Community Forums

powderman · 06-25-2017, 09:54 AM

[QUOTE=Kahoona;I hate mieces to pieces!!![/QUOTE]

Thuffering thucatass.

I am following and hope you find an easy fix.

Kahoona · 06-25-2017, 04:41 PM

Quote:

Originally Posted by powderman

Thuffering thucatass.

I am following and hope you find an easy fix.

I love the Loony Tunes quotes. To this day my wife and I cannot pass through Albuquerque without using a Sylvester accent!

OK current results. I have the generator and motor freed from all of it's outer junk. I have pulled the fan/flyweel which includer tapping the three holes to fit three- 2" 5/16 18YPI bolts for pulling. Don't even try to remove the key from the shaft with a magnet. Won't work. Don't be alarmed when the fan/flywheel comes off with a loud ringing bang. You will never find the key.
The manual has been a tremendous help and is pretty detailed.

The resistance between the 2 rings is 22m +/- 1m Hard to get an accurate reading but that is close enough to the required 21.6m in the manual.

The resistance between the rings and the shaft is 38m. The manual says "A reading od infinity should be measured. A reading of less than one megohm indicates the rotor ic grounded . Replace" 38m is much higher than 1m so although not infinity I hope this is close enough. I am thinking about pulling the rotor to see if dust, dirt and possibly a ground up rodent (pun intended) might be causing a partial ground. I do not see any mouse damage from the outside and the rings look clean though slightly scratched.

I have sent these results to the tech at the Partsfortechs.com store. He said he would be able to tell me if I needed a new brain given this info.
I would like to hear anything other people have found since I am inexperienced with generator repairs. Tomorrow I will check continuity on every wire I can trace and clean things up a lot. I am also waiting for parts for it's AC. I will let you know if I get a reply and will check here regularly. Thanks all.

okcnewbie · 06-26-2017, 05:52 AM

Quote:

Originally Posted by powderman

Thuffering thucatass.

I am following and hope you find an easy fix.

It's way past that. Once you pull the genset than pull the flywheel it's not easy. It may end up being cheap, but it ain't easy.....lol

okcnewbie · 06-26-2017, 06:05 AM

Quote:

Originally Posted by Kahoona

The resistance between the 2 rings is 22m +/- 1m Hard to get an accurate reading but that is close enough to the required 21.6m in the manual. ......

I'm pretty sure you mean 22 ohms not megohms. That sounds right. With out a megohm meter different meters will likely read a little different as you approach infinity. It sounds like the rotor is probably ok.

Quote:

Originally Posted by Kahoona

I would like to hear anything other people have found since I am inexperienced with generator repairs. Tomorrow I will check continuity on every wire I can trace and clean things up a lot. I am also waiting for parts for it's AC. I will let you know if I get a reply and will check here regularly. Thanks all.

My rotor was open (slip ring to slip ring). I attempted a repair but the laminate stuff was coming apart and it caused the rotor to stick out too far.
My second onan stopped (even with running it every month) and while inspecting I noticed pieces of the rotor in the bottom of the genset tray. Other parts; Voltage reg. Unit ran but couldn't adjust to load (if I remember right)

okcnewbie · 06-26-2017, 06:12 AM

Quote:

Originally Posted by Kahoona

. I am thinking about pulling the rotor to see if dust, dirt and possibly a ground up rodent (pun intended) might be causing a partial ground......

Whatever you do..... don't use various drill bits to help get the rotor off. I know a guy (name to remain anonymous) that did this and then the drill bits exploded in the shaft. He then (pretty sure it was a he about 6'2") had to drill through a bolt that threaded onto the shaft. Then attach a grease fitting to the bolt. Finally used a grease gun to get the rotor off. In the end it was pretty cool. I guess guys having been using grease guns to get motorcycle calipers off for years. Go figure.

Kahoona · 06-26-2017, 08:39 AM

Quote:

Originally Posted by okcnewbie

I'm pretty sure you mean 22 ohms not megohms. That sounds right. With out a megohm meter different meters will likely read a little different as you approach infinity. It sounds like the rotor is probably ok.

Glad you figured that out. Sorry for the lapse. Yes the rotor measurement was ohms.

PS your rotor is a mess! Serious damage there.

The grounding measurement was Mega Ohms

Could the lack of an infinity reading be due to all of the desert dust and road crud packed into the winding? Should I try to remove some of it? Compressed air or water?

Sounds like I am going to need a board.

Kahoona · 06-26-2017, 12:22 PM

Ran into a problem trying to test the Stator. I simply cannot get the plugs our of the tops of the Stator sockets. I know that somewhere there is a catch in there but I cannot find it. This is too serious to just force them. Has anyone here done it?

okcnewbie · 06-26-2017, 03:20 PM

I wouldn't be afraid to try compressed air on anything.

What is the top pic of? It's reading 235 ohms.

After you clean the slip rings and don't find anything wrong I suspect you'll give it another go?

If the stator looks good I wouldn't suspect it and would try it.

Kahoona · 06-26-2017, 04:20 PM

Quote:

Originally Posted by okcnewbie

I wouldn't be afraid to try compressed air on anything.

What is the top pic of? It's reading 235 ohms.

After you clean the slip rings and don't find anything wrong I suspect you'll give it another go?

If the stator looks good I wouldn't suspect it and would try it.

Top pic was to be of ring to ring which hadn't settled down when I took the pis. It normally reads around 22 ohms.

I found that the stator connector contacts are different than the diagram but close enough to figure out. They are not grounded and the resistances are close.

