196? Johnson 6 hp water pump (impeller) question

[pecheux]

this 1968 or 69 Johnson's 6 hp water pump needs the motor to be put in gear (F or R) in order to start the water flow to be activated. Is this normal ? Once primed it will pump ok until the motor is stopped for a while. Thank you.

 

[Bosunsmate]

no way,
is the motor sitting low enough on the transom?

 

[Bosunsmate]

no way,
is the motor sitting low enough on the transom?

 

[racerone]

Water should come out with the exhaust as soon as motor starts.

 

[pecheux]

no way,
is the motor sitting low enough on the transom?

Normal 12 foot Lund deluxe boat. Had a 9.9 hp short shaft mounted on it that ran great for years. Motor is standard 6 hp short shaft. Been using it for many years (summers up here north) Pump always needed engaged gears for 2 to 3 seconds, than pumps ok at idle and neutral for the whole day.

 

[pecheux]

Water should come out with the exhaust as soon as motor starts.

Then we obviously need a new impeller. Unless there is another reason why it need to be primed after just sitting there for days. The boat is docked with motor in the down position all week long. Used on weekends only. Thank you

 

[Bosunsmate]

well if thats what works for it then id just leave it, im not sure mechanically how that happens though as the waterpump is being driven exactly the same in neutral as it is in gear.
I suppose you could replace the impeller being part of normal maintenance and all and see if that changes things

 

[pecheux]

Still beats me. Impeller starts pumping water as soon as a gear is engaged, then continues to pump correctly at idle. Like it first needs to be primed upon starting the motor. I'd hate to go true changing the impeller if this is normal for that age OB.. (1968 or so)

 

[Tim Frank]

That would never be an intentional design, and as stated, makes no sense as the impeller power is independent of the gear case.
When did you last replace impeller?

 

[relics hunter]

it sounds to me like the upper water intake plate is above the water line and preventing it from making the vacuum needed to draw water to the pump, thus when you put it in gear it forces water up the lower intake and voila vacuum met and can then draw the water itself.

 

[racerone]

You risk ruining the motor if you keep operating this way.--Time for inspection and a new impeller.