Farmall Cub

Haven't run my '47 for a while due to carb issues. Got the carb inlet heli-coiled and reinstalled. Didn't have a battery, but with a mag, decided to hand start it. Fired up just fine.

Here's the first question: While idling with the light/charge knob turned to the lowest setting, no noise. When I turn the know to high charge, I get a squealing sound from under the hood (generator). Why?

Second question: I drove it out of the barn after dusk and noticed a glow from behind the dash. I hopped off to find the light dimmer coil glowing at high idle. Is this normal? Or was it because I didn't have a battery installed?

Thanks.

It sounds like a short in the lighting wires. I had this happen on one of my 12 volt lowboys.

Are you sure your knob is pointed right? It can be put on the switch in several different positions. All the way to the left is Lo charge, next to the right is high charge, and 3rd is dim lights, and last to right is bright lights. with no battery, and if you still have a cut out rather than a regulator, turning the lights on will result in having flashbulbs, as Scrivet learned. As Raystractors stated though, you most likely have a short in the wiring and the squeal you heard was the generator belt slipping when you switched it to high charge..

Knob is pointed correctly. Would the generator stop turning if there's a short?

Install a fully charged battery and see what happens.

Eugene wrote:Install a fully charged battery and see what happens.

I always liked doing that myself when possible . Or adding a jumper battery to the circuit , just for a little boost .

To continue...

Installed a battery (tested out at 6.11v) and had the same issues: while running (both at low and high RPM), the ammeter shows no charge at Low or High settings and there is a high pitched squeal when set to High. Removed the generator last evening and will take it to a local electrical shop for testing.

Included the wiring diagram I'm going by. Any suggestions?

That diagram would be correct for a pre-regulator tractor. I think you are correct in taking it to a generator shop, but before you do that try with the A lead disconnected, but only do it briefly. If you still get the squeal the generator probably has an internal short. If the squeal is cleared, the short is probably in the cut out relay. I said only do it briefly, because with no load the generator voltage can get high enough to damage the generator pretty quickly.

The squealing sound could be the generator belt. On high charge, the load on the belt is increased because it takes more power to produce more power. If the belt slips enough, you won't get much charging because the generator is slowing down.

My bet is the generator will test OK.

Appreciate your input. While the Cub was running and knob on Low setting, the voltage across the terminals at the battery was 6.05v. So, even on Low, it was not charging significantly.

I tried to adjust the belt, but the top bolt of the generator was at the outside end of the bracket. I may have to buy a little shorter belt for the fan, giving me more room for the generator to swing out.

I'll see what the shop says and let you know.

Shop tested the generator and cutout relay and there are no issues; runs just fine--didn't charge me either (no pun intended). So, this weekend, I'll reinstall and see what happens.

I asked the electrician about polarizing the unit after installation, to which he said you don't need to polarize a cutout. Does that sound right?

I suspect Jim B. is correct - your generator belt is too loose and is slipping under load.

After picking up the gen, I also swung by and bought a short gen belt. We'll get that thing hummin'!

Stanton wrote:I asked the electrician about polarizing the unit after installation, to which he said you don't need to polarize a cutout. Does that sound right?

Technically he is right. You don't need to polarize a cutout. You better polarize the generator after it has been tested in an electrical shop. It is the one situation where you really need to.

I would question any advice from him!

You polarize the generator, not the cutout or regulator,and yes, you should polarize it. With the engine NOT running, briefly jumper from the bat side to the gen. side of the cutout. A small spark is normal, and it should be done anytime the generator is removed. It usually does not HAVE to be done, but is a safety precaution to make sure it keeps the correct magnetic polarity.

Looks like Jim was faster than me, but that is normal.