New thermostat overheats

[bobjones294]

Replaced thermostat in a 1961 18 HP Evinrude Fastwin. Put it a barrel of water, Exhaust would spit out water but power head would get unbearably hot. Would even boil water splashed on top of thermostat housing. Would there be an air lock? Should there be a tiny hole drilled in thermostat. Should there be a bit of water in bottom of thermostat cavity?
Regards, Bobjones

 

[boobie]

Re: New thermostat overheats

Did you do the water pump replacement ??

 

[bobjones294]

Re: New thermostat overheats

Yes I replaced the impeller. Took bottom end off, put it in a barrel of water and turn input shaft with 1/2 electric drill and the pump would shoot out water. Took power head off and blew out all channels that handle water. One of my next step will be to put thermostat in water over stove and see if it opens.

 

[nwcove]

Re: New thermostat overheats

dumb question, but do you have enough water in the barrel to have the impeller sumbmerged? it should be at least a couple of inches above the impeller housing.

 

[Rick.]

Re: New thermostat overheats

dumb question, but do you have enough water in the barrel to have the impeller sumbmerged? it should be at least a couple of inches above the impeller housing.

Not at all. I'm always surprised how often more water is the only problem. Rick.

 

[bobjones294]

Re: New thermostat overheats

Thermostat in hot water pot on stove tests O.K. When I put motor in water barrel I dunk it past the cavitation plate so water pump inlet screen is under. Gasket between bottom end and power head was in rough shape so that will be changed on reassembly. After all this I can’t see it having problems.

 

[nwcove]

Re: New thermostat overheats

Thermostat in hot water pot on stove tests O.K. When I put motor in water barrel I dunk it past the cavitation plate so water pump inlet screen is under. Gasket between bottom end and power head was in rough shape so that will be changed on reassembly. After all this I can’t see it having problems.

pump inlet screen only works while underway on the water. in a barrel or idling at the dock, the impeller has to be submerged in water , as it wont self prime.