My daughter has a 98 malibu, It keeps blowing out anti-freeze on her every 2 months or so. She drives it daily and it does not do it consistently. I have replace the belt, pump, thermostat, reservoir cap and have flushed the radiator. I do bleed it while I fill it up after it has an issue. Both fans run and show no problems.
The way it usually happens is, I check her fluids often and never have to add anitfreeze. She will be driving it and when she comes to a stop, the car blows a lot of anti-freeze out of the reservoir. She says the temp gauge stays around half way and nevers shows hot. I get it home and fill/bleed it and run with the a/c on for over a 30 mins and its fine.
Does anyone have an idea what it could be?
Thanks in advance.

 

needs head gasket replaced or she is driving in the wrong gear overheating the transmission.

 

If it was the head gasket, wouldn't it blow water out every time not just once every couple months of driving or so? And she drives the car in drive not second or first.

 

I'd suggest a partial plugage. Pull the radiator, (I know you've flushed it) flush the system again, and replace the thermostat.

 

Hello, My son's 99 Malibu also has an issue with overheating. The heads have been done as well as a new radiator, new thermostat, new hoses, and 2 new fans. I have heard tell of a bleeder valve on these cars. Could someone tell me where it is located please?

 

On the 98 3100 it is right above the water pump. There's a pipe that comes up out of the pump with a plug with a bleeder on it. Be careful when tightening it up cause it can snap easily.

 

Check radiator cap might not be able to hold pressure.