Cooling issues on 302 inboard motor

[splattgraphics]

So my '74 Crusader powered inboard lake skiboat overheats, but mainly when it is shut off after reaching proper running temp, then restarted. Seems that if I start it cold, run it, pull skiers, whatever, it will stay at temp, but if I shut it down for a minute and then restart, it'll heat up. At that point I shut it down, wait a minute or less, restart it and it always drops back to zero and then runs fine at temp again. I have replaced the thermostat and water pump on this '74 ford 302 block, but to no avail. Any guesses?

 

[mkast]

Re: Cooling issues on 302 inboard motor

Verify temperature gauge operation.

 

[splattgraphics]

Re: Cooling issues on 302 inboard motor

The pump on the block is new. The raw water pump I cannot speak for, but it hasn't been replaced or rebuilt in recent memory. so is there a way I can test it? As for the temp guage, it so consisitently behaves the same way with the shut-downs and all, I am assuming (I know...) that it functions. So how does one test the guage and sender for accuracy? JC

 

[rbh]

Re: Cooling issues on 302 inboard motor

on my old ford car I would get the same thing and determined that it was a steam pocket forming around the sender thermostat area, but this was because we had air in the system, could your engine water pump be on its way out?
rob

 

[Bondo]

Re: Cooling issues on 302 inboard motor

The raw water pump I cannot speak for, but it hasn't been replaced or rebuilt in recent memory. so is there a way I can test it?

Ayuh,... The water cirulating pump on the front of the block Rarely fail,+ when they do it's the Seal...

Raw water pumps have a Rubber Impeller that should be serviced Annually....

 

[gadget73]

Re: Cooling issues on 302 inboard motor

What they said. Most temperature problems are caused by the raw pump failing. The circ pump doesn't actually do very much. When they go bad, they leak and/or the bearings get noisy. I do my raw pumps at least every 2 years, and pretty consistently there is nothing left of them at a 2 year interval.

Also, FWIW, the 302 in both of my cars does something similar. Most engines do actually. When the engine stops running, the coolant doesn't move so you get hot spots. Usually all I have to do with mine is let it idle for a minute or two and it moves the hot water through the radiator, and the temp drops right back down again.

 

[WizeOne]

Re: Cooling issues on 302 inboard motor

Unlike Black Anchors, OMC Stringer impellers should be replaced at least every 15 years.