My 2001 started to overheat so i changed the thermostat, new radiator cap, and bled the system. It kept overheating so i took the themostat out to see if that was the problem. Without the t-stat the car warms up to normal operating temperature. I thought the temp was supposed to stay cool without t-stat. So i drove it for a while and it stays at normal and then after awhile slowly drops between cold and normal and goes back to normal when i use a/c. I changed the oil and it was normal not milky and the exhaust is not blowing white smoke so i dont think its the heads. It runs at normal temp without t-stat but starts to overheat when i put a new one in. And when i parked and turned the car off i heard hissing like air escaping somewhere and saw liquid squirtin out the firewall, not a lot though. Also the overflow reservoir looks like coolant splashed out the cap. Could i have a bad radiator? Also the metal tube above the water pump that looks like its sticking out halfway looks like coolant was leaking out of there too. Any suggestions or ideas would be appreciated.

 

sounds like you water pump is starting to fail.

 

You saw "squirting" coming from the firewall? Was it near the top where the heater hoses connect or about a foot down from that? If it was near the top, then you have a leaking heater hose or you have a leaking heater core.