johnson 35hp only pumps water at high idle

[relics hunter]

I'm stumped, it has a new water pump but it will not let me drop down the idle. if I do it heats up and as soon as I raise it back up it starts pumping fine and cools right down. Any help with this is appreciated.

 

[oldboat1]

temp issues aside for a moment, is it getting water up to the powerhead at idle (water out the tell tale or the exhaust port on the leg)? Are you running on muffs? (If running on muffs, can't tell much of anything about water pump function). Should list your year and model -- haven't searched for earlier posts, if any on this motor.

 

[relics hunter]

temp issues aside for a moment, is it getting water up to the powerhead at idle (water out the tell tale or the exhaust port on the leg)? Are you running on muffs? (If running on muffs, can't tell much of anything about water pump function). Should list your year and model -- haven't searched for earlier posts, if any on this motor.

The motor is a 79 johnson with new head gasket and water deflectors and new exhaust cover gaskets. It's getting no water at low idle and it's running in a cut down barrel with a level of half the motors leg length. I have done a forum search but all I find is the opposite problem.

 

[oldboat1]

not sure if covered in one of your earlier threads, but guessing impeller might not be keyed to shaft. centrifugal force spins impeller at higher rpms, but pump doesn't function at idle/low idle.

 

[relics hunter]

I pull the foot and check that out and post back. thanks for the insight.

 

[relics hunter]

well I got around to pulling the foot and found nothing obviously wrong. the key seemed fine so I decided to just replace the pump and it now pumps fine so I assume the pump I first purchased must have been faulty from the factory in some way not apparent to me?

 

[HighTrim]

More likely is that the water tube was partially blocked or jammed on a grommet. The second time installing the gearcase you may have lined it up better, or used grease? Always oil the water line, and grommets, prior to installing gearcase on lower unit.