86 johnson stops pumping water, underway

[merc350]

i have a 86 johnson 25 hp , its only done 12 hrs since new.
it had a new impellor replaced 12 months ago, (sitting around) and it pumps water out the telltale very nicley.
problem is when i get underway, all of a sudden it will stop pumping water out the telltale, and start to get hot. after paddeling back to shore, i can restart the motor and it will work again. seems to be only under load in gear, that it stops. then i take it out again, and after about two minutes it stops again and starts to get hot again. ~FRUSTRATED!~ HELP??
does this motor have a thermostat?>

 

[tashasdaddy]

Re: 86 johnson stops pumping water, underway

check the impeller. yes it has a tstat. but the tstat would not stop the water flow.

 

[HybridMX6]

Re: 86 johnson stops pumping water, underway

If it only happens underway, and the water flow totally stops, could possibly be tilted too far up, or mounted too high on the transom.

 

[ENSIGN]

Re: 86 johnson stops pumping water, underway

The cavatation plate should be even with the bottom of the boat,if not it could suck air and overheat.trimming it up to far could also cause problems.

 

[merc350]

Re: 86 johnson stops pumping water, underway

hi, its a long shaft, have checked depth, it sits almost a foot under the bottom of the transom.
when it gets hot, its spurts and steams out of the telltale.
we took the gearbox off, and checked the impellor, and it looks fine, have to squish it to get it back in the pump housing.
its really frustrating, as the motor is so new.
i can run it at idle all day and no hot.