108 generator
 

I noticed my generator sparking at the outboard terminal while I cranked it (and it wouldn't start), and when I went to inspect it I noticed the body of the generator rotates freely (just an inch or so) while the front end plate where its mounted does not move. IOW the seam seems to have seperated. Once I moved it the engine started and it stopped sparking. I'm guessing this is still an undesirable state of affairs, but I don't have any C-notes laying around for a new generator.

There are 2 long bolts that hold the generator together. There are indexing pins on each end. Are the bolts tight? Maybe take a picture so we can see what's going on.

Assuming you have the same or similar Delco Remy Starter/Generator as I have in my 100. Maybe these picture will explain what Alvy said about a pin. I happen to have just taken mine apart today for new bearings and brushes.

There is no way that the body should be able to rotate around the two ends if the pins are still there. I guess in an extreme case if the two longs bolts were very loose it could happen but hard to imagine it would still work.

Here is what the other end looks like. Note that the pin is on the end cap and the body has a slot for it to fit into.

Mine is similar to yours, possibly the same one. Mine was only rotating on the forward end of the generator, near the pulley. I found one of the long bolts and tightened it, and now its snug and the rotation stopped. I might have lost the other bolt, if there ever was one. I see a vacant hole where it probably should be.

I wonder if my brushes are about due for replacement.

I have rebuilt about 4 of these Delco Remy S/G over the last few years and they are pretty simple. The kits on eBay run around $15 and include the two bearings or bearing and bushing for the older ones, brushes and new springs. I did have one that would start but not charge. I took it to an automotive shop that works on alternators and generators and he found that the armature was partially shorted. I was surprised I didn't think it would work at all, but replaced it all was good.

A problem I have had for a long time is an apparent loss of charge between uses. I have checked everywhere for shorted wires, replaced the battery and always disconnect it after use, but the problem remains.

It sounds to me like you have a component bleeding to ground. Not a lot of stuff to deal with. I guess I would start with the S/G first seeing you say it's loose. There might be a connection internally shorting to ground.:bigthink:

Have you measured the battery while running? Normally a battery will be at about 12.5 V when sitting there if you measure across the + and - posts. While charging it should be something higher than that, preferably over 14, but I have some that only charged at 13.5 or so and never had a problem. If while running you are only at 12.5 or worse lower as in discharging you should at a minimum open it up and see if it needs brushes and cleaning or if you have bad luck you may have the problem I mentioned. When you open these up unless rebuilt recently there is a lot of black powder, I guess from the brushes. I always use compressed air to blow out both the inside of the housing but also the armature assembly. I am always amazed at how much comes out.

When you open the S/G you will most likely find that the brushes are worn quite small by comparison to the new. If you are lucky a good cleaning and new brushes might solve your problem. I hope I am wrong but I tend to doubt it. I would think if the brushes were that bad it would not start.

But of course your problem could also be the Voltage Regulator. You can check the voltage out of the S/G on the field post to see if it is generating anything. If so next step would be VR. I would definitely do this before removing and dissembling the S/G. This all assumes that all your wiring is intact.

Your service manual should have the procedure for checking these things I have mentioned.

Real basic, but charging circuit goes from S/G through VR back to battery. That is not a point to point description just the logical.

I have never worked on a 108. My comments are from my 100 and several old JD round fenders that had the same setup. So if I have mis-spoken about your particular model ,I apologize.

First off, what does "IOW" mean?

Lets see if we can at least find out what the problem is with your charging system for little to no cost, so you know in what direction you need to proceed.

Since you say "I have had for a long time is an apparent loss of charge between uses". I'm guessing that you need to use jumper cables or a boost box to get it started. If you disconnect the battery between uses and it's dead when you try to start the tractor the next time, chances are the battery will need to be replaced. Replacing a bad battery could cure the whole problem, but we can move on to the S/G to find out if there are problems there.

If you don't own a multimeter, you can get one from the harbor freight for 3 or 4 bucks if you catch them on sale.

Turn the knob on the meter to VDC, with the battery disconnected in the tractor check the voltage across the pos and neg terminals. It should be 12.5 volts or a little more. Write down or remember the voltage.

Now lets find out if the S/G is capable of making electricity. Since we don't know if there are any wiring issues, remove both wires from the S/G so that it is completely isolated from any problems that could exist (take note of the location of each wire). Remove the belt from the S/G pulley.

Clamp your jumper cables or whatever you use, to the S/G. Pos cable to the "A" terminal, do not clamp the cable to the threads on the "A" terminal, clamp it to the nut.

Clamp the other end of the jumper cables to a known good power supply. Pos to Pos, Neg to Neg.

THEN clamp the other Neg cable to a known good ground (I normally use one of the S/G mounting bolts). The S/G should spin pretty fast.

With the S/G hooked up and spinning, briefly connect a wire to the "F" terminal on the S/G and the other end to a known good ground. The S/G should slow down but not stop completely.

If it does not slow down during this test, try it a couple more times, you may not be making good contact somewhere.

If the S/G does not slow during this test it will need to be rebuilt or replaced.

If you need a different S/G, try putting an ad in the wanted section. Since Minnesota is a Cub Cadet rich state, hopefully a kind hearted member close to you will sell you a good one for a reasonable price.

If your S/G does slow during the test, it is working as it should. Put an ad in the wanted section and maybe a kind hearted member will sell you the other long bolt that holds it together.

Once you find out if the S/G is good or not, post back here and tell us what you found out and we can move on to the next step.