I wasn’t sure about the maintenance history of my Onan, so I decided to look at everything, Oil and filter change, new air filter, new plugs, and check the brushes and slip ring. This is a model 5.5BGMFA26105H
I ran the generator for 20 minutes to warm it up, then drained the oil and replaced the filter. I use a WIX 57398 oil filter and refilled it with 3 1/2 qts of 5w30.
The spark plugs are easy to get to. There is a cutout in the top cover for both the front and rear plugs, simply pull the rubber spark plug boot off, and reach in with a spark plug socket to unscrew the plug. Make sure the socket grabs the plug and slowly pull it out
The brushes and slip ring are located behind the air cleaner. After removing the air-cleaner and filter, remove the small plastic cover to gain access to the brushes and slip ring.
Use a pair of needle nose pliers to pull the two spade lug wires from the brush assembly. I taped the ends so they wouldn’t touch anything. They don’t have power on them unless you attempt to start the generator.
The brush assembly is held in by two Torx bolts. Use extreme caution so as not to drop the bolts. I loosened the bolts so they were just ready to come out. I then was able to reach in with needle nose and lift them out one at a time.
There are aftermarket brush and springs available ($25 for two brushes and two springs), or you can buy the block assembly from Onan, I think it runs about $85. Mine looked in good shape, so I cleaned them up and re-used them.
The slip ring can be cleaned and polished. I used a green scrubby pad and started the generator. Make sure the spade lugs are taped up so they don’t short against the generator case. After cleaning, I reinstalled the brush assembly and hooked up the spade lugs.
I installed a new WIX 42362 air filter, buttoned everything up, and ran it for a few minutes to test everything..
New filters, plugs, and good brushes, I know I have a good generator and its up to date on its service. I’m good for another 50 hours.
I’m interested in your choice of 5w30. I have read that 15w40 is the Cummins recommended oil type for these generators, but I’ve also heard of folks using 10W30 in warmer environments. Was there a reason you selected 5w30 for your gen-set?
What is that part called, or is there a part number?
Onan recommends a variety of weights depending on temperature. I usually run 5w30 or 10w30 in all my engines, 5w30 is in the winter months and 10w30 in the summer. 10w30 would probably be a better fit for the generator. However, I have used the generator at -20F, so thats why I put in 5w30. You can see the recommendations in the manual, page 5:
http://1999southwind.com/DOWNLOAD/5500_Onan_Operation_Mmanual.pdf
Thanks once again for the awesome info!
This doesn’t have much to do with the oil changing or anything but we are having trouble with our generator someone removed this little piece that goes inside this fuse port anyone have suggestions
Not sure what you’re talk about? Can you send me a photo?
I have 250 hrs. on my generator and wondered if I should or could use full synthetic oil .