1989 520H Electrical Help

[Actonhorse 26]

I recently picked up a 520H.  The PO told me that it is not charging and the tach and hour meter are not working.  I started digging into it today.  The first thing I did was put a new battery on it. 

It runs great with the new battery but in testing it doesn't appear to be charging as he told me.  The tach goes to 0 and stays there.  The hour meter doesn't work.  I cleaned up all of the relevant connections including the battery connection and I checked continuity from the terminal on the rectifier/regulator to the tach and I have continuity.  I checked the stator leads with the engine running and there are only 4 volts showing.  Also, while checking I noticed that with the tractor not running and the key switch in the off position I have 12 volts on all three terminals on the regulator.  I am thinking either the regulator or the stator is shot but the voltage on all three terminals has me wondering about the key switch. 

Can anyone tell me if I am on the right track with the stator or if I should be looking at the key switch? 

Does the tach and the hour meter have anything with it not charging? 

I haven't dug into too much of the other wiring yet. I can only find 2 fuses.  I don't seem to have a fuse block like I have seen in pictures...  Could that make a difference? 

 

Any help is appreciated. 

 

[Ed Kennell 35,615]

Check the AC voltage across the two wires from the stator with them disconnected from the RR and the 520 running.  You should have 25-35 volts AC at wide open throttle.

I repeat AC not DC.

Edited January 3, 2017 by Ed Kennell

[Actonhorse 26]

Yeah, that's what I'm saying Ed.  I got 4 volts AC when checking across the two wires disconnected from the RR.  Does that mean the stator is most likely bad?  I checked for a ground short as well and there isn't one. 

[Ed Kennell 35,615]

Yep,  you got a problem under the flywheel.  Sorry.

[Actonhorse 26]

Ah, don't be sorry!  I was hoping someone could confirm that for me before I dug into it!  thanks for the help. 

[Ed Kennell 35,615]

I guess the only hope would be if there is a break in one of the AC wires.    You could check continuity with a needle close to the flywheel.

I assume you know how to " search" for the manuals for the Onan.   @boomers_influence  is our local guru on ONAN engines.

 

BTW, the tach is triggered by the second wire on the rear AC tab on the RR. So w/o AC, it will not work.

Edited January 3, 2017 by Ed Kennell

[Actonhorse 26]

Yes, I have the manuals.  Good idea on the continuity, I'll check that before buying a new one.  That makes sense why the tach isn't working - the PO mentioned that it stopped working around the same time it stopped charging.......

[Ed Kennell 35,615]

Please keep us updated with your repair...and    

[WVHillbilly520H 10,369]

Last one that the hour meter and tach didn't work on, I changed out the R&R first and all started working, easy to get to and a cheap start with diagnosis, just my experiences,Jeff.

[squonk 38,845]

Another thing those hour meters are junk. An easy test for it is one terminal has power and the other terminal grounds thru a separate contact with the engine running. Take a voltmeter and check continuity to ground on the 2nd terminal after you get the charging problem fixed. If you have 12V and ground the meter is bad.

[cleat 4,936]

I have never got a 520 with a working hour meter yet.

I install digital ones.

However, the hour meter works on my little 111-6.

 

 

[Actonhorse 26]

So. Stator it is  First a pic of the tractor    

 

Then some pictures of the bad stator. The copper is supposed to be a continuous winding and this one has several breaks due to corrosion. I'm not sure how that happened but im thinking it is just time. 

 

And one of the backside. There are more bad spots but this definately explains the charging problem. Now to fina a new one and a Regulator. 

 

So. Stator it is  First a pic of the tractor    

 

Then some pictures of the bad stator. The copper is supposed to be a continuous winding and this one has several breaks due to corrosion. I'm not sure how that happened but im thinking it is just time. 

 

And one of the backside. There are more bad spots but this definately explains the charging problem. Now to fina a new one and a Regulator. 

 

[Sarge 3,462]

I'd spend some serious quality time cleaning that engine - that amount of debris is a recipe for overheating and failure ...used parts show up here and on SleazeBay often...

Sarge

[Actonhorse 26]

Yup, that's the plan.  Take the rest of the tins off and give it a good cleaning.  I've seen worse but I have read about these onan's getting hot and I'm going to do it right. 

 

 

[cleat 4,936]

That is quite an unusual decal set on that tractor.

Are those small lights near the bottom of the hood ?

 

Good looking 520

 

Cleat

[GlenPettit 1,714]

ActionHorse:

Could you also post photos of the sides and rear of your 520, I would also like to see those side-lights and decals.

Very nice looking tractor modifications, and your closeup photos and descriptions  (thread subject) is very helpful & timely.

Glen

 

[Ed Kennell 35,615]

A lot of posts available on keeping the rear cylinder cool.   Oil filter base gasket leaks, oil filter to tin seal, belt guard vents etc.

[Actonhorse 26]

I'm always amazed at the detail you guys notice on these tractors!  The PO is a body and paint man at a shop I have used over the years.  He called me just before Christmas to see if I would be interested in this tractor and of course I said yes!  He had given the body a paint job about 10 years ago - not a full off restoration just a refresh and had their shop decal person make him a set of decals that he thought worked.  He also installed the tear drop lights along the bottom of each side of the hood.  They look very cool at night!  If you look close at the side of the hood he also did some custom pin striping. 

And yes, he did tell me it wasn't keeping the battery charged but didn't know what was wrong - I knew what I was getting into! 

 

Glen:  I'll post some more pictures of it tonight. 

[Actonhorse 26]

So, it was a good day.  I have the 520 back together and charging. I haven't been able to get a replacement stator so I spent the day degreasing and cleaning the motor. Changed the oil, new plugs etc.  I got to the point that I needed the stator so I started looking around my parts pile. I found a stator off of a Koehler single cylinder that came on an engine that had a broken rod and the block is cracked. After examining it it is almost exactly the same as the Oman.  18 poles, same bolt pattern. Just a slightly different winding-probably 15 amp.  The leads come off it in a slightly different spot as well but with a slight modification it fit.  I got it all together and checked the output and I have about 45 volts ac across the leads!  Once I had the rectifier regulator hooked up I am getting 14.7 at the Center terminal!  It might not be the correct stator but it looks like it is working. You guys can tell me if I'm doing something that will hurt the tractor.  

Oh and a bonus is the tach and voltmeter are both working again.  Still no hour meter but tomorrow is another day. 

 

Here is is a picture of the tear drop lights on the front of the hood. 

 

[cleat 4,936]

Can't see you hurting anything.

 

Lights look good.

 

Make me think of European cars with the lights on the fenders.

 

Cleat

[SylvanLakeWH 24,093]

Very cool! And good fix out of the parts pile!