Kettle Clinic

Due to slight overheat I wanted to check if my GT750A pump was working. I removed the thermostat housing and stat and slow drained the coolant by partially loosening the drain plug until the level had dropped to just above the bypass hose inlet hole in the bottom of the stat housing. By running the starter motor with plugs out you can clearly see the action of the impellor sucking the coolant down the bypass hose . see video below. This is a much easier check than draining all the fluid, exhausts off, removing the pump cover on the bottom of the engine and looking for rotation with a mirror. Also it shows the impellor is shifting coolant which seeing rotation of the pump shaft does not establish. Hope this helps someone.

https://youtu.be/ex2dKm1ZvX0