'62 Johnson 40 h.p. Cooling system

[johnb]

The titled motor is not circulating water through the cooling system. When I start the motor, no water is discharged from the rear cooling water exhaust "hole" (about the size of a nickel on the rear of the shaft, midway up the shaft). I had it apart and checked the impellar which seems to be in good shape. The impellar is keyed to the shaft and should be turning but no water seems to be discharging. Everything seems to be put together well including the direction of the impellar. I'm stumped???

 

[F_R]

Re: '62 Johnson 40 h.p. Cooling system

OK, first question has to be where are you running it, on a boat in the water or in a bucket? If in a container, it has to be deep enough to submerge the pump before starting.

Is it not discharging any water at all? It should blow a fairly fine mist when the thermostat is closed and a heavier one when the 'stat opens. It may not even get warm enough to open the thermostat if just running at idle.

If you have ripped the thermostat and all it's guts out of the head, there is your problem. The plastic housing and relief valve has to be in there.

 

[johnb]

Re: '62 Johnson 40 h.p. Cooling system

I did remove the thermostat a few years ago and didn't notice a cooling problem. How does removal of the thermostat prevent circulation through the motor?

The thermostat is all brass (I believe). I could not see any plastic components.

 

[tmcalavy]

Re: '62 Johnson 40 h.p. Cooling system

Your 40 may be like the earlier 35 hp's...FR can tell us that. Water goes into the system from the pump, but goes back the pump through another tube until the thermostat opens. Once the thermo opens you get some discharge through the outlet on the leg. I think the thermostat is 150 degrees, so it will run a little while before the thermo opens. Or, it could be different.

 

[tashasdaddy]

Re: '62 Johnson 40 h.p. Cooling system

62 is the slient type, with 2 water tubes.

 

[F_R]

Re: '62 Johnson 40 h.p. Cooling system

The above is a pretty good explanation. However, there should be some discharge even when the thermostat is closed. Amount of discharge varies according to the thermostat situation at the moment.

However, he says he removed the thermostat.

The thermostat sits in a black plastic housing. There is a nylon check valve and spring below the black plastic housing. If you remove the housing and check valve, exhaust gasses are allowed to flow back through the water tube going back to the water pump. Air (exhaust) entering the pump kills the pumping action.

That stuff was put in there for a reason. There is no reason to take them out.