Starter/Generator Rebuild

[rmaynard 15,519]

The Delco-Remy starter generator on my 856 does a fine job of starting, but it does not charge the battery.

It's a model #1101973 6C.8

Here are my symptoms:

With the engine running at moderate speed, the voltage at either the "A" or "F" terminal is only 1.9 to 2.5 volts. This is with the regulator removed.

With the S/G belt removed, if I run the motor, and ground the "F" terminal, the motor doesn't bog down, it just stops like I disconnected the power.

The resistance reading between the "A" and "F" terminals is 10.5 ohms.

So I am thinking that I have some bad stuff going on inside.

Questions:

Do we have a tutorial or a thread on RS for a rebuild of a starter/generator?

If not, and if mine is rebuildable, I will document the process and post it here.

[MikesRJ 552]

I have a tutorial. Wanna see it?

[rmaynard 15,519]

I have a tutorial. Wanna see it?

Sure...

Thanks for the manual Mikey :woohoo:

[MikesRJ 552]

http://www.mywheelhorse.com/graphics/file/...1_1972-SM-2.pdf

Great little "tutorial" on just what you need, starting on PDF page 25 (manual section 7.1).

[Martin 2,132]

http://www.mywheelhorse.com/graphics/file/...1_1972-SM-2.pdf

Great little "tutorial" on just what you need, starting on PDF page 25 (manual section 7.1).

mike,

thanks for the link.

just started doing some reading in the section you mentioned as i too, am interested in rebuilding a starter gen. lots of very good info here. im sure the rest of the manual has good detail too.

and thank you bob for starting this thread.

[stevasaurus 22,767]

I too am interested...got one on my 702 that I am just dying to tear apart..it is a starter generator on my 7hp Kohler. I think they are all pretty much the same. This could be a great thread...I was going to wait until fall though...after the shows in August. Want to see what you come up with Bob. :D

[Martin 2,132]

the info on regulator adjustment is just what ive been after. the 875 reg has been screwy ever since i got it. was going to just buy another one, but armed with this info im prepared to mess with it and try and get it working properly.

thanks, guys.

[rmaynard 15,519]

The project begins. I have removed the S/G from the tractor. Here is a picture before I open it up.

I ordered a couple of kits from an eBay vendor. I am getting a new stud kit since I know that one of the stud insulators is broken (I repaired it earlier), and a brush & bearing kit.

As soon as I open up the S/G, I will post more pictures.

to be continued...

[HorseFixer 2,012]

:woohoo: got a couple to do myself.

Cheers ~Duke

:D

[smokin joe 31]

I'm looking forward to this too :woohoo:

[MikesRJ 552]

Hey Bob!

Is that a real live Wheel Horse part, that you own, from a machine you own, with pictures you took yourself, in the privacy of your own home?

Get-er-done! :D

[stevasaurus 22,767]

Mike...if I did not know any better...I"d think you were getting squirrelly. The Horse Doctor recommends some nuts in your diet. and maybe an apple. :D

[buckrancher 2,679]

more than likely your voltage regulator is bad. Normaly if the starter generator

turns the motor over to start it's alright and if you are not charging the regulator is at fault

but with that said a good clean out inside and new bearings and brushes never

hurt anything besure to clean the commutater with some fine sandpaper

or scotch-brite

good luck

Brian

:woohoo:

[rmaynard 15,519]

Thanks Brian. That's what I originally thought too, but as I was telling Mike, with the regulator completely disconnected, I am only getting about 2.5 volts out of the generator.

[MikesRJ 552]

One point to make here concerning the starter generator function.

The first image below depicts the internals of the starter generator, which shows two distinctly different windings.

The first winding is that of the armature, and is harder to identify in the image as it is the wire wound around the rotating part of the S/G. The second pair (not shown in the image as a pair but more times than not a S/G will have two field windings) of windings are the field coils mounted to the inside periphery of the S/G case, between which spins the armature.

The case of the Starter-Generator is electrically grounded (because it is physically bolted to the engine) and the S/G has two posts coming out of the the side of the case. The posts are labeled (or at least represent) "A" and "F" respectively. "A" standing for "Armature" and "F" standing for "Field". One end of each of these windings is connected to the S/G case ground, the other end of the windings are connected to their respective terminal post.

When voltage is applied to the S/G (for engine starting duty) the battery negative is connected to the engine (and therefore to the case of the Starter-Generator), and the positive voltage is sent to the "A" (Armature) terminal to make the motor turn the engines flywheel. Power going to the "G" (generator) terminal on the regulator passes battery power to the ignition system (through the regulator) while the engine is cranking, and is removed once the engine is running and the voltage regulator is supplying power to the "L" terminal.

