powerhead not cooling

[littlemess]

1977 Johnson 55hp. Model 55EL77. New water pump installed. With the lower unit off, and in water, we can see that it is pumping a large volume of water by turning the shaft with an electric drill. Once the lower unit is reattached and the engine started, the warning horn went off after abour 2 minutes running at idle. There is no tell tale on at 1977 55 hp. What should our next step be?

 

[Daviet]

Re: powerhead not cooling

First make sure it is actually overheating, might have a bad temp sensor, can you hold your hand on the cylinder for 2-3 seconds without discomfort?
You might also check the thermostat, could be defective.
Are you sure you got the water tube installed correctly?

 

[littlemess]

Re: powerhead not cooling

Ok. just changed the thermostat. Still overheating. too hot to touch. Also have water gushing out of the exhaust relief ports. Is this correct?

 

[kenmyfam]

Re: powerhead not cooling

Salt water motor by any chance ???
How was it before the water pump change out ???

 

[littlemess]

Re: powerhead not cooling

What's the best way to check the water tube connection at the power head?

 

[Cofe]

Re: powerhead not cooling

Only way to check is to drop the lower unit again. Once you have taken off the lower unit, duct tape a water hose onto the water tube. This will tell you where your water is going. Motor doesn't have to be running to test this. You could have a bad upper water tube grommet.

Also if this is a salt water motor, you could have a accumulation of salts in the water passages.

Here is a pic of that upper grommet #95.

 

[littlemess]

Re: powerhead not cooling

I just picked up the motor two weeks ago. Don't know the history I'm in Wisconsin, I believe the engine has always been here. I decided to purchase it because it has great compression 150 psi in each. Out of frustration and for the fun of it, my son and I pulled exhaust covers and found the insides extremely clean. No evidence of blockages. Difficult to tell by just looking with a flashlight but the top of the water tube seems to be snug.

 

[Cofe]

Re: powerhead not cooling

When you removed the old water pump, were the vanes all still in place?

If not, a part of one may have made a blockage down stream.

 

[littlemess]

Re: powerhead not cooling

I just thought I'd change the impeller and housing as part of refurbishing the motor. The impeller I removed was actually in very good shape.

 

[Cofe]

Re: powerhead not cooling

If it is pumping water, and the head gets hot, there can only be a few things that could be wrong.
Blockage
Bad thermostat
Didn't get water tube in the water pump grommet.

If you are using a tub of water to run the motor in, the water pump area needs to be under water.

If it were me, I would hook a garden hose to the water tube with the thermostat removed and see if water gets up to the thermostat.

Put the thermostat in hot water and see if it opens at 145-160 degrees.

Hope you can find the problem.