Onan 6.5 Generator - Loss of Prime ???

Natchamp · Post by **Natchamp** » Fri Jan 13, 2012 8:53 am

I'm wondering if anyone else has come across this problem. I just finished installing my genset back into my boat. The first time I started it, everything was fine. It runs excellent and was flowing good water through the exhaust. I'm using one of those "toilet plunger" looking things for supplying water to the seacock from under the boat.

The second time I started it I wasn't getting any water out of the exhaust. I immediately shut it down as I don't want to burn up the pump impeller. I verified the water supply was good and tried again. Same thing, no water out the exhaust.

Any ideas why this would happen and/or how to fix?

g36 · Post by **g36** » Fri Jan 13, 2012 9:41 am

it could be that while the boat is sitting on the hard and after you ran the gen, and let it sit it drained all the water back out of the intake.there would remain some water you assume in the impeller housing. that should take care of it running dry on start up but if the gasket or the impeller housing has a leak in it and it has dried up. when you restart the gen again it being dry could have already damaged your new impeller. i would open it up again and take a look. i know you just installed it but verify it again. then check for hose clamps, gasket on the housing for any thing loose to allow an air leak. on the hard to prevent the water that has been sucked up the intake hose from draining all back out i would shut the engine seacocks immedaitely after running by doing this you have assured that the remaing water in the intake hose will be there then when you want to hook up your toilet plunger again then when you turn it on and open your seacocks you should be good to go without the time it takes for the impeller to pick up the water again. anytime you haul a boat i follow doing this also then when your back in your good to go. i dont haul mine for the winter so of course this would not be true to do when it could freeze. just my thoughts

Natchamp · Post by **Natchamp** » Fri Jan 13, 2012 11:11 am

That idea of closing the seacock sounds like a good one, Thanks!

alexander38 · Post by **alexander38** » Sat Jan 14, 2012 4:19 am

after you've check out the pump for damage make sure the belt is adjusted right they can slip from time to time and is hard to see if all the covers are on..

lakeguy72 · Post by **lakeguy72** » Sat Jan 14, 2012 10:39 pm

Check the set screw on the raw water pump pulley. Mine loosened up last year. The pulley will turn but not engage the impeller.

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Onan 6.5 Generator - Loss of Prime ???

Onan 6.5 Generator - Loss of Prime ???

Onan loses prime