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Onan 45.0EM Starter Ring Gear


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  #1  
Old 11-13-2017, 10:20:44 PM
mazdaboi mazdaboi is offline
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Default Onan 45.0EM Starter Ring Gear

All,

A few months ago, I posted about buying a 45.0EM for use to power my hobby needs, and for a backup generator for the household. The road to get to where I'm at has been a bit long, and I have not reached my destination yet, for a variety of reasons. One thing after another....

The latest is that the starter ring gear has came off the flywheel. I'm assuming that the ring gear is heat fitted to the flywheel, as it would be on a standard Ford flywheel. I've not pulled the engine yet... Pulled the starter to confirm the diagnosis. Was a bit frustrated, so I let it be for a week. But, I obviously need a new ring gear.

My question is this... Does Onan use a standard sized Ford ring gear, or is it specific to Onan? I looked in one of the parts manuals and found part # 104-0723 seems to be the Onan #. But if it's a standard Ford sized part, might be easier to find it from a standard parts house. I'd like to go ahead and order one and get it shipped in so I can perhaps separate the head and engine this weekend, and get the ring gear fitted.

Next hurdle will be realigning the rotor and crankshaft.. Better start researching that procedure now, while I wait for a ring gear to be ordered and arrive.

Appreciate any info in advance.

Thanks!
Brad
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  #2  
Old 11-13-2017, 10:48:04 PM
Birken Vogt Birken Vogt is offline
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Default Re: Onan 45.0EM Starter Ring Gear

Your safest bet will probably be to get one from a Ford Power Products (industrial engines) dealer. Onan will have it but it will be expensive. Ford might be pricey also but at least you will know it is right. Chances are the auto parts store will have it also but you will need to remove the old one and bring it in and possibly wait for a replacement.
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Old 11-14-2017, 07:56:15 AM
mazdaboi mazdaboi is offline
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Default Re: Onan 45.0EM Starter Ring Gear

Thank you for the input.

I will get it pulled apart this weekend, and get the ring gear and flywheel out. Will examine the ring gear and compare it to the stock Ford options out there....

I have been looking for the Onan part number I mentioned previously.... I'm finding it listed as discontinued on every site I've found it referenced, and no cross referenced replacement.

*Fingers crossed* Really hope a Ford part will match up. This genny has been one trial after another. Just worried about what issue I'll run into after the ring gear is repaired.

Thanks,
Brad
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  #4  
Old 11-14-2017, 11:18:31 AM
Birken Vogt Birken Vogt is offline
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Default Re: Onan 45.0EM Starter Ring Gear

Maybe I made an inaccurate statement about Onan/Cummins having one available.

But I have bought lots of parts from Cummins that showed on all the web sites as NLA. On the other hand I have also been surprised that something in recent production was listed as obsolete. Plus the prices are all over the map.

Ring gears are something there has been pretty good aftermarket support for. A friend of mine had a GM Bedford engine which needed a ring gear. He looked all over and wound up at a clutch shop. They had a ring gear for some kind of Cat engine with the right teeth but quite a bit smaller I.D. They turned the flywheel on a lathe to make it fit and it worked great.

You should not have to go to that length on a common Ford engine.

At the absolute worst case, get it off by heat and not by chisel. Then if you absolutely cannot find one you can flip it over and/or turn it so the starter lands on good spots. Engines usually stop at the same spot when they come to rest so there will be chewed spots and spots that are not chewed.
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  #5  
Old 11-14-2017, 01:21:58 PM
Oldpart Oldpart is offline
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Default Re: Onan 45.0EM Starter Ring Gear

If the ring gear simply came off because of too little shrink fit interference it could probably be reused by pressing it back on the flywheel using loctite sleeve retainer. The stuff is incredible. You could not heat the ring gear to drop it on but you could press it on after cleaning both parts perfectly. If the ring is junk - well that's another matter.
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  #6  
Old 11-14-2017, 05:05:51 PM
Troll Troll is offline
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Default Re: Onan 45.0EM Starter Ring Gear

Eight evenly spaced tack welds using 309L stainless rod will retain a ring gear that is not salvageable by other means also. Rather permanent however.
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Old 11-14-2017, 06:25:41 PM
Power Power is offline
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Default Re: Onan 45.0EM Starter Ring Gear

Quote:
Originally Posted by Oldpart View Post
If the ring gear simply came off because of too little shrink fit interference it could probably be reused by pressing it back on the flywheel using loctite sleeve retainer. The stuff is incredible. You could not heat the ring gear to drop it on but you could press it on after cleaning both parts perfectly. If the ring is junk - well that's another matter.
I agree. flip it, clean up contact surfaces and use locktite bearing lock or sleeve retainer. Last resort is tack welds. A new ring gear may not be the answer. If the existing ring gear had been slipping before it fell off, the flywheel contact surfaces may have been milled undersize, and the new ring gear will slip.
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Old 11-14-2017, 07:36:41 PM
Gunny Gunny is offline
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Default Re: Onan 45.0EM Starter Ring Gear

If my memory is correct, that is a standard Ford part, nothing special about it.

