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Peter27C · 08-08-2016, 10:37 PM

Was at an Onan Dealer yesterday and am being told that my 18 month old P series Onan 4000 Microlight is only good for about 450 to 650 hours before needing to be removed from the coach, stripped down and the generator brushes needing to be replaced. My last coach did around 1100 hours on the generator over 11 years and then needed removal for a starter motor. No problems with brushes in that time.

My questions are:

1/. Is 450 to 650 hours for brushes "normal"?

2/. If you have a microlight 4000 with more than 650 hours on it, what repairs have been necessary to the generator?

3/. How many hours per year do you put on your generator?

A quick replay would be helpful as I am due back at the Onan dealer this afternoon!

Thanks,

Pete

Dtwallace · 08-08-2016, 10:51 PM

Is that not a brushless generator??????

I don't have the exact numbers, but what you were told makes no sinse at all.

I have one of those generators used to put in my trailer and it has over 2000 hrs on it, and still runs like new...

The person I brought it from did do some refurbishing.

DTW

Peter27C · 08-09-2016, 12:05 AM

It definitely has brushes.

Pete

Petersr58 · 08-09-2016, 06:24 AM

I just was at a seminar put on by Onan. If properly maintained your generator should last many thousands of hours. The key is proper maint. and run it a minimum of 2 hrs per month. It likes to run not sit. You got bad info from that shop. Your Onan dealer should be better informed.

John Hilley · 08-09-2016, 09:21 AM

Check the manual for maintenance interval.

okcnewbie · 08-09-2016, 09:37 AM

You can measure the resistance through the brushes and slip rings without even pulling the generator.
The more you use the generator the better.

Virago-Rider · 08-09-2016, 07:20 PM

How to measure the resistance of brushes and slip rings?

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Peter27C · 08-13-2016, 05:55 PM

Well it turned out that it's not necessarily true that the more you use the generator the better! The brushes had worn out until the wires held them off the slip rings causing a bit of arcing damage. This cleaned up fine. Unfortunately the 4000 needed to be dropped out of the coach and flywheel pulled to access the brushes. New brushes, cleaned slip rings and the gene is running fine again.
Spartan RV near Atlanta did the job and were fantastic. No waiting, immediate start and job done with great efficiency .

What have I learnt? Well the tech said that in his experiance 450 to 600 hours is typically what you get out of a 4000. Atlanta power claimed 1000 to 1500 hours typically. So my suggestion is that if your generator gets hard to start and you have made sure you have fuel and a clean plug it may well be time to check your brushes if you are getting a few hours up.

Pete

okcnewbie · 08-15-2016, 06:26 AM

[QUOTE=Virago-Rider;3201530]How to measure the resistance of brushes and slip rings?

It appears that I was mistaken. I thought I read the resistance from pin 9 through the brushes and back to pin 10 of P4 when troubleshooting several years ago. I suppose a visual inspection is the best for those.

Peter, How much did this cost if you don't mind?

p.s. I still say not using a genset has killed more of them then using them.