Went to start the Onan generator and it went Whine, whine, whine.
Removed starter and was surprised to find that the gear was plastic and shot to hell.

Would suggest you may want to add this to your list of Preventive Maint chores for those that have Onan Emerald III generators. Easy to replace and found aftermarket starter on Ebay for $67.00

Onan has appx 400 Hour run time.

I would closely inspect the ring gear for burrs and roughness, and consider some fine filing.

How is the timing? Too much advance can strain a starter, and the weakest part fails.

Do you know whether anyone has ever used starter fluid? That is a starter buster.

I don't know your Onan, but any dampness on a distributor cap or its counterpart can cause kickback on startup.

Comparing another starter to the failed part. It looks like the spring broke that sends the bendix back after start up.



Which came first...

Did the starter bendix return spring break causing the gear to get stuck, overspin and strip... Or, did the starter stay electrically engaged during cranking?

Normally, if the starter was hung up and the spring was still there beforehand, I would have expected to see more wear on the end of the bendix. Instead, I see starter gear mashing on the end and it stripped out on the inside of the gear.

When something fails, you try to figure out what caused the failure. If the starter failed from a broken spring then it's understandable and you move on. In this case, it appears to be just that.

If the starter failed from it being hung up then you need to address that issue. A hung up starter could be caused by the starter motor switch sticking. If that happened then the starter would have kept cranking after startup.

Being a tractor trailer truck mechanic, everything smaller looks "Light Duty" to me. That little bendix return spring would give me pause...

I would strongly suggest following Bill H's advise

quote:

I would closely inspect the ring gear for burrs and roughness, and consider some fine filing.

Thanks for sharing your experience Ray!

Back in our Cruise America rental days, they always told us to hold the starter button down until the engine is running smoothly. They said it wouldn't hurt the starter at all and this is how Onans are supposed to be started. Didn't make sense then, and doesn't now.

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Removed starter and was surprised to find that the gear was plastic and shot to hell.

It is probably a glass impregnated nylon or ABS composite. It is also probably a good design by the engineers as it is self lubricating and sacrificial so as not to tear up your ring gear. Check with Onan, but it was probably designed to be left un-lubricated. Lubrication may cause a premature failure of a composite part.

I'm just sayin... "plastic" doesn't always mean bad.

quote:

Originally posted by Bill N.Y.:
Comparing another starter to the failed part. It looks like the spring broke that sends the bendix back after start up.



Which came first...

Did the starter bendix return spring break causing the gear to get stuck, overspin and strip... Or, did the starter stay electrically engaged during cranking?

Normally, if the starter was hung up and the spring was still there beforehand, I would have expected to see more wear on the end of the bendix. Instead, I see starter gear mashing on the end and it stripped out on the inside of the gear.

When something fails, you try to figure out what caused the failure. If the starter failed from a broken spring then it's understandable and you move on. In this case, it appears to be just that.

If the starter failed from it being hung up then you need to address that issue. A hung up starter could be caused by the starter motor switch sticking. If that happened then the starter would have kept cranking after startup.

I don't think so. As long as the engine is turning faster than cranking speed, the spiral grooves on the shaft should force the pinion back out of engagement, regardless of the starter turning or not.

quote:

Being a tractor trailer truck mechanic, everything smaller looks "Light Duty" to me. That little bendix return spring would give me pause...

Being a Kohler fiddler, that Onan starter drive looks incredibly "light duty" to me, too.

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I would strongly suggest following Bill H's advise

quote:

I would closely inspect the ring gear for burrs and roughness, and consider some fine filing.

Thanks for sharing your experience Ray!

In a lot of starters, the spring is not even there. The inertia of the spinning pinion sends it back out of engagement by means of the spiral grooves in the shaft once the engine is turning faster than the starter.

It is possible that the pinion got a little tight on the shaft and did not return out of engagement.

Some plastic swells with age or heat, or maybe a little residue held it up.

I think if I had an Onan, I would pull the starter and be sure things looked good and give it a good cleaning.

