71 25hp Johnson running hot?

[davidmbv]

Hello, I have a 1971 25hp Johnson. I replaced the thermostat and a bunch of other parts including ignition components, rebuilt the carb, new impeller, gear oil etc.
I noticed after running it, one side of the cylinder/ crankcase gets real hot. Almost to hot to touch. If facing the motor where the carburetor sits, the left side of the cylinder is real hot to the touch. I pulled the thermostat after it was warmed up and noticed it wasn’t open but it’s brand new (OMC) and it looks as though it was likely letting water through as everything looked wet in the housing. I also tested it in a bowl of hot water and confirmed its functioning. Anyway, is this normal to have one side real hot? I’m concerned I may have overheated the motor recently when I ran it hard on one cylinder unknowingly. I pulled the flywheel and noticed one condenser wire was shorted out when it rubbed the flywheel and this caused the loss of one cylinder. It’s now fixed and seems to run ok in the tub but haven’t ran it on the water yet, was hoping to get some info on possibly overheating.
Thanks in advance

 

[racerone]

Yes one side of the motor is the exhaust cover.----Gets hot if no water.----Water tube must be put into exhaust housing first , and not the pump first.-----Water in your test bucket MUST be 6 or 8" above the impeller.

 

[davidmbv]

The test bucket is plenty deep and also noticed it was real hot to touch when I was running it in the lake.
I had a shop do the impeller few months ago but I did all the electrical/ignition work. Looks like I may need to check the shop’s work and learn to do the impeller.
Is there a way to test if it’s getting enough water? Or if the water tube is installed correctly without dropping the lower end?
It seems to be spitting plenty of water. Sorry if these are amateur questions. It’s been a fun learning project of mine .

 

[F_R]

There are two water flow routes through that powerhead, one route is thermostat controlled, the other not. It is possible that one route could be plugged up. On that thought, when you had the thermostat cover off, did you see any kind of a rubber plug? If so, remove it. That was a service bulletin fix for motors used in icy water. Having said that, I've never installed the fix, or even seen one. We have very little icy water here in SW Florida.

 

[davidmbv]

I’ll try blowing compressed air through the thermostat route. It does not have a rubber plug but good idea to check that.
also, I checked the compression and I have just over 115lbs on top #1 cylinder and 120ish on number 2. Is that good?
also, I borrowed a temperature laser gauge and will check the temp on the motor in a bucket tonight. Does anyone know what normal operating temp is ?
thanks

 

[davidmbv]

Well I tested the temp in the bucket and the left side(non exhaust cover side) ran up to 140F then after few min dropped to 130-135. In guessing it’s running at normal temps. The exhaust side ran a bit cooler. I flushed water through both holes in the thermostat housing and saw water running out below .