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willie
08-01-2003, 12:04 PM
" I have a 1988 50 HP Force Model 50X8B, S/N 1388.
I have replaced the head gasket, thermostat, and water pump impeller the motor is on a 1988 15' bayliner it runs fine with just me in it but when I have another person in the boat it over heats. I think the motor has alot of hours on it I am going to check the compression which should be 135 to 150, I am thinking that when you put a load on the motor that's what causes it to over heat and may need to be rebuilt, what is the minimum compression which indicates bad rings.

Thanks for your help Bill "

Puzzled Pete
08-01-2003, 06:47 PM
" Before I spent a bunch of effort on it, I would ask a couple questions, like:

Is this a recent problem or has it always done this?

Is something else changing when loaded with people, like motor attitude relative to water flow? I know it sounds stupid but...with motors..

Is the motor properly proped? Too large a bite may be ok when you have one person but extra weight may cause the motor to overwork with the wrong pitch on the propeller.

Do you have the right heat range and "gap" settings on the spark plugs? (Another factor sometimes in over heating.)

Other than that, difference in compression between pistons would be of more concern to me than all cylinders having lower than factory specification compression levels.

Build up of "Lime" sediments in cooling will cause overheating when loaded that will otherwise work fine when running at low rpm or not running with load.

Hope one of these will be the cure for you,
Good luck. "

tonyob
08-02-2003, 11:23 AM
"Bill,

You probably have a problem somewhere in the cooling system. That boat/engine combination is very hard on the engine with two adults onboard. In order to get it to plane and maintain the plane, the engine works very hard, and so generates lots of heat. Usually the problem area is either the exhaust plates or gaskets, or the gasket at the base of the powerhead.

Tony"

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