Thanks for all the comments and suggestions for the 1941 GMC cooling issues. Here is what I have found:
Capillary type heat sensor IS located at the back left of the engine. Very close to the exhaust manifold. It reads 230-250 degrees F while the engine gauge is at 195
The thermostat is a 180 degree thermostat. I changed to a 160 degree and it does a LOT better with the normal engine gauge reading of 180 after 40 minutes of driving. With or with out the AC being on. Seems as if the engine operates (at the rear temp take off) 20 degrees hotter than the thermostat setting.
It climbs to 190 degrees by the capillary gauge when I stop and depend ONLY on the electric fan. Once moving again it comes down to 180...seems as if the electric fan is not enough air movement for all ranges of operation.
There is a shroud on the electric fan that came with it new. The radiator is a Champion brand which came with a 16 pound cap. I changed to 8 pound and have an overflow container.
The electric fan was installed as the pulley arrangement required moving the radiator forward to accommodate the Alternator (12V) and the AC compressor and there was not enough room available for the mechanically driven fan.
Very possibly the improvement may be largely from my burping the system and purging trapped air. After cooling, the radiator sucked up almost all of the 50/50 coolant blend from the tank......that was a new experience.
Thanks again......lot of help here!
rb
