Onan 9K generator troubles

J.Wilt

Well-Known Member
Jan 29, 2010
1,083
W. Mich. / Lake Michigan
Boat Info
420 Sundancer 2005
Engines
Cumming 6cta V Drives
Highfield 310 , 20hp Suzuki
Yesterday was oil change day, so I did my normal routine of warming up the generator and it ran just fine. Used the oil pump and pumped out a gallon of oil and changed the oil filter, pumped a gallon of new oil back in and changed the racor fuel filter. I went to start the generator after prime and preheat and it would not turn over just one Klunk like it wanted to turn over, thinking it just needed to be primed more I tried this several times but just one klunk. Then I noticed lots of oil in the pan under the generator, pulled the dipstick and oil poured out of it. Thinking no way did I put too much oil in, I started pumping some of the oil out, it looked funny, I believe that coolant somehow mixed with the oil. Ugggg!
How is the oil leaking out the bottom, cracked block?
Oil filter was tight, no sign of leaking.
 
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Thanks for the reply even if it’s not what I wanted to hear on a Monday morning.
Could be possible but it ran just fine prior to shutting it down.
No sign of water in the oil
 
I have a friend who ran newoil back into his diesel WB - but he forgot to suck out the old oil first. He didn't to turn it over b/c he caught his mistake before trying. It was a simple fix, which he called in a guy to do (had to get the oil out of the cylinders I guess). I'm trying to figure out if pumping oil into the system could cause some sort of communication with the cooling system (?). On the edge of my seat with this one.
 
The oil pump system on these boats is great to use but you have to be careful to turn the right switch for Port/Starboard/Generator.. Always room for human error.
My marnia mechanic is looking into it this week, thinking it could have been desiel fuel mixing, in the meantime grab some popcorn.
 
Good luck...hope it's nothing catastrophic.
 
Mechanic was able to look at the generator today.
First thing he found while taking the heat exchanger off was that it was plugged with pieces of a impeller, I had changed the impeller about four weeks ago and thought I fished out all the pieces, evidently not. He also removed all the lines and back flushed them. I did this also but those little buggers were hiding somewhere else. This is what was keeping the generator from starting. He also looked at the oil and that was clean and free of water or coolant.
Still crossing my fingers and hoping it was just human error and that I must have hit the wrong switch and over filled it with oil. I was very carful but s##t happens.
Will keep you updated if anything else arises.
Thanks for following my adventure.
 
Not sure I get how impeller pieces could prevent the motor from starting. Starting and shutting down bc of an overheat would make sense. But ok. So far so good I guess!
 
Makes no sence to me, when the impeller went out a few weeks ago pieces were plunging the bottom of the heat exchanger but the generator would at least turn over and run for couple seconds. I wish I could be right next to the machanic and ask a how this is possible.
Maybe someone with more experience cold chime in.
 
Here is a discription of what the mechanic did.
Attempted to start generator

Generator cranked slow but started

Generator was not pumping water so we shut it down

Removed impeller and inspected (it was new)

Reinstalled impeller

Removed discharge hose from impeller pump

Started generator (pumping lots of water)

Removed end cap of heat exchanger(was completely plugged with impeller pieces)

Removed impeller pieces from heat exchanger

Removed discharge hose of heat exchanger and back flushed with water

Removed discharge water vented loop and cleaned all the impeller pieces from vent

Reinstalled all the hoses and end caps

Started generator(it was pumping water now)

We loaded tested the battery (it failed the load test)

Cleaned up the oil and inspected for leaks

Could not find any leaks.

I’m again surprised there was that many pieces of impeller, when I replaced the impeller I removed a hand full. As far as the oil, I’m going to chalk that up to human error that I over filled the genny.
Glad it was not worse!
 

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