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adsm08

School me on Starter/Generator systems

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adsm08

Ok, so I am extremely familiar with regular automotive alternators and starters. I understand that they are basically different sides of the same coin, and all the principals they work on. I am however, somewhat baffled by a charging issue that I may or may not have one anywhere between none and both of my Wheelhorses.

 

So I burnt out the regulator on the 855 (grounded the L terminal with the engine running and burnt up a coil). This was at the end of a weekend full of stop/start work when I had killed, and then charged the battery with a charger. It was hard to start, worse after I got the hydro pump fixed and hooked up, so I checked the battery and it was low. I chalked it up to the frequent stops and starts, and just put it on a charger.

 

This week I replaced the damaged regulator, and replaced the missing generator warning on the 855. My ammeter shows a steady state of zero with the engine running, not charging or discharging, it does dip into discharge if I turn the lights on, so I think it is working. But now after I replaced the warning bulb, it is on all the time. It come on with the key, flickers a bit after start up, and then stays on. I have a static battery voltage of 12.55 key off, and a running state of a fairly steady 12.3, so I am clearly not charging. At the forward post on the S/G, that has the big wire attached, going back to the S-terminal of the key switch, I have zero volts.

 

I have checked all the wiring per this diagram, and it all seems to be correct. Grounding the F terminal does nothing.

 

Now for the confusing part.

 

My 800 Special appears to have a nearly identical S/G system. The regulator is slightly different, having only three posts, instead of 4, and the 800 has no charge indicators of any kind, but otherwise appears the same. I have been attempting to compare the way it works, its voltage readings, etc, against the 855 to try and identify where something is not working. I get pretty much all the same readings, including an engine running voltage of approximately 12.3V at the battery, which is identical to the key off voltage to within a few hundredths of a volt. If I check the voltage between the battery and the forward terminal of the S/G, which is presumably still hooked to the S terminal of the key switch, I get a reading of 28V.

 

Now I am not sure which, if either, set of readings is correct, but it also appears to me that without any power present where the large wire goes into the S/G it can't put any power back into the system, since the F-terminal connection to the regulator is the only other wire going to it, and it is much too small.

 

So does all this mean that the 855's S/G unit is not functioning, and if so, what failure could cause this set of symptoms without disabling it's ability to function as a starter?

 

 

855 wiring.jpg

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Mike'sHorseBarn

I believe the field coils inside the unit are what makes it charge, they could junk. Could be the brushes too. I'm having the same problem with my 855 right now.

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jabelman

what I thought was a s/g is sure on my 854 was a wiring issue.  a full rewire fixed it the issues. alot of the 1964 was heavily oxidized etc even though the casing looked good

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squonk

If there is a auto electric shop near you, take the genny in to get tested. Brushes stick, commutators oxidize, field wires break ect.

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adsm08
12 minutes ago, jabelman said:

what I thought was a s/g is sure on my 854 was a wiring issue.  a full rewire fixed it the issues. alot of the 1964 was heavily oxidized etc even though the casing looked good

 

The tractor is due for re-wire, both of them. My hope is to tackle that between now and the end of the year, once mowing is done, and before snow hits.

 

8 minutes ago, squonk said:

If there is a auto electric shop near you, take the genny in to get tested. Brushes stick, commutators oxidize, field wires break ect.

 

There is a guy just up the street from me who does alternator and starter stuff. I'm not sure what is hours are.

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pfrederi

3 or 4 terminal can be used on an S/G system.  One confusing factoid the wiring diagrams are really based on a 4 terminal Regulator.  The fourth terminal is the Generator terminal on the bottom (Same as the one marked GEN on 3 terminal regulator)  The wire that runs from that to the A terminal on the Genny doesn't show up on the WH wire diagrams as it is a Kohler installed wire.  (Confusing enough????)

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pfrederi

You should have two wires on the A terminal of the generator...One heavy from the starter switch (or solenoid if used) and one lighter wire from the bottom terminal of a 4  terminal or the Gen term of a three terminal.

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adsm08
Just now, pfrederi said:

You should have two wires on the A terminal of the generator...One heavy from the starter switch (or solenoid if used) and one lighter wire from the bottom terminal of a 4  terminal or the Gen term of a three terminal.

 

On the 855 the A terminal does have a wire running to the bottom of the regulator.

 

On the 800 that wire is absent. The "sen" terminal, which I assume is the equivalent terminal there, is hooked to the pull switch for the electric PTO clutch, for some reason.

 

 

Still not quite sure how the 28 volts at the A terminal is turning into 12.3 by the time it gets back to the battery.