Can't flip it over, teeth on the drive side are beveled.

Have never seen one slip, usually have a tooth or teeth missing or damaged. Consider a new starter to go with a new ring gear.

Pretty easy to align, can take 2 bolts a little longer than the original bolts, cut the heads off and grind a bevel. Don't run them all the way in so you can grip them and screw them back out when the others are started. Pretty easy to do, go carefully and you shouldn't need much force.

I've never used any adhesive to hold it together. Just heat it barely red and drop it on, might need to tap it a little. Be sure to get the bevel end right. Take the old one off by grinding through it.

If slipping, you could do some tack welds evenly spaced. Could grind the welds back off if you need to take it off. Not how I'd do it but if that's what you have to do....
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  #9  
Old 11-15-2017, 07:51:38 AM
mazdaboi mazdaboi is offline
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Default Re: Onan 45.0EM Starter Ring Gear

Thank you all very much for the additional advice. I've now got a few options to look at, depending on what I find when I pull the engine.

This happened a couple weeks ago, when I was trying to get the gas regulator adjusted. The last time I fired it up, the starter spun up, but the engine did not. Tapped the starter to make sure the throw out wasn't sticking. No change. Figured I hit a bad spot on the ring gear, so I turned the engine over by hand, then tried again. This time, it sounded like a metal hula hoop in a tin can. Pulled the starter to confirm what my ears had told me... Ring gear had came off.

The real question is why. It has never sounded like it was slipping previously. Best case, the ring gear broke somehow and a replacement ring gear will get me back to where I was. Worst case, if the flywheel mating surface is somehow not the exact diameter it's supposed to be, then I guess I'll be in the market for a new flywheel.

So, yeah.... I need to get the engine hoist up to the barn tonight and start to pull the engine. Can't order parts until I know what I'm dealing with. Thanks to you guys, I have a few options to explore, depending upon what I see.

I'll let you know what I find.

Thanks!
Brad
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  #10  
Old 11-15-2017, 06:16:07 PM
Gunny Gunny is offline
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Default Re: Onan 45.0EM Starter Ring Gear

I never pulled the engine in the couple of dozen I've done through the years.

Slide the generator back about 12 to 18", after unbolting from the engine and you';; have plenty of room to get the flywheel out.

There was a campaign in the mid 90's to replace the bolts on thew flex plate, made up a jig with some wheels (casters) and most of the time was a quick and easy job. Unless the installing sparktrician did something wild, that happened too often.

Really an easy job in the overall scope of things.
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  #11  
Old 11-18-2017, 06:40:46 PM
mazdaboi mazdaboi is offline
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Default Re: Onan 45.0EM Starter Ring Gear

Worked on the generator some today.

Found that the cause of all this is that the ring gear broke. I think that's the best case scenario, and means that the flywheel itself should be fine. I counted the teeth while I was at it, and netted 184 total. That's the standard Ford ring gear tooth count. Sounds promising. Still need to measure the ID, to be absolutely sure.

Started working on preparing to separate the generator head from the engine. Was able to loosen all the bolts holding the head to the flywheel housing, and got all the bolts holding the drive plate to the flywheel loose.

I have a question, before I proceed further. Please forgive me for the basic question... First large generator teardown... When I remove the bolts from the drive plate, and start to separate the engine and head, the rotor is going to be unsupported on the engine side. Do I need to support the rotor somehow, so it won't rest on the stator?

Thanks,
Brad
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  #12  
Old 11-18-2017, 07:04:00 PM
pegasuspinto pegasuspinto is offline
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Default Re: Onan 45.0EM Starter Ring Gear

It's just a standard ring gear. I've got them from the auto parts store.

Looks like PN# BK-6003035 from Napa, $26. Should be able to get them from any auto parts store.

Just let the rotor rest, but you should make efforts to not let it get too far off horizontal, like having it roll off the supports, or it might try to slip out of the can, which could be bad.

