1882 40hp cooling and normal temperature

[davebad22]

Relatively new to me 1982 40hp Merc. Had issues of overheating. Found impeller in very bad shape. Replaced impeller, cleaned out some debris and put in new thermostat. I have a good stream out the tell-tale-hole.
When running the outboard submersed in a tub (water just above the “trim tab plug”) the side of the “leg” as I have heard it referred to (exhaust manifold outer cover, left side) below the exhaust outlet and down to the waterline gets hot. How hot should this get? I can put my hand on it but it is hot. When I run the motor without the thermostat it does not get hot.
Is this normal? Does it make a difference out on the open water submerged deeper and move through the water?

Thanks, Dave:/

 

[JUSTINTIME]

Re: 1882 40hp cooling and normal temperature

normal operation
put the t stat back in

 

[davebad22]

Re: 1882 40hp cooling and normal temperature

JT, Thanks for your quick response which encouraged to move forward. I took my boat out on the local canal to see if all my inquiries, reading responses like yours and the work that I did paid off.
Success! The motor ran great, and stayed cool. My only mistake (that I know of) was the orientation of the reverse locking cam. Which is now fixed.

Thanks Again

 

[Texasmark]

Re: 1882 40hp cooling and normal temperature

Thermostat should start opening at 120 F. (Normal on a hot water heater in your home is 140 F (for reference on how hot is hot). Add that to the heat of the exhaust and you have your heat.

Mark