I just got a 1998 Lumina.. It started overheating and having low coolant problems literally a day after I bought it.
I'm thinking I might have blown a gasket somehow; GM'* gaskets in the 3100, and your 3800, are cheap. They used cheap gaskets in a lot of their engines, so a lot of them have the same problems. There are replacement gaskets available to fix the car with. And, to add to the fact that the gaskets suck, that DexCool that was in your system could have been old, and started corroding the gaskets and other parts of the engine. Apparently after it'* been used up way too much, the PH level changes and it becomes acidic? But anyway..
Here'* one way to check, even though it sounds like you already have some symptoms..
Check your oil, see if it'* milky or it has white spots in it, that'* coolant in the oil.
White smoke from exhaust, or engine bay
But yeah, I'd say take a look in your oil and see if there are any signs of coolant trying to mix in. That along with the smoke should be a sure sign of bad gaskets.
Also, there are little strips to test the coolant in your system to see if there'* exhaust in the coolant, which also can happen with a blown gasket.
Good luck, those gasket jobs are expensive. Not the parts, just the labor.
Also, if you can help it, DON'T run the car until you know there'* no coolant in the oil. It can cause engine bearing problems, which happened in my '96 SE, and I had low oil pressure problems ever since [but the car still ran fine]
Last edited by Brando_is_DTF; 06-10-2009 at 08:58 PM.