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sethkestenbaum 11-11-2019 10:54 PM

Generator Motoring / Cutout sticking

I thought I would post about a non-event repair I had to do today. When I got to the garage and switched my battery disconnect switch to "on" I heard a whirrrrrrr from under the hood. You guessed it, I have a sticking cut out and a motoring generator (or at least trying to move the fan belt). I've never had one stick on me, but knew that they could.

I am thrilled:

1) to have installed a battery disconnect switch. Without this added safety feature the generator could have motored when I wasn't near the car and burned out or worse.... heated up too much and started a fire.

2) that all my fordbarn post reading and experiences with the car since 2011 enabled me to diagnose the issue before even opening up the hood. There is nothing else electric under that hood that could whirrrr but the generator (edit: yes, the starter could spin too)and no reason for it to do so unless I had power going through it. The cut out, if sticking, can cause motoring.

3) I happen to have a backup cut out that came with a busted generator I recently purchased. It fit great and only took about 2 minutes to find.

What did I do? Set the battery switch to "off", swapped out the cutout (it took 2 minutes) and ordered a new diode cutout that will to be kept in the car as a back up. After nearly 9 years with the car, this was probably the quickest and easiest repair I have done.

Mike Peters 11-12-2019 09:57 AM

Re: Generator Motoring / Cutout sticking

Seth: I didn't know that a generator could "motor" when connected to the fan belt, the fan belt would keep the generator from turning after shutdown. A stuck cut out would show a big discharge on your ammeter after shutting down the engine, and if not corrected, simply run down your battery? Confused in Sharon.

History 11-12-2019 10:23 AM

Re: Generator Motoring / Cutout sticking

Could the starter make the noise he heard? Turning but not engaged? I was able to get my generator to motor but can't see any way it would do that with the belt attached. I can't think of anything but those two items that could make a noise.

I guess there could be a noise with it trying to spin or,, could the belt be loose enough that it would turn?

sethkestenbaum 11-12-2019 11:14 AM

Re: Generator Motoring / Cutout sticking

It wasn’t spinning well but was trying. It was pulling at the belt. Swapping the cutout “fixed” the problem.

Mike Peters 11-12-2019 11:26 AM

Re: Generator Motoring / Cutout sticking


Originally Posted by sethkestenbaum (Post 1820497)
It wasn’t spinning well but was trying. It was pulling at the belt. Swapping the cutout “fixed” the problem.

OK. That makes sense. We keep our belts fairly loose on Model A's. Thanks for clarifying. Glad you got another cutout that worked.

1931 flamingo 11-12-2019 03:46 PM

Re: Generator Motoring / Cutout sticking

Yes, the starter can make the same type of whirring sound, usually the bendix still turning even with the engine running.
Paul in CT

Mike V. Florida 11-15-2019 11:11 PM

Re: Generator Motoring / Cutout sticking

You would have to open the "can" to see what happened. I for one would like to see pictures of the thing once the cover is off.

sethkestenbaum 11-16-2019 02:40 PM

Re: Generator Motoring / Cutout sticking

Mike, I'll eventually get around to it. I had the back up in my garage and bought a new back up from Brattons that came within 48 hours.

Dodge 11-18-2019 06:58 PM

Re: Generator Motoring / Cutout sticking

I had that happen 50 years ago when I was in school. I got out of the car and shut it off.
The motor was VERY worn and low on compression. As I walked around the back of the
car, it had been left in neutral I could heard the sound of compression coming very slowly
out of the exhaust pipe. I lifted the hood and the generator was turning the motor over
it would move then hit a compression stroke and sit there for a moment then the motor
would turn one cylinder at a time. Ka chuff-------Ka chuff
I hit the cut out with a screw driver handle and it stopped.

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