Bad Onan Generator Starter?

Topic: Bad Onan Generator Starter? (Read 912 times) previous topic - next topic

Bad Onan Generator Starter?

December 18, 2019, 01:43:05 pm

My Onan Emerald 6500 LP Gas conversion worked like a champ and started right up until this fall. At that point it became hard to start and I had to crank the starter for longer periods to get it going. Now I think the starter has gone bad. It just clicks. My batteries are fully charged.
Any hints on troubleshooting?
I think I can buy a new starter on ebay for about $30. If I have to replace the starter, do I need to pull it from my coach in order to do so? If so, any hints on how to do that with nothing but hand tools?
Any help will greatly be appreciated.

Re: Bad Onan Generator Starter?

Reply #1 – December 18, 2019, 01:49:26 pm

Before condemning the starter, verify voltage at the large lug on the generator to generator clean metal housing. If it drops below 12.0 VDC with batteries in good condition, yes it could be a bad starter (excessive draw), but could also be a bad connection (positive or more likely on the ground side).

If low voltage when cranking, use a jumper cable from clean metal on the generator to clean metal anywhere on the coach frame. OE ground path was through the slide tray bearings-- NOT a good ground path. Pretty easy to run a permanent 2 gauge wire from generator to coach frame member.

And, if starter issue is resolved but long cranking times, my $$ is on a clogged on-generator regulator. Been there, done that, and overhauled the regulator and converted from liquid LP to high pressure vapor LP to minimize contaminants in the propane from clogging the regulator again.

Re: Bad Onan Generator Starter?

Reply #2 – December 18, 2019, 01:55:29 pm

Thanks Brett. I'll do some checking.

Re: Bad Onan Generator Starter?

Reply #3 – December 18, 2019, 07:01:17 pm

I am sitting here thinking about my Onan starter. It "crapped" out because the little plastic cage that is supposed to push the gear back out of engagement broke and the spring worked its way up to the end of the starter so the gear only backed out of engagement after awhile.
Yes, you will have to pull the generator out a bit in order to change starters. Unfortunately the starter is inboard of the generator housing.
Disconnect the battery, both at the battery and at the control board on the generator.
Remove the muffler from the engine.
Remove the safety bolt that has the bolt head directly rearward of the driver's front tire (3/4"socket)
Open the electrical box and label the wires BEFORE disconnecting.
Turn off propane at tank. Then disconnect propane line from regulator at the generator.
Remove compartment door + hinge.
Pull generator outward from compartment.
Disconnect wires to starter & ground.
Replace starter BUT CHECK GENERATOR END BEARING FIRST.
IF YOU FEEL IT IS NECESSARY TO REPLACE THE BEARING THEN FIRST PULL THE BRUSHES BACK AWAY FROM ARMATURE AND WIRE THEM IN PLACE. remove the housing and use a bearing puller or a socket and a hammer. I got my bearing from a bearing supply house for around $7. Onan was around $16 for the same thing.
Reverse the assembly procedure.
If you cannot start the generator from the remotes or on the generator itself then your circuit board is toast and you will have to procure another one from Dinasaur boards (or something like that--$116)

Re: Bad Onan Generator Starter?

Reply #4 – December 18, 2019, 07:32:52 pm

Thanks Nitehawk. I hope Brett's suggestions prevent me from having to do this but your step-by-step instruction will be a great help if/when I need to do it.

Re: Bad Onan Generator Starter?

Reply #5 – January 07, 2020, 03:37:03 pm

I've been plugging away at this job as time and weather allows and am getting close to pulling the generator. It may take a day or longer for me to complete once the generator is pulled out. I can't run the refrigerator on gas if it's shut off at the tank. Is there a work around? Any thoughts?

Re: Bad Onan Generator Starter?

Reply #6 – January 07, 2020, 03:41:22 pm

Is your generator LIQUID or vapor LP? Many of that vintage had the generator on a separate (liquid) tap-- not related to the vapor tap for house LP appliances. If this is what you have, merely close the liquid valve on the tank, start the generator to run it out of fuel and you are good to go.

Check your propane tank and let us know.

Re: Bad Onan Generator Starter?

Reply #7 – January 07, 2020, 03:51:23 pm

You can turn off the gas remove the line at the generator and install a plug in the line and then turn the gas back on.

Re: Bad Onan Generator Starter?

Reply #8 – January 07, 2020, 04:14:41 pm

Thanks guys. Brett, here are a couple photos of the tank....

Re: Bad Onan Generator Starter?

Reply #9 – January 07, 2020, 04:19:42 pm

Can't really tell from the photo.

