Overheating Problem

I have a 1994 Grand Prix with the 3.4 engine, 114K miles. It is just now getting cold here in Ohio, and I noticed on a couple of days ago that my car would not run much past 100 degrees, and there was very little heat coming from the heater. I decided to change the thermostat, and when I pulled the thermostat housing, I was surprised to see there was no thermostat in there! Now I've had this car for about 6-7 years, and this is the first I've noticed that I have no heat. I just had the Timing Belt replaced, as well as the Heater Core Pipe (runs from radiator to heater core), and I am thinking maybe the mechanic forgot to replace the thermostat. I think that I would have noticed this sometime during the last 7 years if it never had a thermostat since I bought it. Anyways, I installed a thermostat, and now the car is running very hot, at 210 degrees, and works its way all the way to 260 before I shut it off and let it cool down. I then decided to bleed the system, and this is what I did: Drive car until the temperature redlines (takes about 5 minutes), then with the engine still running, open the bleeder valve, and when I do this, there is a TON of air that escapes. I let all of the air escape until I get a steady stream of coolant only, then tighten the bleeder valve (sometimes it takes like 10-15 minutes for all the air to escape). About the time I get the steady stream of coolant, the engine returns to about 210 degrees. I then top off the coolant resovoir. Then I drive the car around the block a few times, and in about 5 minutes the temperature redlines again (260 degrees). I open the bleeder valve, and again, I get a TON of air escaping. I repeated this process for over 3 hours straight (no kidding) and this thing is still overheating. I must have bleed both of the bleeder valves like 15 times, and each time there is a TON of air that escapes, no kidding. How can there be so much air in the system? The heater core is also making a funny sound when it starts to get real hot, like a boiling sound, or maybe that is just the coolant boiling in the block, I'm not sure. I have noticed that both of the fans do kick on, but after I drive around the block and the temperature redlines, when I open the hood, both fans are not always running, even though the temp is like 260 dgrees. I thought about maybe changing the coolant temp. sensor, but I am not getting a SES light. If that was bad, wouldn't I get a SES light? If anyone can help me out, I'd sure appreciate it. THANKS!


Here is a little update. When I went out this morning to start the car, the coolant resovoir was empty. I filled it up, and started the car. Ran very rough at first, and the idle went up and down from 2-3K down to <1K and stalled a couple of times. I drove it around for less than 5 miles and it warmed up, then started to overheat, and I could smell coolant pretty strong while driving. Then it shot up to 260 degrees as I was pulling in my drive. I left car running, popped hood, and neither fan was working. Steam-like gas coming from exhaust manifold (?) Any body got any ideas?

Wow, bad luck man. From the sounds of it you have one of a few things wrong. You may either have a blown head gasket, a blown intake gasket, or a cracked block. Odds are its a blown head gasket. That would also explain the steam from the exhaust manifold area.

Thanks for the reply. I think you are right. I spoke with my uncle today, and he is a diesel mechanic, and he said the same thing. I'm thinking its a head gasket.

Does anybody know about how much that should cost to fix, and the basic process involved? If I am paying to have the head gasket done, should I also have the intake gaskets replaced at the same time? Any other maintenance items I should address while the thing is torn apart?

Thanks,

The intake gasket should be replaced as part of the head gasket replacement because the intake must be removed in order to access the heads. Just be sure to let the machanic know that you don't want any "recycled" gaskets.