Been noticing lately that my heater stopped working and temp climbs to red. Came to find out that I had no coolant in engine.
Filled it up. Problem is.. it still happens.
Now, radiator full, Heater works fine, but if I drive it for a while, temp climbs and heater stops working. Took it in. Mechanic said coolant pump was leaking. replaced it, and temp sensor.
Here is how I can reproduce problem: Drive with high RPMs for about 15-20 minutes. I put it in Low 3, and got on the highway for about 10 minutes. This kept the RPM gauge up to about 4 or 5. temp gauge climbs rapidly once it decides to start.
I drove home after that point never letting the rpm gauge go higher than 1 and a half. (if I did, temp would rise rapidly). coasting in neutral makes it go down. The heater being on has no effect, however, once the temp gauge climbs rapidly, all heat from heater vanishes.
The heater starts working again if the temp goes down (meaning I lowered rpms long enough to let things cool down) when I got home I arranged it that I got back in the driveway with the temp gauge almost in the red. I then put the car in neutral and raced the engine, keeping the RPMs up to 5 for 2 minutes. It had no effect (temp did not climb) I let the engine cool down a little and tried again in Neutral. no go. unable to make temp climb while parked.