Has any one come across a problem like this? My 98 1.8T start to run warmer and warmer until it eventually started to over heat. I have changed the radiator and thermostat twice. I have also checked for a blown head gasket. It still over heats, but when I remove the thermostat it runs fine except the heater blows clod even when the car is at operation temperature. When the thermostat is in the upper hose is hot and the lower is cold. I have boiled water to see if the thermostat is opening. It starts to open around 195.Any ideas?

 

Have you bled the air out of the system?

 

water pump?

 

Coolant temp sensor?

 

how about a heater core problem?

 

Yes I did bleed the system. I also checked the heater core for good flow. The only thing I have not replaced is the water pump.

 

I'm a little confused by the thread.

If it runs fine without the thermostat then you have a problem with the thermostat. If you have replaced it and checked the opening temperature, are you sure that you are not inserting the thermostat backwards in the car?


Otherwise, if you are sure that you are installing it correctly, it sounds like a waterpump problem.

 

is the coolant fan cutting in??