81 300SD low engine temp problems
 

My temp gauge rarely moves very much. It started a few months ago and got progressively worse. I repaced the sensor on the block (I bought a new one years ago and decided to put it in). No change. I have ordered a thermostat. Question, if the thermostat fails, does it default in the always open position? If so, that would explain the behavior. My trips are fairly short now. But, as I recall, an interstate drive did cause the gauge to move to normal range. What is the best way to get rid of airlocks when I change the coolant and thermostat? Thanks

that's it

start it up
 

and run til the stat opens. shut it off and check water level. do it twice more.

tom w