I need to trace and test the wiring still but I am glad it is OK so far. It will have been worth the trouble of taking it because I can now replace the rubber feet and add some sound deadening material on the RV compartment itself. It has gotten louder over the years.

Kahoona · 06-30-2017, 08:14 AM

In for a penny......
Status report. John at partsfortechs.com has given me some tests to do. Same as the ones in the J spec manual. Rings are black indicating arcing. Resistance is OK on rotor. Grounding is within specs but not so good. He would like to see a new rotor in there as well as a new board. Theory is that the brushes may have been making poor contact and arced a lot frying the board. The brush holder was screwed in too tight when the generator was made and it cracked under the screw. My next job is to get the endbell off and the rotor out and inspect it. I can clean the rings and clean out some of the dirt and dust to see if the ground improves.
I found a new old stock wiring harness on the bay so I will replace it to eliminate chance of cracked wires. Easier than cleaning them up and testing all. Right now I am stuck at removing the endbell. The bearing for the rotor is stuck in it. I can get it out eventually though. I'll let you know when the rotor is out. Pics to follow. If that rotor is bad that's some money!
Getting new board. Isolater feet, brush holder, springs and brushes are on order. All suggestions are welcome!

okcnewbie · 06-30-2017, 12:05 PM

I think you need a new rotor as well.

Do you even have an estimate of what everything would cost with the rotor? It's awesome having a working Onan but they can be money pits. A few people have been able to install starting kits in their 13.5k AC units and run off or one 2K unit. (pretty sure) That would mean the predator on sale at HF for 429 might do the trick. Even if you need two and the parallel kit. Less than 1k. All that is keeping me from dumping more money into my onan. Of course, if you're sending me a rotor........

p.s. Can I have the old rotor?

Kahoona · 07-01-2017, 10:38 AM

Quote:

Originally Posted by okcnewbie

I think you need a new rotor as well.

Do you even have an estimate of what everything would cost with the rotor? It's awesome having a working Onan but they can be money pits. A few people have been able to install starting kits in their 13.5k AC units and run off or one 2K unit. (pretty sure) That would mean the predator on sale at HF for 429 might do the trick. Even if you need two and the parallel kit. Less than 1k. All that is keeping me from dumping more money into my onan. Of course, if you're sending me a rotor........

p.s. Can I have the old rotor?

Might get to $800 if I need a rotor. Then lets not forget the Stator too. Never know. I am retired and was not prepared for this but hey...I'm boint go hit the road again in a month or so so... My reasoning is-

I need a 4 k generator. In hot places I don't want to turn off the AC to run the Microwave/ coffee maker, fans or charge the batteries.

I need one that fits in the RV space provided.

A replacement Onan would be about $3200 plus shipping new.I hate to even think what a better one would cost if one would fit.

I haven't seen any barely used Onans that wouldn't be old enough to break all of the time.

For these reasons I thought that anything up to around a thou would be reasonable for a unit that I know works well. If there is a cheap, nice low hours used one perhaps that is better. I figure to clean this rotor up and check it again and perhaps even check and clean the stator before we decide. Has to come out either way. Then I can look at the possibilities.

Kahoona · 07-01-2017, 05:16 PM

I would be happy to give the old rotor but this one is going back in!

When I was pressure washing all of the old case parts I noticed this and had to take a pic. You can clearly see how the water from the wet road and front tires went right into the intake and made a swirl pattern on the back of the cover! It would only have taken a little trouble to baffle that flow. I am glad I installed a side intake. Might even add a baffle.

The rotor removal is straightforward but you have to do exactly as the manual says or you could wind up destroying the threads on the crank end.

I am still working on the rings. They have a remarkably tough black coating but it is coming off. I do think that the brushes were not centered on the rings because of the badly installed holder. The rotor was only slightly dirty but after blowing it out carefully it passes the ground test with a reading of OL. Perfect. No signs of burning or hot spots.

I blew out the stator also. It was dirtier and took quite a while to get it cleanish. I didn't see any hot spots and everything looked intact. No ground mieces inside.

. It also reads OL between case and all pins. No grounds. Whew!. These were what had me worried because they get all of the junk thrown at them from the rotor. I was prepared to clean them with non chlorinated brake cleaner if necessary but it was not.
I have acquired a tame small/large engine and generator mechanic who is helping me out with advice.

That is it for now. I am cleaning case parts while waiting for new parts to come in. I sure hope it runs right away!

New trick (for me). I was trying to get the rotor out and turning on that bolt with a breaker bar but the motor would turn. I was talking to my neighbor about adding oil to the cylinder to lock it and he told me to just pull the plug and stuff the head full of rope! It does a great job of locking it without the mess.

cimplexsound · 07-04-2017, 01:34 PM

If the genset runs then there is no need to replace the rotor. You should check the transfer switch. (The transfer switch is installed on the genset just behind the start/stop button) When you release the start button the transfer switch on the genset is suppose to stay on unless you hit the stop button or plug your RV into shore power. In this case the transfer switch would automatically shut the genset down. So this an electrical issue and the transfer switch is the first place I would check for shorts or loose connections. These gensets usually weigh in ay a whopping 300 pounds so if you don't have to mess with the motor, don't. Cummins builds an awesome genset, I've seen these things sit around for year with no use and they start up on the first turn. Also you can clean it with compressed air without taking it apart or taking it out of the RV. Just remove the motor cover, and air filter and give it a good blow. The dirt will be expelled from the shaft when you fire up the genset.