Raw Water pump

[tonyiiiafl]

2 moths ago I replaced both raw water pumps (Gen V Merc 7.4 Carb) they have teh fuel pump mounted on top with new units. The starboard pumped “Ok” (No over heating) Port pumped a lot! Boat has sat for 5 weeks, and I was getting ready to run it up the river for storage. Port started and pumped fine. Starboard started and would NOT pump water! I took off hoses and primed, filled heat exchanger with raw water, noting at all. A real chore removing this one, but tomorrow out it comes and a rebuild kit goes in. Just disappointed that a new pump (came assembled) just quit pumping. OK, done with the rant!

[Viper]

Tony, try chopping the throttle first to see if she'll start pumping. The problem with new pump assemblies is they come with the impellers installed and you could end up buying a pump with an impeller that has already taken a set from sitting on the warehouse shelf for so long. It could have been there for years by the time it got to you.

[tonyiiiafl]

I stabbed the throttle a few times, nothing. I had a bad feeling when it was pumping water when installed, but not a great pump. So you are probably correct in that it may have had a set to it. I will see tomorrow.

[tonyiiiafl]

Pulled the pump out today (I am getting GREAT at this!) Never saw this before but the hub of the impeller had broken, so the shaft was spinning inside the impeller, and that is why it was not turning. NEW Genuine Quick Silver kit (the BEST China has to offer!) and now she is a pumping! GREAT ride to winter storage and this new enclosure is great! Clear as a bell! HOWEVER, even though I had a padding on top of the engine, I got pretty cut up. OH well, she was brought up the river for haul out. FINISHED WITH ENGINES 2021!

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[bud37]

That could have been a one off, but, I have never liked those plastic pump bodies with the newer style impellers. Just an anecdote that I found....I was going thru impellers on the generator, it had a plastic pump.....so I changed the pump to brass and the problem stopped......I can't explain and guessing well.....

It would be nice to see some engineering notes on the testing that was done before production. My choice would be the metal pumps if there was a choice........

[Viper]

Tony, you should be okay for now considering the pumps are new but don't forget to change the oil in the pumps every time you have them off to replace an impeller.

[tonyiiiafl]

I learned about changing the pump grease the hard way. When I got the boat, a cam sheared on the raw water pump. I was replacing it and the 90W was like 10W oil, thin and washed out. I now get the raw water pumps with 2 fill points and every spring, I drain and replace with new 90W. Pasr of my preseason checklist.