My guess is the head gasket, have same problem. Nightmare
water pump
you might want to check for a blown head gasket or a cracked head or block. espically if it loosing water out of the radiator with out leaking on the ground.
had the same problem with a sibring,took to the garage,they replaced the thermostat and gasket and found a hairline crack in the thermostat housing they replaced the housing and everything was fine then
check your radiator. is it clean or does it need to be replaced? a simple cleaning cured my problem.
If your radiator isnt leaking and car is having a over heating problem and coolant spewing out. Chances are your thermostat needs replaced. possible the radiator needs to be flushed. But more likley its thermostat
You may have the problem of your intake manifold gaskets. They are a problems on the lumina. I had to have mine replaced due to the same thing. Also check if your coolant is mixing with your oil if it is. Than it is definitally your intake manifold gasket.
dose the electric fan run if not check the relay if it runs check the water pump
Check the coolant fan see if it turns on when the engine gets hot. if not then your temp sensor could be bad
Try taking the thermostat out completely, then see if it still overheats. If so, your only other problem has to be a bubble in the system and it needs to be burped. Took me about an hour to get a stubborn air bubble out!
if the pump and thermostat have been replaced on a 2001 malibu and it overheats and the heat doesnt work now but the air does. do it need bleeding still , will air in the line still cause that problem...
Take your thermostat out and put everything back together, run your car without a thermostat... If your car no longer overheats, replace your thermostat.
I don't know how old this question is, but we had a similar problem, it turned out a head gasket was leaking. We've had it replaced and the van has been driven about 500 miles since then without overheating. I'm sure that's not what you wanted to hear, but I would find out if that's the case with yours too.