[Jack Innes]

Originally Posted by Lynn Eades

BTW the flathead block has an entirely separate system for each bank, that is only connected by the radiator and fan belts.
That means if it wasn't for the water mixing in the radiator,the water in each bank would never meet.

This can lead to undetected problems if the water circulation stops on the side without the heat sender. That bank of cylinders can become overheated before the temp. indicator shows trouble. The bottom line is not to trust the indicator if you suspect something is not right. Later flatheads had a sender on each side. Worth noting - while they look alike, the dual senders are not the same - the second one is a switch that, on overheating, closes & sends the indicator to the full hot reading.