Once the engine is running and the starter key (or button) is released, power is removed from the "A" terminal. The"F" terminal is then emitting voltage based on the Field Coils design to "pick-up" (a phenomenon called electromagnetic induction) electrical current from the rotating armature. This field voltage is sent to the voltage regulator so it can produce charging current for the battery, as well as supply electrical power for the engines ignition system and the tractors accessories.

All that gibberish said, it is possible (however unlikely it may be) that a S/G could have a good armature coil and a faulty field coil. So, just because the motor turns does not necessarily mean the field windings or "F" terminal post are in good shape.

The second image shows the S/G in two of its typical applications, with and without a starter solenoid. You will notice that the regulator is marked "F" (Field), "BATT" (Battery), "L" (for Load), and "G" (for Generator).

The "F" terminal is the input voltage from the S/G field coil(s), the "BATT" terminal connection is the battery charging current output (and therefore goes through the ammeter so you can "see" charging occur), the "L" terminal is the output of the regulator (connected to the electrical "load") which powers the ignition system and the tractors accessories, and the "G" terminal on the right of the regulator passes battery voltage to the ignition system, but only when cranking the engine. The "L" terminal supplies voltage to the ignition system once the engine is running, the S/G "F" terminal is outputting power, the regulator is producing "load" voltage, and the key or starter switch is released.

This may also come in handy:

http://www.mywheelhorse.com/graphics/file/Engines/1R-115.pdf

[Coadster32 793]

Great read and information Mike. Can you possible re-post up the pics? I understand the text, and would like to capture the visual to go with it.

[buckrancher 2,679]

Mike do you have a Ohm check for the field coils?

I know they sell them on e-bay

Bob check for a grounding to case problem with the two field coils

brian

[MikesRJ 552]

... Mike do you have a Ohm check for the field coils? ...

No resistance numbers that I can locate, only the voltage checks.

[MikesRJ 552]

Bob, where do you stand with this? :woohoo:

[rmaynard 15,519]

Bob, where do you stand with this?

Mike,

I have the S/G apart, cleaned, new bearings in, commutator cleaned and burnished, and I need to buy a new tip for my soldering gun so that I can unsolder the leads to the posts.

Bob check for a grounding to case problem with the two field coils

brian

Brian,

I found that one strand of the multi-stranded wire to the "A" post was loose and touching the the mounting bracket for the brush.

I've have been documenting with pictures and will post as soon as I get a chance.

[Coadster32 793]

Can you possible re-post up the pics

:woohoo:

[rmaynard 15,519]

Update:

With the starter/generator opened, we see what's inside.

First thing we see is the bearing and the hardened grease.

The next picture shows the bearing, the commutator, the brushes and the "A" and "F" terminals.

This picture shows the carbon build-up inside.

I cleaned the inside with compressed air, then gave it a wash out with kerosene. Let it dry overnight before continuing.

Upon close inspection of the wire connected to the "A" terminal, I noticed that one large bundle of strands was loose, and appeared to have been shorted to the brush holder.

I replaced the terminals, but was unable to connect the wires to them by conventional soldering. I don't know how it was done at the factory, but after a session of I decided to afix copper strapping to the ends of the terminals. I used copper pipe hangers, drilled a 1/4" hole to fit over the split stud, took a cold chisel and cut a cross notch, and tapped it with a hammer to secure the strap. I then tinned the inside of the copper, wrapped it around the wire and soldered. I made sure that there was a gap between the wire, the strap, and the brush holder.

I cleaned the armature and commutator, installed a new sealed bearing in the pulley end, inserted the commutator into the S/G, and installed new brushes.

I installed a new bearing in the other end and closed it up.

That's all for now. I will install the regulator and put it back on the tractor later this week and do some tests.

More to follow...

[chazm 413]

Excellent Tread Bob

Now I have a clue to rebuild mine

Chaz

[shorts 182]

nice repair especially the wiring, the factory solders those wires with a transformer set up that is more of a spot welder than solder iron. an old time rebuilder should have the tools but your fix looks good, and if you have trouble with it you can always use silver solder

edit you might want to use either brakekleen or electric kleener instead of kerosene after you used compressed air to clean the parts, I was taught while working on welders, motos and generators that the oily residue would act as an attractant for fine dirt particles. we used to clean cement dust and carbon black out of the welders with a hammer and chisel and compressed air then pressurewash/steamclean the residue, then we would build a low temp oven with a 100 watt lightbulb and plastic wrap to make a tent and bake the parts for a day or two before recoating the insulating paint with fresh. I know that that old man taught me more about salvaging sows ears into silk purses than I thought was possible from welders on a barge on the bottom of the detroit river to totaled cars to repurposed trucks to salvaged building material.

[rmaynard 15,519]

edit you might want to use either brakekleen or electric kleener instead of kerosene after you used compressed air to clean the parts...

I was told that using such cleaners may have a detrimental effect on the varnish that coats the coil wires. :woohoo: