1963 Johnson super seahorse 40hp, runs rough when hot

The motor seems to be sucking water but not sure if it's enough....when you bring up the rpms more water comes out..Pretty sure this is how its supposed to be...as soon as it gets hot the motor begins to back fire and run rough..is this because the motor is not being cooled properly or because this mixture is to rich???It is backfiring out of the exhaust, this usually means it's to rich..all your help would be appreciated, thanx
Terry

Re: 1963 Johnson super seahorse 40hp, runs rough when hot

hey, hope I don't have to start a new thread...I pulled the bottom end off, submerged it in water and ran shaft with drill, the impeller is pumping lots of water, comes out at a good rate..my question is....the motor does not have a thermo stat or relief vale in the housing. Could this be directing the water straight back back into the pump relief?????there isn't much water coming out of the exhaust, mostly steam

Re: 1963 Johnson super seahorse 40hp, runs rough when hot

What have you done to the motor? Tune-up? Carb clean/rebuild? Did you replace the impeller? If so, what was the condition of the old impeller? Were you running it in a tank or on the water? Need some basic info before we can diagnose your problem.

Re: 1963 Johnson super seahorse 40hp, runs rough when hot

carb clean-up, new plugs....got a deeper barrel today, pulled bottom end off, impeller looked to be in good shape, ran drive shaft with drill and good flow coming out of the pump. about the rate of a hose with tap 3/4 open..would probably be more if drill ran faster....the thermostat was removed from housing, there was still a valve on a spring in the bottom, I took this out..I think maybe now the water is just going straight into the return tube for the pump...will put it back in today and try again...motor runs very well, just getting to hot I think....the motor is the 20" shaft and there is a small hole part way up the housing, i believe this is to let water in on top of the pump,not sure if level was quite above this before..will try with deeper barrell today..
Terry

Re: 1963 Johnson super seahorse 40hp, runs rough when hot

scaryt5 said:

carb clean-up, new plugs....got a deeper barrel today, pulled bottom end off, impeller looked to be in good shape, ran drive shaft with drill and good flow coming out of the pump. about the rate of a hose with tap 3/4 open..would probably be more if drill ran faster....the thermostat was removed from housing, there was still a valve on a spring in the bottom, I took this out..I think maybe now the water is just going straight into the return tube for the pump...will put it back in today and try again...motor runs very well, just getting to hot I think....the motor is the 20" shaft and there is a small hole part way up the housing, i believe this is to let water in on top of the pump,not sure if level was quite above this before..will try with deeper barrell today..
Terry

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If you run without a thermostat, that valve still needs to be in place or the engine will get little water.

Re: 1963 Johnson super seahorse 40hp, runs rough when hot

than you, that's exactly what i needed to know