evinrude 1981 7.5hp not pumping water

Gerry3

Cadet
Joined
Jun 12, 2010
Messages
22
Hi Guys, greetings from the U.K.
Recently bought above motor, paid top price for what was advertised as perfect I have fitted new water pump kit and also fitted new w.pump housing.

Compressed air blows through pipes ok, I,ve had bushwhacker line through to 26", (longshaft) when engine is running there is a good pressure of air coming out of the telltale/pee hole pipe so I assume that the impeller is working ok.

Had it apart 3 times, I have thought it unusual for the water pipe that goes to pump to be fairly rigid plastic, on closer inspection I found that it had been added on to the rubber pipe, is that normal or has someone been playing around?

I have also found that inside this rigid pipe there is copper tubing going up quite a distance inside, the copper tube from the pump will therefore only push in about 3/4 inch.

I use a bin to test motor and have filled it to the top to get water right up leg and above the water pump thinking this would prime it, still does not work.

I thought about taking engine off and fitting a new rubber pipe but would appreciate your comments first before taking that route.

Many thanks in anticipation
Gerry
 

the machinist

Senior Chief Petty Officer
Joined
May 7, 2002
Messages
711
Re: evinrude 1981 7.5hp not pumping water

Welcome to iboats forums

Since it is a longshaft, if it was converted, there is usually a short 5" + section of copper tubing that adds the length to the tube when they add the longer driveshaft & 5" housing spacer.

You need to be sure the motor lower unit is deep enough into the water as they will not suck, but need to be immersed.

A guess is that the water outlet grommet between the water pump & the tube may be collapsed when you did the final assembly up into the exhaust housing. Did you grease the grommet?

If there is any doubt of the impeller pumping water, drop the lower unit again & attach a electric drill motor to the driveshaft with the unit immersed in water. Does it pump?
 

Gerry3

Cadet
Joined
Jun 12, 2010
Messages
22
Re: evinrude 1981 7.5hp not pumping water

Welcome to iboats forums

Since it is a longshaft, if it was converted, there is usually a short 5" + section of copper tubing that adds the length to the tube when they add the longer driveshaft & 5" housing spacer.

You need to be sure the motor lower unit is deep enough into the water as they will not suck, but need to be immersed.

A guess is that the water outlet grommet between the water pump & the tube may be collapsed when you did the final assembly up into the exhaust housing. Did you grease the grommet?

If there is any doubt of the impeller pumping water, drop the lower unit again & attach a electric drill motor to the driveshaft with the unit immersed in water. Does it pump?


Thanks for the info, now I'm happier about the copper tube.
Just checked and all is well with the grommet/grease etc. Checked pump with drill and it's pumping, now I'm going to attach a tube to it and see if it will pump to the hight of the engine, if so I'll put the l/u back on and hope for the best lol.

I'm surprised that I had to fill tank to 17" to cover pump, perhaps that was the problem, not enough water.

Thanks again
Gerry
 

Gerry3

Cadet
Joined
Jun 12, 2010
Messages
22
Re: evinrude 1981 7.5hp not pumping water

Thanks for the info, now I'm happier about the copper tube.
Just checked and all is well with the grommet/grease etc. Checked pump with drill and it's pumping, now I'm going to attach a tube to it and see if it will pump to the hight of the engine, if so I'll put the l/u back on and hope for the best lol.

I'm surprised that I had to fill tank to 17" to cover pump, perhaps that was the problem, not enough water.

Thanks again
Gerry



Thanks for the replies all is now well, it must have been the water level:redface:,ticking over like a watch lol.
Thanks again Gerry
 
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