You won't want or need to get the ring gear red to get it on. I've got one to slip on with a pair of heat guns. Probably never got it over 400 degrees.
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Old 11-18-2017, 08:17:34 PM
Birken Vogt Birken Vogt is offline
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Default Re: Onan 45.0EM Starter Ring Gear

Conventional way to get a ring gear that size on is to stick it in a standard oven for a while. I think it will fit.
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Old 11-18-2017, 08:33:50 PM
mazdaboi mazdaboi is offline
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Default Re: Onan 45.0EM Starter Ring Gear

Cool! Thank you for the input.

I've got a ring gear ordered, as well as a rear main seal. It seemed to be leaking some, so I figured I better replace the seal while in there. Should be in on Wednesday.

Appreciate the advice on the rotor!

I'm going to try Gunny's advice on sliding the head back from the engine, instead of pulling the engine. I'll make sure that the head stays horizontal, as you mentioned.
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  #15  
Old 11-19-2017, 12:38:37 AM
suntreemcanic suntreemcanic is offline
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Default Re: Onan 45.0EM Starter Ring Gear

As stated previously do not heat the ring gear till it is red. Heat evenly with a torch till when you spit on it the spit bounces off. Quickly lower it onto the flywheel. It will cool real fast once it touches the flywheel (shrink) so make sure it seats all the way around.
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Old 11-19-2017, 01:00:39 AM
pegasuspinto pegasuspinto is offline
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Default Re: Onan 45.0EM Starter Ring Gear

Keep in mind the rotor/stator are going to be REAL DANG HEAVY. Maybe..800 pounds if I had to guess. Not an epic weight but plenty to smash fingers and toes, and more then you can wrestle around if your support system gives way. I've used a small car jacks and plenty of blocks of wood, or if you had a hoist that would work well too.
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Old 11-19-2017, 11:33:09 AM
mazdaboi mazdaboi is offline
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Default Re: Onan 45.0EM Starter Ring Gear

I'll make sure to keep the heating under control, and not overdo it. I'd think that if one would overheat too much, it could cause problems with the temper.

As far as supporting the head... I was planning in putting a sling around the head on both sides, and using my engine hoist to raise it a little until it just barely raises off its mounts. I've got some blocks of 4x4 and 2x4 laying around, so I'll put some mini cribbing under it, just in case.

Thank you all for the advice.
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Old 11-19-2017, 01:55:18 PM
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Default Re: Onan 45.0EM Starter Ring Gear

In 60+ years working on vehicles, I have come across ring gears with teeth milled out, 3 that came off flywheel, but never one that broke. Since you do not want to do a repeat performance, suggest while you have everything apart, check starter pinion, etc. to see if you can determine what caused it to break. Maybe a bolt or piece of metal got in teeth?
Examine where it broke, hopefully you find a flaw in ring gear that caused break.

I second the oven method.
I set the oven to 550 degrees and carried ring gear out to engine with a piece of 2x4 through the center. Quickly put it on flywheel, and used 2x4 and hammer to seat ring gear.
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Old 11-25-2017, 01:57:16 PM
mazdaboi mazdaboi is offline
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Default Re: Onan 45.0EM Starter Ring Gear

Thanks for the input. I will definitely look over everything, to see if I can find a cause for the failure.

I'll also use the recommended oven method for heating the ring gear. The other option was to take the flywheel and ring gear to a buddy's and have him use a torch to heat it and put it in place. I'd think an oven would heat the gear more evenly, though.

Working on the project more today...

I've removed the drive plate to flywheel bolts, the head to flywheel housing bolts, and the head to skid mounting point bolts. When I tried to lift the head some, to see if it was loose, it wouldn't budge.

I found the long through-bolts from the end bell side to the flywheel housing. In one post here on the forum, I found someone else asking whether to remove them. The reply on that thread was a yes, as that individual was trying to separate the stator and rotor. In my case, where I'm trying to keep the head as intact as possible, I'm trying to see if there's a way to separate the engine and the flywheel housing instead of pulling the head off the flywheel housing.

I'm taking this a bit slow... I've never wrenched on a large generator before. Most of my knuckle busting is done on vehicles. Doing more reading on the forums and such before making the next step.

I didn't like the way the sling was sitting around the head anyway, so stepping back for a few hours gives me a chance to find a better way to sling up the head.

Thanks,
Brad
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Old 11-25-2017, 02:11:21 PM
Troll Troll is offline
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Default Re: Onan 45.0EM Starter Ring Gear

I use an engine leveling adjuster. This hangs from the hook on a cherry picker type floor Crane and you can adjust it for an aft for center of gravity. From the hooks on this at the ends I use two straps around the generator section one of the front of the generator section, one at the back. Very easy to find level with this.
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