1957 10 Hp overheating

[ejs68]

Hello. THe engine is a 1957 10HP Johnson Seahorse. Model #QD18H Serial #1674080.<br /> I am having trouble with the engine running hot. So far I have replaced the head gasket, checked all water jackets, and resealed everything. I have blown air through the water inlet and it came out of the exhaust, so I assumed everything was clear. After starting, the waterjacket and head are still getting discolored from too much heat. It has not been run in about 10 years, and starts on the third pull. Impellor was replaced, and still looks good. Soft, and a tight fit in the housing, not a lot of wear. You can tell it is not slipping on the shaft, there are no wear marks on the shaft or impellor ID. <br /> Any help would be greatly appreciated. Thank you, Ed

 

[Paul Moir]

Re: 1957 10 Hp overheating

I don't want to overlook the obvious here, but are you running it in sufficient water? Those pumps won't prime unless they're submerged at startup.<br /><br />Is any water at all coming out of the idle relief and water exit on the back of the outboard?

 

[ejs68]

Re: 1957 10 Hp overheating

Paul,<br /> Running it in a garbage can full of water. Thinking that is enough. A little water is coming out of the exhaust.

 

[Paul Moir]

Re: 1957 10 Hp overheating

Have a long hard look at the intake to the water pump. Perhaps even pull the whole lower unit off, and wind it up in a tub of water with a drill to see if it gushes properly.<br /><br />You should have a good amount of water coming out the exhaust. '57 ought to be pre-thermostat so everything the water pump moves should come out with the idle exhaust.