Is the regulator in the lower left of the picture for the generator? If so, is it fed by the liquid or vapor port.

Re: Bad Onan Generator Starter?

Reply #10 – January 07, 2020, 04:28:06 pm

Quote from: wolfe10 – January 07, 2020, 04:19:42 pm

Can't really tell from the photo.

Is the regulator in the lower left of the picture for the generator? If so, is it fed by the liquid or vapor port.

It looks like the liquid valve has nothing coming out of it.

Re: Bad Onan Generator Starter?

Reply #11 – January 07, 2020, 04:34:02 pm

Ya, blowing up the picture on my computer instead of a smaller device-- I think you are correct.

So where does the vapor line "T" off to the generator regulator?

Re: Bad Onan Generator Starter?

Reply #12 – January 07, 2020, 04:42:54 pm

I was told that the 2 valves on the right side were for liquid and for vapor, the lower being the liquid but I really know nothing about what goes where.

Re: Bad Onan Generator Starter?

Reply #13 – January 07, 2020, 04:47:40 pm

I think this photo will help...

Re: Bad Onan Generator Starter?

Reply #14 – January 07, 2020, 05:07:30 pm

The two valves on the tank WILL be labeled. You can clearly see "Vapor" on the top one and guarantee the bottom one says Liquid.

The question is where does the generator feed tie in to the vapor port-- assume before the house regulator, but not clear in the photo. Follow it with your hand.

Re: Bad Onan Generator Starter?

Reply #15 – January 07, 2020, 05:25:52 pm

Quote from: wolfe10 – January 07, 2020, 05:07:30 pm

The two valves on the tank WILL be labeled. You can clearly see "Vapor" on the top one and guarantee the bottom one says Liquid.

The question is where does the generator feed tie in to the vapor port-- assume before the house regulator, but not clear in the photo. Follow it with your hand.

You are correct Brett. There is a line coming off the vapor line before (what I now know is) the house regulator on the right side of the tank. That line goes to the regulator on the left side of the tank and then on to the generator.

Re: Bad Onan Generator Starter?

Reply #16 – January 07, 2020, 05:32:10 pm

Should be able to find a cap at any propane store.

Turn off the vapor port. Since the generator is not operating, light the stove to remove all pressure.

Remove that line and cap it off while doing the repair. If it is cool outside and your repair will last a half day or less, I would not worry with it-- refrigerator won't heat up that fast in the winter.

Re: Bad Onan Generator Starter?

Reply #17 – January 07, 2020, 05:34:04 pm

OK. It all makes sense to me now. I just need to get a plug for the line (as Ron the red tractor said) where it plugs into the generator.
Is this plug available say, at the local Ace Hardware?

Re: Bad Onan Generator Starter?

Reply #18 – January 07, 2020, 05:39:43 pm

More likely at a propane store.

And, suggest bleeding off pressure before doing this.

Re: Bad Onan Generator Starter?

Reply #19 – January 07, 2020, 05:45:27 pm

Thanks Brett and everyone. While I have the generator out I'm also going address and attempt to correct any problems I have with regulators and gas flow -- and I'm also going to replace the rear spark plug that is impossible to get at.

Re: Bad Onan Generator Starter?

Reply #20 – January 07, 2020, 05:54:51 pm

If (actually big IF) you have the in-generator Impco J regulator, be sure you get the HIGH TEMP gasket set:
Century Fuel Products | Generator Conversion Kits | Forklift Parts

With the regulator in the propane tank compartment, don't really know what other regulator you have or if you even have one in the generator itself. Our 1993 with the same propane generator only had the in-generator regulator and was originally a liquid only.

Re: Bad Onan Generator Starter?

Reply #21 – January 07, 2020, 06:08:37 pm

Brett, this is what I have...

Re: Bad Onan Generator Starter?

Reply #22 – January 07, 2020, 06:14:50 pm

SOOOO, two regulators for the generator, one in propane locker, one at the generator.

Looks like either would be easy to work on without removing the generator.

Much easier than the ones that are inside the generator.

Re: Bad Onan Generator Starter?

Reply #23 – January 07, 2020, 08:10:21 pm

I found the regulator in the propane tank compartment to be the one that failed on me. This was also the one that supplied the propane to the generator regulator.

Re: Bad Onan Generator Starter?

Reply #24 – January 07, 2020, 08:16:54 pm

Quote from: wolfe10 – January 07, 2020, 05:39:43 pm

More likely at a propane store.

And, suggest bleeding off pressure before doing this.

These are standard flare or pipe plugs and are less expensive at the big box store, plumbing supply store or on line. You just gotta match what you got.

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