Onan Generator Help
 

Onan 5500 diesel generator...cranks but won't fire. Let off the switch and it dies. Just changed air filter, fuel filter, and oil and filter for regular Winter service.

If I make it crank until it times out it spits out code 32...which is low battery during cranking. Batteries are at 13.66 volts. Even started the coach and let it run and tried it as instructed in the manual...no better.

I know there are some RV service guys on here...any help would be great!

Re: Onan Generator Help
 

Tim, Rich Beibel is one of many ONAN go to guys on this forum. He is very helpful. Perhaps you could PM him if he doesn’t see this post....

Re: Onan Generator Help
 

I had a similar problem with my Onan 7500 last year. Mine is a gas version. My problem was that the drive belt broke and the generator would not rotate with the engine. Onan's have to detect AC voltage to keep the engine running after you release the start switch. It may be the belt, brushes, or anything that doesn't let the generator produce AC.
Dan

Re: Onan Generator Help
 

PM sent with some info Tim.....

I reread your above post....

You may have worn brushes......no output....won't run....

Brushes are on left side under a cover......

Re: Onan Generator Help
 

And I assume taking the cover off will show me if the belt is broken as well...no rotation.

Didn't get the PM yet...maybe wrong Tim?

Appreciate the help...

Re: Onan Generator Help
 

I’ve never seen a belt break on a 5500 diesel.
If it has no output it will shut right down.
Put a voltmeter on the machines AC output wires as close to the machine as you can get. Terminal strip at rear left upper corner under cover is AC output.
If it starts even momentarily you should see AC output.
If no output the brushes are the first thing to check next.

Top cover off allows you to see the belt. It’s at the back of the machine, look straight down.

Brushes are the same ones used on gas machines. They wear or fail regularly. If they did fail you will need to sand the rotors slip rings for sure. A piece of sand paper taped to a wooden stick works well. I use paint stirs and cut strips to fit.
If brushes are ok it gets more complicated.

Re: Onan Generator Help
 

Well I'm your first then...belt is broken. Based on the way it suddenly quit, I suspected voltdr was probably right. Took the brush cover off and cranked it, fan did not spin. Reached in to the pulley on the generator input and there was no belt. I was able to feel around and grab the belt and remove it. Now I have the part number. Getting the back panel off and the belt on will be a treat in my coach...

Thanks for both your help...

Re: Onan Generator Help
 

Yes that’s a first.
It’s a pretty HD belt.
Check to make sure nothing dropped down in there and caused the failure.
On some machines the battery charging voltage regulator/rectifier is mounted above the belt. The mount breaks from vibration.

They are not fun to work on. Very compact units and very busy inside.

Just about every machine I repair in MH’s has to come out to fix. Very little access.

If you can fix it without pulling it out that’s a plus.