Onan 4000 ky no start

[tonym]

Thanks, Hacksaw Ill check it .

[Rich Biebel]

Your problem sounds like one I have seen a couple times.

The timing is off and here is why....

The engines crankshaft is keyed to the generators rotor. The rotor is keyed to the blower wheel and the timing is triggered by that blower wheel.

Either the blower wheel moved or more likely the rotor moved on the crank.

All tapered shaft connections and the crank to rotor has a little pin to locate it. The blower wheel has a key slot and a very small key. Once it's all bolted together the taper holds it. A backfire probably happened and sheared the pin at the rotor to crank connection and it moved.

If you have good spark, fuel and good compression this is likely your problem.......It should at least try to fire with carb cleaner sprayed into carb throat cranking. If it pops back or does nothing and you confirmed the spark is good......the timing is off and one of the above 2 items moved....

Like I said I have seen it at least twice and I fix these machines for years and years.....

If it cranks and has spark, it should at least start and would shut right down if it had no AC output or a bad control board. Bad boards sometimes burn up and won't even crank.....

[tonym]

Many thanks,Rich I think you are correct. It sounds like it is trying to fire on exhaust stroke.


Can you guide me to how to approach the repair? How much disassembling is required to inspect the components etc and what do I look for?


Do you still run at Island? Think I remember you when me and my son raced there.! I live over in Brodheadsville near Stroudsburg.


Thanks Again.

[Rich Biebel]

It's pretty difficult to describe and is a lot to disassemble. The entire generator end has to come apart. A service manual might help but you'd be better off taking it to a professional, like me that is familiar with them. It's not a simple deal to take it all apart and know what you are looking for. I work for a generator service company in Dover, NJ. I do all the RV work so I know those machines very well. I don't race at Island and have not for years. What racing I do is usually in S/C at various races and tracks. Maybe there is an Onan repair place somewhere in your area. You could buy a service manual online but it's not real helpful for a repair like this. There really is no other way to check this other than disassembling it to verify the timing indexing is either good or bad. A new rotor may be needed if the pin broke as it is not repairable. Parts availability is a possible issue but should be available.

[tonym]

Thanks again, Rich
The unit is out of trailer and in my pickup. If you do any work on the side I can drive it to your place and leave it. I suspect I am only an hour or so away.
Assuming that's the problem can you give me a rough estimate to fix it . I don't want to put a lot of money in it if its not worth it.
Thanks so much


Tony

[Rich Biebel]

Tony.....The rotor is shown as not available on Cummins website.....and sells for over $500....

If the machine was in good condition and not a mess like some I see the cost to replace that rotor and probably a few other items would push the repair cost to at least $750. Assuming it is the rotor and replace the brushes at the same time.....and make sure it is running right and adjusted as well as possible....

At work I use a load bank tester to adjust a machine for best operation.

Those machines have a service life and since they run at 3600 rpm the engine gets worn over time. I shy away from doing any major repairs on one if it looks to be in rough shape....Not worth it.....

I really don't do side work anymore......

[Hacksaw]

Originally Posted by tonym

Thanks again, Rich
The unit is out of trailer and in my pickup. If you do any work on the side I can drive it to your place and leave it. I suspect I am only an hour or so away.
Assuming that's the problem can you give me a rough estimate to fix it . I don't want to put a lot of money in it if its not worth it.
Thanks so much


Tony

Hey, that's not cool to put Rich in a pickle like that. The man makes his living working on gen sets and freely offers helpfull advice on a regular basis. Don't ask him to sidestep his employer, even if he owns the company.

[Jim Wahl]

Had a Onan Quiet 4000 in my Class C RV and had nothing but problems. Not starting and shutting off whenever it felt like it. Had it in to the Onan repair dealer 6 times in 3 years. Lucky to have a good shop here in Orlando. Many racers I have spoken to have had the ame problems with those models. The last (and final) time it broke a rod! That was it for me. Traded it in for a class A with a 6500 Onan and never looked back! Jim


.