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1997 40 hp Mercury outboard...water pump replaced and works until the boat planes out.

M

Mike Stone

New member
Hello! I just replaced my water pump because it wont pump a steady stream out while the boat is on a plane. the new one does the same as the old one. water pumps just like it is suppose to until then and will start to spit and spray it with steam. Any help with this will be apperciated!!


Thanks
Michael
 
Sounds like the intake is breaking the surface (maybe).

Short shaft motor on a long shaft transom?

Motor tilted up a little?

Thrust pin inserted a little high?

With the motor in it's "down" (running) position the cavitation plate should be roughly level with the bottom of the hull. If it isn't the motor is mounted too high.
 
Thanks for your response!! Well I was thinking the same thing about these points you brought up....The motor is a long shaft and its all the way down on the transom and the cavitation plate is within an 1". The thrust pin could be a problem its in the top hole but I dont remember it being a problem before...But I will check this out to see if it helps. I was thinking that something on the boat of the boat was causing a air pocket but there wasnt anything there that I could see that would cause that.

Im just lost on this one.

Btw its mounted on a 1986 Basstracker TX-17
 
could anyone tell me if this could be a head gasket? pumps great at idle but when you raise the RPM up to plane it starts spiting water and steam leads me to think its pumping hot compression into the water jackets. Tell me what you think?
 
ok racer one I was wrong the manual makes it look that way but its not a head but a cover I never seen anything like it...so what the heck can it be then?
 
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