give you sludgy residue in the system. My neighbor's Cutlass has a fairly clear overflow, except for the green caked-on sludge from the green stuff.

As for the original poster, its just buildup. 9 times out of 10 the intake leak will give you coolant into the oil. A head leak will give you oil and/or combustion gases into the coolant, though at the mileage I doubt it. Only way to be sure is a cooling system pressure test and/or cylinder compression test.

I wouldn't sweat it, though.