I need help. i have a 1990 maxima. the thing started overheating and after changing the thermostat, and flushing the radiator inside and out, it quit overheating. problem one solved. problem two, the heater will not blow hot air. according to the wife, this has been happening even before it was overheating. ive had the heater core flushed through both directions and have the heater control valve bypassed. still no luck. now to add insult to injury, it has overheated again twice in the past 2 weeks. there is no oil in the water and no water in the oil. anyother suggestions?????

 

is it losing water somewhere, somehow? When's the last time you had your water pump replaced?

 

i have never replaced the water pump and no its not using any water. when i replaced the thermostat, i also replaced all 3 drive belts. at that time i checked the play in the water pump and everything felt fine.

 

There may be a problem with the controls for the heater core, there are actuators that control doors that open and close routing the air.

 

Sounds like an air pocket. That or a blockage right before your heater core. When I picked mine up, it had no heat. Filled the radiator and viola, heat so hot I have to turn off the fan and switch it over to the cool side. This is in 20ish degree weather also.