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1972 65 Hp Waterpump

H

HumberJewel

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I have 2 water pumps for this motor. One with a solid aluminum housing and one with a plastic housing.
Neither pump had a gasket between the pump housing and the wear plate. (I also have a pump from a 1974 70 Hp that has no gasket.
There is no big o-ring like some pumps have and there are no remnants of sealant.
Pictures of the rebuild kit do not show a gasket or o-ring.

Should there be a gasket or sealant or nothing? Wear plate to pump housing.

Should there be sealant on the bottom of the wear plate? Wear plate to lower unit case.
 
The earlier pumps on the 3 cylinder model ( 1968 to 1971 ) used 2 water tubes.-------1972 was the first year for just one brass tube from the pump to the block.-----So the pump on the right is not missing anything if used on a 72 motor !
 
One sent water up to the powerhead, The other one was a return tube, sending water back down to the pump for recirculation when the thermostat was closed. Later models did not have the recirculation feature.
 
Okay, great. They could both work. It also fits with my midsection learnings.
How do I choose which one to use?
What damage or wear should I look for?
 
Flip em over and look for putting or scoring....not usually a problem. From the top, they both look nice.
 
I went with the metal one. It cleaned up nicer. I reassembled the water pump on the lower unit and decided to test it.
I submerged the lower unit such that the water level was above the intake screens (which are clean), but at least an inch below the anti-cavitation plate.
I spun the drive shaft with my drill and got no water flow, I can see the impeller spinning (looking down through the water outlet port).
How deep does the lower unit need to be submerged for the pump to work?
 
Thanks Racerone. Gonna need a deeper sink. Where did you get that info? I couldn't see it in the service manual and I don't have an owners manual.
 
Your local high school may offer an " advanced small engine course "-------Many folks have used night school to gain knowledge.
 
So I built a test tank today out of some random wood I had lying around.
I lined it with a big garbage bag.
The water pump works. Lots of flow.

Racer: I haven't found a course yet. I did get a service manual though. For now, I rely on the manual and you and the other knowledgeable folks on this forum. 20220423_132630[1].jpg20220423_132549[1].jpg
 
Wow! That’s a creative test tank! For next time, go to Wally World & pickup a plastic trash can. It’s much easier to mount the kicker on a sawhorse for initial running & tuning.
 
Thanks. I have garbage cans, but the anti-cav plate was too long. The box is almost a perfect fit so it fills very fast. Garbage bag liner got a leak pretty quick from the skeg.
 
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