Driving home last night after about a 20 mile drive, i noticed the heater had started blowing cool air. (it was set for 80+ degrees)
Within the next 1/2 mile or so the info center tells me that the coolant is hot, followed by ac is shutting off, followed by engine is overheating--idle engine, followed by shut off engine.
I checked and the coolant temp had gone from its normal 200 degrees or so to 255. Stopped at a nearby store for some coolant and some engine cool down time.
Added aprox. 3/4 of a gallon of coolant and drove the 4 or 5 miles home with no trouble and steady coolant temp.
On my way to work this am, I made it about 20 miles (almost made it) and the same thing happened, in the same order.
This time I also noticed the info center telling me to change my oil. (I had it changed aprox. 1.5 mths ago)
Checked the oil level--it looked like it could use a quart, nothing unusual there. The coolant level seems ok also, no leaks that I can see.
Before the car overheats the heater is working fine. The car doesn't seem to be running rough or anything, just the info center setting off alerts. Before it overheated today, the service engine light also came on. Any ideas??
what happened last night when your heater stopped working was the low coolant. your heater works by the heater core, which is nothing more than a small radiator.
what happened this morning when it stopped working(presuming that your coolant level was still good) was that the cooling system "hydro-locked". what this means, is that something happened....more then likely an air pocket formed in the cooling system......that prevented the coolant from flowing properly.
the a/c shutting down is normal. the gm computers are programed to shut it off when coolant temp reaches a certain point...i think it's 240F. your radiator fans should've been running on high at that point too.
check simple things first. the overheat happened when you were driving, not sitting in traffic, correct? if sitting in traffic, check cooling fans first. if it happened when you were driving, then check thermostat first. check water pump second.
making a BIG leap here....but if i recall from the last time you posted, you have the 4.9L v8, right? how many miles? these engines are common to lose head gaskets, which if it pushes pressure into the cooling system, it will hydro-lock it.
don't worry about the oil change notice being part of this problem. they go by key cycles and/or mileage driven. even if you did it a month and a half ago, you may need it again. i have a few fleet cars that go with 5,000 intervals, rather than 3,000 intervals....and i'm doing their cars every month.
if you have more questions post em, or pm me, and i'll do what i can to help ya.
