Needs a jump

[dwcphoto 7]

Hi Guys,

I'm back with another Onan question. I have a WH 518 and it's been running quite well. I put a voltage regulator in the past summer, but the volt meter on the tractor has not changed much. It does keep running, though, as before it would drain the battery and quit.

I recently took the battery off and charged it as it was weak from sitting in the cold. I finally put the snowblower on last week. Here's the thing now. The battery will turn the engine over well enough several times, but doesn't want to fire cold. I put the jump battery on to assist so I don't run down the tractor battery and bang, it fires right up. Once it runs a bit, it starts off the tractor battery. Any ideas?

Thanks very much. Happy New Year. dwc

[Save Old Iron 1,571]

Check 3 different DC voltage measurements

Running - battery voltage should be 13.5 to 14.5 - too low or high is a rectifier regulator issue.

Cranking - battery voltage should hold above 10 volts until the engine fires - if too low or voltage drops quickly, question the battery capacity.

Storage - battery should be 12.5 to 12.6 volts prior to cranking - if any lower than 12.5 after a full charge - question the battery health.

A marginal battery that starts the tractor fine in 60 - 80 degree temps will not support extended cranking at current winter temperatures. Lead acid batteries are a chemical reaction - chemical reactions slow down at lower temperatures.

[dwcphoto 7]

Thank you. I'll check these things out. Much appreciated, dwc

[dwcphoto 7]

Hi Guys,

  Obviously, it takes me quite a while to get around to the tractor aspects of life! I have a new battery, installed this spring. I checked the voltage on the battery cold and it's 12.7 which should be fine. I only get 12.3 when the tractor is running. I checked the white wires on the regulator and they only indicate 9.3 +- each and the output is the same. I did clean up the wires last year and they don't look bad now. I think the next thing is to tear things down to look at the stator. Would that be correct?  If so, how do I go about finding this stator?  I looked over the exploded views but they are segregated and I don't see a photo of the whole picture.  My inclination is to follow the wires.  Thanks for helping out a non-mechanic.

 
In the meantime, while it's fairly cool, I'll go mow for a bit. Thanks for your help. best, david

[dennist 139]

David, check behind the flywheel and you will find the stator. Good luck.

[dwcphoto 7]

Thanks. I'm sure you'll hear more. best, dwc

[ericj 1,579]

you can do a test to check the stater before tear down. pull the stater wires off the voltage regulator and set your multi-meter to a/c voltage and start up the tractor you should get something like 25 to 35 a/c voltage but i don't remember the exact number of a/c voltage. the onan manual tells you how to do this or somebody that remembers will chime in

 

eric j  

[dwcphoto 7]

Thanks.  Anyone have those numbers?  Much appreciated. dwc

[ericj 1,579]

i checked the onan manual it depends on witch stater you have but between 21 vac @ 1800 rpm's and 47 vac @ 3600 rpm

 

 

eric j

Edited July 6, 2013 by ericj

[dwcphoto 7]

Okay, so now I'm really confused. I check the vac and got between 32 and 43 + depending on how high I revved it.  That would indicate it's working, but I'm only getting 9.3 volts input with direct current and the regulator is only putting out 9.3, of course.  Where do I look next? thank you, d

[ericj 1,579]

i just brought a 518 back from the dead last week lucky for me the wiring was in good shape. on the 518 there is a wire with a fuse in it, 30 amp, it goes from the + terminal on the starter to the center terminal on the voltage regulator if this is the wire you are only reading 9.3 volts on check it carefully and look for corrosion on the terminals at starter fuse holder and voltage regulator. and it never hurts to check the other fuse holders and the 9 pin connector. i blow them out with compressed air and maybe a little wd40 and then blow the excess off with air again, or you could just sell it to me lol

 

eric j   

[dwcphoto 7]

I bought this beast in 96 with a torn seat and rusted hood, but only about 300+ hours on it and a deck for $900.  It's been good to me and still runs, even if it has an issue here and there.  I can't afford to sell it, even if I wanted to.  Replacing this beast would cost thousands.  When I checked the white wires, coming from the stator, I checked them individually. Positive on the wire, negative on the neg batt terminal. I got 9.3 on each and then 9.3 on the other wire on the regulator.  I'll check for rust, especially on the fuse wire.  Appreciate the help. d

[ericj 1,579]

i was joking about selling it , was the 9.3 volts with the tractor running or off i will check mine in the morn but it should be 12+ volts. if save old iron picks up on this he might be able to help out better. i am better at doing hands on then trying to explain it. you could go back and check voltage at the fuse then the outlet of the fuse and keep going till you see were you are loosing voltage.and do you get 12 volts or more at the battery ?

 

 

eric j 

[gwest_ca-(File Mod) 11,392]

Here is one test they do not explain in the manuals.

 

With the engine NOT running check the DC voltage across the battery posts .... red to (+) and black to (-) and record it.

Now move the red lead to the DC+ terminal on the regulator. You should have the same recorded voltage. If not work you way back from the regulator until you find the point of voltage loss.

What this checks is the path the charge current takes to get from the DC(+) regulator terminal to the battery (+) when it is running.

 

Most 520's and perhaps all have this circuit going to the hot side of the starter solenoid where it is on the same post as the battery (+) cable so the ignition switch is not involved.

Some tractor models have this circuit switched so the ignition key must be in the RUN position but the engine still NOT running to do this test.

 

Garry

[dwcphoto 7]

Thanks, Garry. I'll try to run this down. Point of clarification, this is a 518-H (with a 520 rear swapped).   Eric, no problem, you never know whose addicted to old rusty stuff!  The 9.3 was running.  I had more voltage on the battery not running than running, 12.7 vs 12.3.  So I'll start looking at wires, but we can rule out the stator for now, right? thanks, d

[gwest_ca-(File Mod) 11,392]

518-H and 520-H use the same diagrams

 

Garry

[Save Old Iron 1,571]

you guys have this one nailed down 

 

a bad wiring connection between the regulator output and the battery

[Save Old Iron 1,571]

The connection from the B+ terminal of the regulator to the battery goes thru the 30 amp fuse holder - often a culprit in any electrical issue with any 500 series.

 

Edited July 7, 2013 by Save Old Iron

[Save Old Iron 1,571]

The issue with low stator output was due to you measuring the voltage of each leg of the stator using battery ground as your reference. When measuring stator output, use your AC volts function of the meter and place the leads directly across the stator leads - or directly across the AC terminals of the regulator assy.

 

[Save Old Iron 1,571]

I had more voltage on the battery not running than running, 12.7 vs 12.3.

 

This is expected. When the engine is running. voltage on the battery will drop as the battery is no longer receiving a charge. Under proper charge conditions, the voltage should be near 14.5 volts DC measured from battery ground.

[dwcphoto 7]

Thanks!  I know how I'm spending most of my Sunday morning... david

[Save Old Iron 1,571]

If you do end up needing to splice in a new 30 amp fuse holder, be sure to purchase a 30 amp version in the auto parts store. They do have heavier duty contacts than the 20 amp versions.

[Save Old Iron 1,571]

an example of a poor connection on a regulator assy - the green corrosion creates a poor electrical connection

 

[dwcphoto 7]

Thanks. There was some fine corrosion on the fuse plug, which brushed off easily. Should I replace the fuse holder since it's hard to get inside of it? thanks, d

[ericj 1,579]

i wouldn't just replace the fuse holder with out checking further, like i said before check your voltage on both sides of the fuse and then try to spray wd40 in and blow out excess and recheck. if you just replace fuse holder it is a site for possible future problems. that may not be a real issue or a fixable issue anyways.

 

 

eric j