02 cavalier coolant leak expansion tank

[Scottm69s]

I have a 02 cavalier 2.2 it just started leAking coolant when in a drive thru. Steam started coming up from hood. When I looked under the hood the expansion tank was hissing and it looked like the antifreeze was coming out of the overflow tube at the top of the tank. What should I do? It is sitting still at the parking lot

[gmtech1]

Need to verify cooling fan operation and make sure the cap is good. If those things check out you could have a stuck thermostat, bad water pump or possible headgasket problem.

[danielsatur]

1) Turn the heater on high max with engine idle.

Are you getting any heat?

If yes, monitor temp gauge till temp go's down.
If No, turn engine off & let it cool down.

If no heat, there's a shortage of coolant because of a boil over or leakage
in the coolant system.

What caused the boil over?
bad coolant fans, fan relay/fuse, thermostat, plugged radiator core, or leakage in the coolant system.

Note - If your able to turn the HVAC on high max cool, both coolant fans should turn on.

[Scottm69s]

ok, I had the car checked out by a mechanic and they could not find any problems with it. I took it home and let it cool down. This morning I filled it up with coolant, warmed it up and drove around a while. Nothing happened, all the coolant is still in it and no hissing sounds around the expansion tank. The cooling fan works fine. Before the engine would always go 2 lines over 195, the fan would kick on and bring the temp back down to 195. From my test drive and letting it idle for a while I couldn't get it to go over 195. The heat works great and the fan kicked right on when I turned it on and kept the temp down. I did notice that when I parked it the A/C line was sweating a lot and dripped a lot, but I didn't run the a/c at all. The thermostat was changed about 2 months ago and the car was driven from MI to FL. Any ideas what is going on?