2000 ALero 6 cyl 108,000miles
Overheated in traffic: Could not make it to siding before it got
hot...very hot. Waited several times for it to cool then added fluid and
drove until i saw the arrow going up...got home.
Just to be sure, I replaced the water pump and the thermostat. Replaced
coolant making sure that the radiator was full and the reservoir was
topped up. Did this twice. Both times the car ran fine--no smoke that I
could tell, and the Engine runs strong--no sputtering etc. Dip stick does
not appear to have water in the oil, and the oil does not smell burned or
like antifreeze. It heated up but not into the hot red zone.
BUT!!!....within 10 minutes of operation the reservoir emptied out through
the overflow as far as I can tell. My brother seems to think that this is
not a head gasket problem, but may be a blockage or air lock somewhere,
perhaps in the heater core(I don;t get any heat. So when the engine heats
up it boils water out of the block.

Any suggestion of how I might trouble shoot this, or if you know what this
is likely to be? pdc
Thanks.