Community Forums

pjtatro · 06-25-2014, 07:31 PM

I have an Onan 7500 diesel generator and when I was checking the oil I noticed I have diesel in my oil and the oil is way over the save zone on the dipstick. I am wondering where to start troubleshooting this issue. I was going to start by draining and replacing the oil, running the gen and seeing if the issue repeats itself. Anyone else have this issue and how did you resolve it?

Thanks,

Pete

Skip426 · 06-26-2014, 12:23 AM

Sorry your here with problems.
Question .
Any idea how long the fuel took to accumulate in the oil ?
The reason I ask , is the only way for the fuel to enter the oil pan would be for the fuel injector (s ) to leak and the fuel to seep past the piston rings.
Not really a DIY , diagnose or repair.
If after the oil & filter change the gen set runs smoothly with no black smoke from the exhaust, I would add a high quality diesel fuel injector cleaner to the fuel tank and run the gen set for an extended period of time.
Then check the oil level every time before you start the set back up.
If you see a lot of black smoke and it doesn't run smoothly , shut the set down and seek out a service facility. You could wash down a cylinder or put a hole in a piston.

NHRA225 · 06-26-2014, 05:42 AM

Year make and Model would be helpful to offer suggestions.

pjtatro · 06-26-2014, 04:06 PM

Thanks for the replies. The Model is an Onan 7.5HDKAJ11502D. The MH is a 1999 Fleetwood Discovery 36T, so I assume the generator is a 1999 ish model.

Thanks for your help. Headed out to change the oil and filter now.

pjtatro · 06-26-2014, 07:38 PM

OK, please never mind this post, I was wrong, gen is fine. Diesel leak from fuel line, no diesel in crank case when I drained it. Sorry for the confusion.