thermostat stuck closed?

[glenn]

From cold, the van warmed up as usual. After 5 minutes of driving I noticed there wasn't much heat coming from the heater, glanced over to my temp guage to see it alarmingly high (near the top - not red though). I pulled over and let it cool. The radiator was full but the reservoir was empty (it was full when I checked it last week). I topped everything up, and the same thing happened again. This time I noticed that the temperature went high, then just stayed there. The van felt fine, still running smooth, but the temperature stayed high - just below the highest white mark, and not into the red.

I think the thermostat could be stuck closed - it explains everything except the loss of coolant from the resevoir. Any ideas?

Thanks, glenn

[FalcoColumbarius]

Maybe the temperature sensor. I had an instance, similar: Little more than idling down a hill when I noticed my temp gauge going high. I stopped and let her idle with the lid open (seat). Delicat suggested the sensor may have come loose and wiggled it a little ~ everything has been fine ever since.

Falco.

[glenn]

I dream of solutions like that. Just wiggle the sensor and it's fixed. While these kind of fixes seem to never work for me, you can bet I will be out there in the morning wiggling.

Thanks Falco

[jessef]

Hopefully it's the wiggle.

If not, you can test your thermostat in a pot of hot water to see when it opens.

If it doesn't open, then thermostat is suspect. If it does open, sensor is suspect. If both sensor and thermostat test good, then you may have blockage somewhere. Usually calcium buildup in the rad. When was the waterpump done last ?

[glenn]

OK, so either my sensor is faulty, or my van stayed hot all night. I'm going with the faulty sensor - unless perhaps I'm having problems with the fundamental laws of physics.

For once it's the simple problem. Glenn

[FalcoColumbarius]

You know, I got this crazy hair brain (an' most of that is gone) idea: We climb a hill and the temperature rises; we pull over and cool down; when cool we open the rad cap and low and behold ~ it's all covered with scale and the radiator is only operating at 70% capacity ~ so we get a re-core. What about the heat exchanger? It is standard protocol when replacing the rad to replace the heat exchanger (heater core) as well. Why don't we at least try to clean it out? It's the same principle as a radiator and the coolant flows through it....

Have you checked your rad cap for minute, diminutive hairline cracks in the "O" ring seal?

Falco.