overheating problem

[skeeter123]

A quick check to see if its a heat-problem vs. head-gasket problem: when engine's cold, squeeze the radiator hose; should be easy to squeeze. Start engine; squeeze hose some more.. If pressure builds rapidly in hose (within a minute or two), it's pressure leaking in from the cumbustion chamber. If it takes 7-10-15 minutes to build up, (and levels off at 7-10 psi), it's normal.
I know it's a PITA with the 3400 cooling system. I ended up draining out the coolant and flushing/bleeding several times, and re-using the coolant since it was getting expensive. When you had the heads off, did it look pretty clean inside, or all gunked up?
I'd flush the bejeezus out the system, with heater on full;
Also, the radiator could be clogged so that even a new pump can't circulate coolant properly. Have you used the drain plug in the bottom of the radiator to drain the coolant? Did it just flow right out, or was it clogged up. If the drain plug is clogged, it a sign that lots of debris can build up at the bottom of the radiator. You might want to flush the radiator itself; take off the top and bottom hoses and flush it out with a garden hose.

[uspres2020]

Is there a drain plug on this car? I never saw one. I have just been draining it from the radiator hose on the passenger side that is near the bottom. The system has been flushed and I am pretty sure pumping through the radiator isn't the issue although I have not back flushed with a garden hose which I did think about doing, I just never got around to it yet.

Right now I am shopping for G6's. They seem to be about the only reasonably priced used car on the market.

I got the Grand Am back into driving condition with my constant vent system and no thermostat. Good enough to get me to the auto dealers I guess. I will probably be trying the back flush in the near future and if that doesn't work I think I will be shopping for a used head. Thanks for all the help, I was surprised that it wasn't holding pressure before, and even more surprised when it wasn't my problem. This has probably been the most mysterious problem I have ever had with a car.

[skeeter123]

Like lots of things, it's a pain-in-the-a##. It's on the front, bottom, driver's side corner of the radiator; a good pic is at:

http://www.automotiveforums.com/vbul...tor+drain+plug

the picture shows an original plug; since they break a lot you may have an after-market one that is usually black with "butterfly wing" which you twist to open it up. As in the linked picture:
"To loosen the radiator drain all you need is a tool like in the pic below. This is a 1/4" drive socket handle. Insert into center square of drain plug and then just turn 1/8-1/4 turn counterclockwise. The drain plug does not need to be removed."

If you've got the butterfly-wing, you can twist it by hand. These plugs are easy to break. I broke mine and then replaced it with one from A-Zone. My radiator was so clogged up on the bottom that I was able to drive to the store without a plug; and take the old broken plug in to compare to the replacement. The plug works as a valve to open/close a passageway to let the coolant drain out the bottom of the radiator. If it's clogged, use something like a plastic ty-wrap to jam up in the passageway, hopefully that will unclog it. Even as I write this I'm starting to feel like strangling whoever designed it.

[3100]

Hi, you might want to check your exhaust system for clogging. Why? because clogged cat will not allow hot exhaust fumes to escape from engine on time and engine will heat up faster

[hinton08]

Did you try bleeding the air out of the system again? These vehicles are very hard to get all the air out of them. Leave the radiator cap off and let it run for 10-15 minutes and see if any bubbles appear (as long as it dont overheat severely while your waiting). Also, when you replaced the head gaskets, did you check/clean the cylinder heads or the block? You could have a cracked head or block.

[3100]

any updates? did you check exhaust for abnormal back pressure?

[zes57]

did you ever scan the dtc codes? replace reservoir tank with the cap? did you ever resolve this?