Reply To: 1961 Johnson 40 (RDSL-23) stops pumping water

[jdunham]

This is all great stuff, I am learning a lot here.
Yes, I am abandoning the idea of the other gearcase. It was just an idea, and not a great one.

Bill,
This boat has not been on a boat in a lake since it was taken apart 10 or so year ago (time flies, it may have been sitting for even longer). My father has no recollection of an overheat issue.
I have been assuming that something was either clogged, corroded, or cracked from mice, salt, or ice in that time. My (limited) experience is with the 56,57 big twins and RDs that have the single water tube, no thermostat, and spit lots of water, even in a barrel.
I started down this pump rabbit hole through an abundance of caution about overheating and wrecking a motor.

I will try to get this motor on a boat for a better test, pending some gearcase work, see below. The boat it is supposed to be on is not presently seaworthy so I need another boat option for the long shaft.
Other than excessive spray and hanging down so deep, is there any danger in running it on my other boat with a 15″ transom? 15′ aluminum, rated up to 60HP.

At what temperature should the sensor(switch) on the head close? I can wire it up to a battery and light or just watch it with my multimeter. I will also keep an IR thermometer on it to confirm that it closes when it is hot enough.

Pictures of the impeller housing and SS plate attached.

Fleetwin,
I did your suggested leak down test. I knew the gearcase was leaking. It had water in it when I got into this motor, water that had been sitting for at least 10 years so I have assumed the bearings are trashed. I had refilled it with some gear oil that I had on hand for my tank testing of the motor, planning to deal with the gearcase later.
I did not know how bad it was leaking. With the water tubes installed, water runs down by the driveshaft seal and comes back up around the shift rod. That is maybe 13″ of head. It is not a stream, but a steady drip. Whether or not enough exhaust would take the opposite path and cause the pump to stop pushing water I dont know.

Maybe I need to change gears for a while and start getting some heat/penetrating oil on the skeg screws so I can change out the shifter o-ring. It seems a little silly to put seals into this gearcase but the $25 seal kit might be the most practical thing at this point.