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Posted

I would say that sounds like a water pump or maybe a thermostat issue. Should be a relativley easy fix. I would not run it until its figured out you cold blow something

 

Hey guys. I got a1975 johnson 9.9. when I get past 3/4 throttle it doesn't throw water out the port on the back of the motor. This water is for cooling right?

Posted

Yes that's a strange problem indeed.. Usually when the water pump is worn the water doesn't spit at low RPM.. I would pull off the foot and change the water pump anyways, if you can't remember the last time it was done.. You may find a broken fin on the impeller or some other issue causing blockage.

Also, check the pee port for any blockage

Posted

Water pump replaced last year. Pee port free of debris. The transom is an old home made jobie. I wonder if the transom is a bit too high. Where should the a motor air relative to the bottom of the boat?

Posted

The cavitation plate should be within an inch of the bottom of the hull.

 

Usually, the "pee" water is just extra over flow, or an indicator that your water pump is working. Most of the hot water, that is used to cool, should be coming out of your prop, or exaust ports on the back of the engine. As long as you have water coming out there, you should be fine. Does the "pee" water get hot? It shouldn't on most engines.

 

It is odd that you have flow at low rpms, and not high though....weird.

 

S.

Posted

I worked on a 20 yammy, also had lots of water at idle no water past half rpm. Ended up being water pump impellor even though it looked fine. We wasted a lot of time looking for plugged ports, thermostat, etc.

Posted

Maybe the impeller got installed reversed, I have heard that happening. When you get up to speed the vanes can't close all he way and pressure drops

 

 

 

This problem seems to be relatively new.I bet his motor is a inch or two high and that's why it's showing up at high speed.

Posted

sounds like the motor is sitting too high on the transom,as the boat planes the bow drops the transom rides higher and the motor sits to high to draw in water...my buddy had the same problem a few years ago,

Posted

I would agree that maybe the motor is sitting to high.

 

Did you install the new impeller yourself, or have a mechanic do it?

 

Some of the older motors have a plastic woodruff key that hold the impeller in place. It might have been installed incorrectly such that the impeller will spin a little at low RPM and spit water, but at high rpm is slips.? Not likely, Just a thought..

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