I closely checked the ring gear and it looks new with no burrs or wearing. Based on this, I also presumed the return spring disengrated causing the wear on the gear. Since the starter is easier /cheaper to replace, I am glad it was designed with the plastic gear.
Onan was running ok, timing was good but could not confirm if someone shot her full of starting fluid at some time.
Regardless, for the Onan owners this maybe something to check or carry as a spare.

quote:

Originally posted by bill h:
I don't think so. As long as the engine is turning faster than cranking speed, the spiral grooves on the shaft should force the pinion back out of engagement, regardless of the starter turning or not.

The starters I work on do not have that type of light duty setup.



Here is what a bendix on a big diesel looks like. As you can see on the top side, it's a ratcheting clutch drive.



While I understand the spiral concept, I would figure that the constant thrashing of a bendix not returning to its seated position could have caused this, just like it does on the big starters when they fail. Unless I had one in my hands to look at, I'll defer to you on this one Bill.

quote:

Originally posted by bill h:
It is possible that the pinion got a little tight on the shaft and did not return out of engagement.

Sounds more plausible to me too.

My barstool opinion is that a proper spiral drive pinion does not even need a spring.

They do need to be clean and lightly lubed. Grampaw used kerosene for both. worked fine.

El Segundo Bill's Grampaw went to the same school as my Dad. On the farm, kerosene was the universal lubricant, rust preventive, & rust cleaner-upper. If you couldn't break it loose with kerosene, or penetrating oil that came in a tiny little can, it wasn't worth saving. There was no fancy, effete, stuff like WD-40, PB Blaster, etc.. Even went into Grammaw's spring tonic, though lucky for me, my mother was a little more modern.

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Originally posted by olroy:
El Segundo Bill's Grampaw went to the same school as my Dad. On the farm, kerosene was the universal lubricant, rust preventive, & rust cleaner-upper. If you couldn't break it loose with kerosene, or penetrating oil that came in a tiny little can, it wasn't worth saving. There was no fancy, effete, stuff like WD-40, PB Blaster, etc..

It is interesting to note that the WD40 you mention is essentially kerosene.

Most farms kept kerosene around for all sorts of uses, but the primary function started out as engine fuel and heating. We had several portable heaters that could be used to make a cold shop or garage warm enough to use in winter.

We had a kero immersion heater that would keep the stock tank from freezing solid. Quite like the immersion heaters that later heated the dreaded C rations in the Army.

We had engines and tractors on the farm that started on gasoline, then,when warm, were switched over to kerosene, which was much cheaper.

To add to your uses, kero was mixed with goose grease and rubbed on the chest of a child with a cold. Or a drop soaked into a sugar cube as a cold medicine.

Of course, all that was only if the bag of asifidity didn't work.

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Even went into Grammaw's spring tonic.

Gramma was a WCTU supporter, but she did like her tonic. I suspect it had a little something in it beside kerosene.

But, I do remember a muscatel that tasted of Kerosene.

There are lots better lubricants than WD-40. I remember that this stuff was originally used to coat ejection seats in the F-8 and F-4 to prevent corrosion at sea but it was prohibited after it was found to evaporate the kerosene base leaving behind a sticky residue. It was responsible for several unsuccessful ejections during my early career and after that it was not even allowed aboard carriers. Today they use this: http://www.qclubricants.com/milprf32033.htm
It is available commercially in spray cans.

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Originally posted by Tom K:
There are lots better lubricants than WD-40.

Amen to that.

At work, we always found a superior product for every use.

Well.........we still used it for our potato cannons because it was available.

I put WD-40 in the same category of tools as bailing wire and duct tape. Useful, but not always the final solution to my problem.

Interestingly, the WD in WD-40 stands for 'water dispersing' and the 40 represents that the formula was the 40th attempt to create the water dispersing characteristics the chemists were seeking.

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Originally posted by ForrestKing:
...the WD in WD-40 stands for 'water dispersing'...

I have used this many times to dry out wiring for ECM's on the electronic diesel engines. Salty Water, from winter road spray, and trace electrical currents play havoc with wiring harnesses and ecm readings.

Temp repair to get em off the road. Good for distributor caps too.