1963 Johnson 3hp overheated

[beruken]

Got my little motor running after a bit of maintenance, had not been used in over 25 years and it overheated. I had previously checked the impeller and assume I had the water intake tube properly inserted in the impeller housing. There seemed to be a bit of rubbery grit in the lower end. I also checked if I could blow air through the tube into the power head and I didn't find any air coming out. That tube is so small it's hard to find a way to circulate water.

Is there any way I can test if water will actually flow through the power head and where would it be exiting from?

 

[F_R]

It dumps into the exhaust housing, directly below the powerhead. You should be able to blow through it though.

 

[HighTrim]

I shoot compressed air up into the water intake tube while my gearcases are down to ensure that the cooling circuit is free of debris. Could even use the garden hose.

 

[Bnbvetter]

I have a 1968 3 hp. Should be similar. But mine has three different routes the water can take after the pickup tube. So unless all passages are blocked, the test wouldn't really work. Mine was overheating and it turned out the water passages in the head were packed with dirt and gunk and stuff, keeping the water from properly flowing. If you go ahead and replace the head gasket (and possible the exhaust housing gasket) you will have a better chance at finding the culprit. With those parts off, I shoved a metal coat hanger into all the water passages. And the ones I couldn't get the coat hanger to bend around, I blew water through. But your best guess is to check the head forst

 

[beruken]

Thanks all. I guess a new head and exhaust gasket is in order.

 

[Bnbvetter]

I only spent $14 on both including shipping. So it's a cheap enough place to start.

 

[beruken]

So i'm listing to these stories from my brother about this motor and his attempts to use it some 25 years ago and as I'm taking off the exhaust i had noticed blue gasket compound on the outside of the power head. Well, when i got it opened I found the gasket compound had completely filled the intake hole... I think I'll leave it at that.

Auto Zone has gasket material for 6 bucks and I don't have to wait days. Better get out my razor blade.

 

[HighTrim]

More is not always better!

I cover the gasket, but it in one of my wifes magazines with the shiny pages, close magazine, then open and pull it out, leaves it perfectly covered. Not so perfect is her reaction when she finds out! Tip compliment of F_R, angry wife warning compliments of yours truly.