Hi Steve
Two years ago, I had to replace the starter motor on my 16.5kVA Onan generator, model MDKBR, and it was very difficult to remove the faulty starter motor, owing to access to the bolts being almost impossible. Who designs these things?
To begin with, it looked like it would be necessary to lift the whole unit from the casing to allow access from below. In the event, I jfinally succeeded without doing this. The top bolt wasn't so difficult, as access is easier. I had to grind down an 18mm ring spanner (wrench) on one side, so it sat properly on to the bolt head, as there was insufficient space between the starter housing and the bolt head. There was no access for an open-ended spanner (wrench) without removing the engine. Once loosened a little, I was able to use a socket with various adaptors to undo it.
The bottom bolt was an even greater challenge. I could get an 18mm ring spanner (wrench) to sit half on the bolt head, but couldn't free the bolt by forcing the spanner (wrench) or hitting it with a hammer, as it would just jump off and risk rounding the bolt head.
I finally succeeded by purchasing , which gave me sufficient purchase and leverage (despite not sitting properly and there being only about 5mm of travel) to loosen the bolt a fraction of a turn. In this way, a fraction of a turn at a time, I was able to painstakingly remove the bolt.?
I bought the replacement starter from eBay for a not unreasonable price of 120GBP (160USD).
By the way, my top tip regarding Onan generators is use Jabsco impellers rather than Onan. The Onan impellers repeatedly failed after less than 100 hours. I fitted a Jabsco impeller 3,000 hours ago and it's still going strong. My other tip is to fit a second oil pressure sensor (there is provision for two) and attach an oil pressure gauge to the second one, then if the main one fails, as mine did, you simply swap the cables and you are back in business. One more tip: don't service your generator in the middle of an ocean passage and, if you do, make very sure you put the the seal for the Volvo Penta fuel filter back on the right way up!
Regards
Chris
