1978 Mercury m500

[Crush23]

I have a 1978 Mercury m500 Serial: 4966982 that I just bought. I wanted to check to see if it was cooling and spitting. I started it in a big cooler full of water but no water came out. I made sure that the screens were sumerged in water but still nothing. Did I do something wrong. Is there some trick to test these motors. I scared that it won't cool and I'll reck the motor.

Any help with be great..

Thanks in advance.

Crush

[boats.net]

That would not be deep enough in water, water should be about 4 or 5 inches above cavitation plate. The water pump has to be submerged in water to prime.