Onan Impeller

[rossjo]

well the bits and pieces of broken off impeller have to go somewhere correct? do they exit the system of do they get stuck somewhere?

They usually get stuck and plug something up.

[aaronbocknek]

Now that is a interesting solution. I shall keep that in mind for future use. Thanks for the information.

the initial problem began when i noticed the genset 'smelled' hot, the exhaust 'sounded' way too loud, and very little water was flowing from the exhaust. it just didn't 'sound' right and it was really laboring. when i looked at the water pump pulley assembly, i discovered a bolt had worked it's way loose and caused the pump to 'rotate, rotate, stop. rotate, rotate, stop'. that's what caused the initial shredding of the impeller in addition, there was evidence of zebra muscle shells in the impeller housing. somehow, they sneaked through my strainer. all 6 blades of the impeller were destroyed but i managed to 'rebuild' the remains, including several small pieces. non made it into the rest of the cooling system thank goodness. once the offending bolt was tightened and the impeller and wear plate installed, i still was not getting sufficient water flow out the exhaust. thats when i ran into my mechanic friend and the first words out of his mouth were 'THERMOSTATS'. i must admit, i was in awe at how small they are and how great the 'acid flush' worked. the more it is run, especially with a load on it, the better it sounds because crud does not build up in the manifolds. he said this is the biggest kiss of death to gensets..... the lack of a biweekly runup. when the boat is put away for the winter, i also bump the impellers on the engines and genset twice a month so they do not 'set up' during the winter layup.
the marykate on and off acid flush is also a good yearly thing to do especially on the genset and a/c systems since the water systems on these units are smaller than the engines and buildup of 'critters' is more prevalent in them.
so far, so good.

[sluggo]

steve O I have a similiar problem, and we can't find the solution, other then I disconnect the intake hose, and spray a soapy water mixture into the intake to the genny. Reconnect the hoses and it seems to work fine. it is a PIA, but it works. Now if I run the genny after it has picked up and is 'making water' and run the boat with the genny on, everything is fine. If I run the boat, stop, and then try the genny, I will have to do the soapy water thingy

[rickalan35]

Earlier this season, as I believe I mentioned in this forum, my relatively new (6 mo) Onan impeller was spinning on it's core like G36 suggested above.

Our mechanic noted that the "new" impellers weren't always as well made as their predecessors had been. Something about where they were being made, if I recall.