How do i check the water pump on my 351M?

Question

Its in a 1977Ford F-150 4x4 if that makes a difference. My truck has been overheating, it overheats after driving at 10-15mph for 5 minutes, its retarded. i thought it might have been the thermostat so i changed that and it is still doing it. So i am thinking that it is the waterpump, anybody know how to check it or have any ideas as to what it may be? thanx.

Answer 1

start the engine with the rad cap removed, you should see the water moving slightly, when the engine warms the water level will rise and when it gets to being hot, the water should drop because the thermostat has opened. also you can start the engine with the rad cap on and squeeze the top rad hose it should be firm due to water pressure.

Answer 2

1st start truck and get it up to operating temp, with cap off. You should see a drop in water leval when thermostat opens, then you should see water moving through the vanes in the radiator if not the pump is not working, if it is, then is the water bubbling or foaming? This is an indication of a cracked head or gasket, if no, is the vanes in the radiator clean and the water running freely? if not have you radiator vanes rodded at your local shop. A '77 I would expect that.

Answer 3

You could have a clogged radiator, the clutch in the fan might be bad and not spinning the fan fast enough to cool the engine at low speed. Low coolant level will also do it.

You can pull the radiator cap off and let the engine warm up, you should see the coolant flowing in cycles as the thermostat opens and closes. good luck.