2000 Grand Am 3400 - bleeding cooland system??

[Old Chevy Lover]

recently replaced the intake gasket, no more leaks! But, something still isn't right and I can't pinpoint the problem. maybe air trapped in the cooland system or something? The air coming out of the vents is cycling, and sometimes the therm doesn't want to open at all. When that happens, then there is no heat at all. But, if I unscrew the cap on the coolant tank and slowly let out the air (not supposed to have any air at all, right?) then it will give a big gurp/gurgle, and seem to be fine for a little while. Shouldn't there be some heat there regardless of the therm being open or closed? Maybe there is a way to bleed the coolant system that I don't know about to get all the air out?? HELP!

[xeroinfinity]

hey Old Chevy Lover. yes the air does get traped in the heater area. If you let it run with the cap off the resivour and keep adding coolant when it gulps down some. Also turn the heater on full blast, this will speed up the prosess. It might take awhile(30min+) to clear the air, but that is what causes the heat to cycle hot-cold. they put a bleeder by the front valve cover by the water pump, its brass, but its messy and a pain to get to work. your supposed to be able to hook a hose up to it and drain it back to the resivour so you dont waste/contaminate everthing with coolant.

[Old Chevy Lover]

that makes sense. I've just tried to top off the tank, then put the cap back on, let it get hot, cool off, take the cap back off. But, after reading your info, I'm just re-circulating the trapped air. Would this also be enough to cause the cooling system not to circulated coolant at all (causing the intermittent overheating issue)?

[eprince]

when the air bubble gets to where the temp sensor is . It will get hot and register that is overheating. as soon as the bubble burps the temp drops. I have had to add coolent for a couple of days till all the air was out. Just keep an eye on the level

[xeroinfinity]

yes it will over heat and will cause it not to flow properly. Its worth letting it run and keep adding as needed.

[Old Chevy Lover]

I let it run about 45 minutes yesterday, adding coolant as it would bubble or push it out. Got to where the temp gauge was steady, the heater was putting out constant hot heat, and the tank was full. I figured that was good enough as it wasn't bubbling anymore. So then I drove it for about 40 minutes. Everything was fine,the way it should be. Shut it off, let it cool off, checked the coolant level, but the coolant tank was empty... It looked like it had been pushed out of the overflow So, this morning I drove it to work, and sure enough, it is back to spuratic heat and trying to get warm. Any suggestions???? Could there be a head gasket problem causing the cooling system to 'pressurize' pushing the coolant out?? I've always heard of cooland getting into the oil or into the cylinder... What else could it be?

[Old Chevy Lover]

Also, I did fill the coolant tank back up once I found it was empty.

[xeroinfinity]

sometimes it takes a while to get all the air out. I hav had issues with the low coolant myself, and it is a pain. The resivour will push out alot of coolant if the tank gets to full, and seems to keep flowing until its empty. I've spent two hours on a 2000 Grand Prix getting the air out monday, I was ready to shoot the damn thing.

There is a air bleeder on the black hard lines that run on the engine top, on the passanger side right above the water pump. Its just a couple brass fittings, the smaller one is the bleeder. It is hollow in side and has a hole through the top to purge some air out. if its still cycling the heat try running it some more and slowly open the bleeder a little, some coolant may start flowing out, just close it then let it run abit and then open the bleeder. They do suggest putting a hose of some sort on the bleeder and puting it in the resivour so you dont waste coolant or spill it all over the ground.

Head gaskets arent something that the 3.4's usually blow, but its possible, and this can be checked by testing the compression of the cylinder. Its usually the lower intake gaskets and it can leak into the cyclinders and get burnt off. You really wont notice anything running out the tail pipe like I've heard others say. Sometimes it does go into the oil, but if its not a bad leak you may not see water in the oil. But if you get the heaters air pocket out and you're still looseing coolant it probley is time for the intake gaskets to be placed and thats a pretty big expessive job.

[Old Chevy Lover]

I just replaced the intake gaskets (had another thread that you replied to last week). Turned out the job itself wasn't too bad, just really intimidating when looking at all the wires, lines, etc etc etc. Coolant is no longer leaking 'outside' the motor that I can tell.

[xeroinfinity]

Originally Posted by Old Chevy Lover

I just replaced the intake gaskets (had another thread that you replied to last week). Turned out the job itself wasn't too bad, just really intimidating when looking at all the wires, lines, etc etc etc. Coolant is no longer leaking 'outside' the motor that I can tell.

Thats kick ass! The job does look harder than it is. There are a "few" things to disconnect. LOL! I do answer alot of posts, sometimes I forget and repeat myself. I just try not to spread myself to thin and help who I can. No leaks is a good thing. With most GAs blowing these gaskets all the time, they(GM) should've done something. I think its because the blocks steal, the heads and intakes are aluminum. So the alum. heats up two or three times as fast as the block causeing stuff to move around from heating and cooling and eventually starts leaking. I had a Corvair with the flat 4, it dont the same thing with gaskets, but it would leak/blow oil every where. sorrie just rambling...

[rkuchar1111]

I am having the same problem. I am what you would consider is a newbie. I want to check the thermostat to see if it is defective. But I do not know where it is located on the engine. Also where is the bleeder on the engine. Since I want to ensure that there is no air in my engine.

[xeroinfinity]

if u read above rkuchar1111 i believe i explained where the bleedr is. The thermostat is below the throtle body(air intake) in between the exhaust crossover and the block.