Flybull
Senior Member
Following closely as I just had a genny problem on my 15kw Onan (Cummins)...
A week ago I shut it down after noticing less water output and steam flashing indicating higher exhaust temps (at least in my mind). I pulled the intake pump and found the impeller in bad shape as anticipated.
I had a spare impeller from PO as this is a new-to-me boat, and I changed it out and fired up to normal operation. Being dockside on shore power, I switched the load gradually to genny and let it test run with full loads for about 20 minutes and all seemed normal. As a side note... although this Onan has oil pres., temp., and DC volt guages on both the genset in the ER and on remote panel in main AC/DC panel, the temp guages do not work on either.
So the other day, we left for an all day cruise and all was working fine as usual, both ac's running, full size fridge, ice maker, water heater... and for about 7 hours nothing unusual. I think I looked over the port side a thousand times watching water/exhaust flow...
At some point, in the last 45 minutes of the cruise, she stopped. I was not aware until I went down below while underway and noticed no ac working.
I have yet to be able to start any troubleshooting at all due to having company at the time and started work the next day. Thursday is my day off so will start checking into things, and am glad this thread started as there are some great ideas here. I haven't even tried a restart, as I haven't had a chance to break down the sound box for even a 1st step visual check of things.
Sorry for any derail/hijack of your thread, OP... glad there's so much knowledge here to tap into. I have no problem starting a separate thread after initial observations if that is the proper thing to do.
Thanks, and good luck getting to the bottom of it OP...
UPDATE:
Finally was able to get to the genny issue on Thursday. The fault breaker was tripped, which trips for water temp, oil temp, oil press. Pulled the sound shield box and removed inlet side hose to water pump to inspect impeller without pulling... it looked really good after bumping start switch a few times.
What I found upon restarting the generator with no load was that the intake hose from the strainer was collapsing from the suction. Strainer was clean. The hose felt very soft and was restricting flow to the pump.
After replacing the intake hose with new, she's throwing water out of the exhaust at a higher rate than I've ever seen since owning this boat, and we were out all day yesterday at heavy load with no issues.