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pfrederi

it is the gen Terminal. Take that wire to the A terminal on the generator and see if things work

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adsm08
11 minutes ago, pfrederi said:

it is the gen Terminal. Take that wire to the A terminal on the generator and see if things work

 

Ok, I'll mess with the 800 later. I need some more wire, because the existing one is too short after I take it apart where it is connected to the clutch switch.

 

On the 855 that is already connected and it isn't working.

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pfrederi

If the 855 is wired correctly and you ground the F terminal and voltage doesn't go up then the charge field coil in the Generator is likely culprit

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adsm08
11 minutes ago, pfrederi said:

If the 855 is wired correctly and you ground the F terminal and voltage doesn't go up then the charge field coil in the Generator is likely culprit

 

OK. I plan to go out and tear the generator down after the kids are in bed. Is this something I'm likely to be able to fix myself, or does it require special tools/equipment? Are the coils and windings for these available anywhere or do they have to be custom made or refurbished?

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pfrederi

I always take mine to an S/G guy. 

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pfrederi

he can do more detailed diagnostics, may not be the field coil.  secondly if the filed coil is bad other things may be borderline.  Have you ever undercut a commutator on the armature.  There are You tube videos but I am not trying it.

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adsm08
14 minutes ago, pfrederi said:

he can do more detailed diagnostics, may not be the field coil.  secondly if the filed coil is bad other things may be borderline.  Have you ever undercut a commutator on the armature.  There are You tube videos but I am not trying it.

 

I have not. You don't rebuild automotive alternators in the field anymore.

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953 nut
2 hours ago, pfrederi said:

3 or 4 terminal can be used on an S/G system.  One confusing factoid the wiring diagrams are really based on a 4 terminal Regulator.  The fourth terminal is the Generator terminal on the bottom (Same as the one marked GEN on 3 terminal regulator)  The wire that runs from that to the A terminal on the Genny doesn't show up on the WH wire diagrams as it is a Kohler installed wire.  (Confusing enough????)

image.jpeg

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adsm08

Well I got up early and messed with them. I took the S/G unit off the 855, opened it up, and cleaned it out. I found some mangled bits of copper wire in the case and a busted winding in the armature. It looks like a bit worked its way loose and then got sheared off. I put it all back together not being super hopeful, but fired it up anyway, light went off and the ammeter indicated charging, but the needed was bouncing, for about a minute, then the charging system shut down again. Looks like I will be getting this unit rebuilt.

 

Then I worked on the 800. Connecting the gen terminal to the A terminal has it regulating, but did not increase voltage at the battery, so I need to charge the battery (needs that anyway) and go through my wiring.

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jabelman

s/g's and original carbs if you see them cheap at sales pick them up to keep on hand.  it gives you something to rebuild in the winter months, then you have a few good ones on hand

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kasey54

I think  isavetractors.com sells the windings.

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kasey54

Yes they do I just checked for Delco Remy.

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adsm08
1 hour ago, jabelman said:

s/g's and original carbs if you see them cheap at sales pick them up to keep on hand.  it gives you something to rebuild in the winter months, then you have a few good ones on hand

 

And now that I have some extra money coming in I am planning to do just that.

 

1 hour ago, kasey54 said:

I think  isavetractors.com sells the windings.

 

I was looking at this rebuild kit on eBay. It has pretty much everything.

 

 

https://www.ebay.com/itm/Delco-Starter-Generator-Master-Rebuild-kit-Field-Coils-2-Bearing-Armature-CW/202170989338?hash=item2f12547b1a:g:5HQAAOSwGUBaTA7B:sc:USPSPriorityFlatRateBox!17019!US!-1

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pfrederi

That is about what my S/G guy charges...he does the work and if there is an issue he fixes it free.

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adsm08
14 minutes ago, pfrederi said:

That is about what my S/G guy charges...he does the work and if there is an issue he fixes it free.

 

I am gonna wait until tomorrow and call a few alternator/starter places around me and get some prices. If nobody is close enough I'll order that kit.

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adsm08

So I wasn't able to find anywhere near me that advertises for this kind of work, so I bought the rebuild kit, and it arrived last night.

 

I rebuild the starter over lunch, but it doesn't seem to work right. It does spin clockwise, but slowly and it will start cranking and slow down until it stops. The first time it stopped cranking I couldn't even turn the engine backwards by hand. It also feels notchy when I turn it by hand. 

 

 

I took a picture of all the internal connections and tried to copy it as closely as I could, but is it possible I have one coil wired backwards? Is there any polarizing I have to do?

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Mike'sHorseBarn

There is a shop in mifflinburg called white springs repair that does excellent work on starter generators. I've had 4 done there. I know that's a bit of a trip for you but it might be worth it.

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