Bleeding coolant system.....?

[TeeJay3800]

This morning I replaced my thermostat. After it was done I took the radiator cap off and started the car. After it reached operating temp I was only able to add a small amount of coolant (makes sense since only a small amount came out when I replaced the t-stat). Later, when I drove it to school, the low coolant light was going on and off every 2 minutes or so. I opened the hood at school and there are no leaks and the resevoir is full. This means I have air in the system, correct? How do I remove the air in the system?

[GutlessSupreme]

open the bleeder valves on top of the t-stat housing and you might have one over on the heater by-pass hose next to the pass. side motor mount, but I've seen a few cars without them so maybe you don't have one.. be very gentle, they're made of brass and twist off very easily. I think you just let the engine run for a minute until coolant comes out of both and close them up quick while it's still running.

[TeeJay3800]

Can I open the bleed screw while the engine is already hot? (like if the car has just been driven)

[Robby1870]

Can I open the bleed screw while the engine is already hot? (like if the car has just been driven)

Yes, you can, but the car needs to running while you do it, but get ready to get your hand outta there after you open it, and be ready to close it as soon as air stops coming out. It would be better to let the engine cool a little and leave the bleeder screw open as the car warms up, then close it after the T-stat opens, letting the air out.

[THe_DeTAiL3R]

Yeah just slowly open it when the engine is running and warm. You might have lost more coolant than you thought when changing the t-stat.. when I did mine last I lost more than I thought I did... mysterious.

[Regal_GS_1989]

Damn!! All i can say is that if you ran the car for more than ten minutes with air in the cooling system, You probably cracked the heads. The same thing happened with my 89 regal GS. when you bleed the system, be sure to check the coolant reservoir for any air bubbles. If you get air bubbles, get ready to tear open that motor.

[TeeJay3800]

I have no idea how air in the system could crack a head....that is bizzare. Any ways, the coolant light stopped coming on, so I never bothered to bleed the system at all. When I replaced the water pump this summer, all I did was refill the coolant and thats all. No bleeding of the system and no problems so far. Should I be concerned about air in my system causing a problem?

[Regal_GS_1989]

It can crack the heads by bulding up an extreme amount of pressure and heat. If there is any air in the cooling system, the top of the heads will not get cooled down. They can reach upwards of 500 F. Thats what happened to the heads on my car, got an air pocked with out knowing it. Adn seeing how the coolant temp sensor is right at the top of the head, your temp gauge or warning light won't show that it is running hot.

[TeeJay3800]

It can crack the heads by bulding up an extreme amount of pressure and heat. If there is any air in the cooling system, the top of the heads will not get cooled down. They can reach upwards of 500 F. Thats what happened to the heads on my car, got an air pocked with out knowing it. Adn seeing how the coolant temp sensor is right at the top of the head, your temp gauge or warning light won't show that it is running hot.

Interesing theory. Now you have me all concerned. However, I replaced my water pump this summer without bleeding the system at all (only refilled the resevoir). I drove it 2300 miles from CA to MI without any problems...... Maybe I'll try the bleed screw idea.