Hi all, So 2 years ago, all of a sudden, DaveO's engine temp gage began reading cool and the heat stopped working very well at all. Barely enough to take the bite out of the air. It's a 93 Ford Ranger with a 4 cyl, 3.0 L with 370 K miles on it (It is all original cept for the clutch, runs fine and it still doesn't burn oil) Two years ago, we replaced both temp sensors, flushed the radiator and the heater core with water and compressed air, replaced the water pump and the thermostat, checked the operation of the thermostat in a pot of water, checked that all hoses were unrestricted and that flow through the heater core was unrestricted. the heat didn't work unless the radiator hose was clamped shut. It would work a little better with cardboard in front of the radiator. Of course it used to work just fine and suddenly stopped working, so it should work jsut fine without any need for weird modifications. Last weekend, we needed to change the timing belt, so while we were in there, we re-replaced the water pump and thermostat with motorcraft brand stuff, we checked the operation of the thermostat in a pot of water, replaced the radiator and burped the system very very carefully and thoroughly using a funnel mounted to the top of the radiator (with the front end jacked up and the engine repeatedly revved and heated and cooled and reheated to get out all the air. Air came out for a long long time The heat works marginally now, but not like it should. the engine temp gage is reading cool, too. I am completely baffled.