Yes you can bleed the cooling system at home; I suggest you put your car on ramps or jack stands first.
Open your radiator cap, loosen up the two bleed screws on the cooling system: one is on top of the water pump, the other is at the thermostat housing.
Turn on the car and let it idle; turn on your heat. When coolant starts gushing out of the bleed screws, tighten them. Squeeze your upper radiator hose to let the air out of it.
Add coolant in your radiator as level goes down. When coolant starts boiling over your radiator, put the cap back on.
Also, make sure your level in the overflow tank is a little above the cold mark with engine cold; if your level is too low in there, your engine will suck air into the system when it cools down.
Since you're at it, I would replace the thermostat like you suggested, especially if you never replaced it before. The symptoms you describe sound like a defective thermostat to me. It's not too complicated and it's cheap.
To know for sure if you have a leak, pressure test your cooling system, including your radiator cap.
Hope this help.
Wednesday, December 10th, 2008 AT 8:39 AM