Help! Honda 7.5 Overheating

[Doug in Santa Rosa]

I really need help.

My 7.5hp has performed nearly flawlessly for us for many years. But now it is running HOT! We were going to take it out for the first time this year. I ran it in a garbage can full of water to test it, and I was not getting a good water flow out of the pee tube.

I have just finished replacing the impeller, the water pump housings, the water tube seals, the gaskets, verified all tubes and passages are clear...in short, everything I could think of.

Here's what the motor still does, which is exactly what it was doing before I disassembled it and replaced all the parts:

Upon starting, I get a decent stream of water out of the discharge tube. The stream lasts for about 3 minutes, after which the water turns from cool to warm to hot to BOILING HOT to steam with no water at all. If I let it run for a few seconds more, the water flow will start up again for a few seconds, turn to boiling water and then just steam again. I turn it off at this point. If I let it cool down and start it again, it does the same thing every time.

The motor has never been run in anything except clean lake water. There is no thermostat in the engine (it had been removed years ago). The inlet port is perfectly clean.

Can anyone help?

 

[hondadude]

Pull the small hose that goes over the top of the engine to the intake manifold. Run the engine and see if water comes out of the hose at the intake manifold end. If it does not, it could be clogged or the tube where is connects at the other end could be clogged with debris or old impeller pieces. Stick a stiff wire into it and see it you can clear it out. This is the simpliest thing that I know to do for starters.

Mike