With the engine cold on startup you could check the water pumps ability to move coolant by pulling a hose off at the heater core. It should be pumping coolant even at idle with more movement at higher idle speed. The engine temp would likely be increasing very quickly if the pump was not circulating coolant.
With the engine cold on startup you could check the water pumps ability to move coolant by pulling a hose off at the heater core. It should be pumping coolant even at idle with more movement at higher idle speed. The engine temp would likely be increasing very quickly if the pump was not circulating coolant.
I pulled the thermostat out and it's not fully open until a little of 200 F . It's a 180 f thermostat. It also opens very slowly. Coolant is circulating as the cab heater blows warm air after running for 5 minutes or so. I did notice that right when I flip the cab heater on the temp gauge drops down about and eight of an inch and goes back up immediately after turning the fan off. It happens immediately, so I know it has nothing to do with the fan blowing on the heater core cooling down the coolant.