Model A Ford generator
- Thread starter Bob Wise
- Start date
BRENT in 10-uh-C
Well-known member
Disconnect the Cut-out wiring and remove the Cut-out from the Generator. Next remove the fan belt. Using a set of jumper cables connected to a charged battery, connect to the Generator and see if it will spin like a motor. If so, in all liklihood it will charge and therefore consider swapping out and installing a good Cut-out with a diode in it.
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Brent's advice is right on the money but I would like to add a bit of advice if you do have to buy a cutout with a diode. Buy it from a Model A Ford parts dealer and not from a flea market casual vendor. Why do I say that? It is because current goes thru a diode only one way. The Model A is positive ground. The Model T is negative ground, so the diode cutout for the A will not work on a T and the T diode cutout will not work on the A. A casual flea market seller may not know which one he is selling as they look alike.
Tom Wesenberg
Well-known member
Start the engine and set it to a fast idle, then jump across the two cutout terminals. If it now shows a charge the cutout needs the contacts cleaned, or the pull in winding is bad. If the amp guage still shows a charge after the jumper wire is removed, then the generator just needed to be polarized.
Don't run a Model A generator for more than a few seconds if it's not connected to the battery, or it may burn itself up. If the cutout is faulty, then the generator isn't connected to the battery. In case of a faulty cutout, you can safely run the generator by jumping the output post to ground.
Don't run a Model A generator for more than a few seconds if it's not connected to the battery, or it may burn itself up. If the cutout is faulty, then the generator isn't connected to the battery. In case of a faulty cutout, you can safely run the generator by jumping the output post to ground.
Bruce of MN
Well-known member
Is the procedure any different if you have a diode cutout (bought from a major shop)? My gen motors, but doesn't give more than battery voltage at a fast idle and the 3rd brush pushed all the way down.
Tom Wesenberg
Well-known member
Same procedure for the diode cutout. Jump the two terminals with the engine at fast idle, then if it still shows no charge the generator most likely needs to be repaired. Check the voltage with a seperate meter to see if it rises above battery voltage.
Bruce of MN
Well-known member
Thanks, I'll do this.. I always thought that motoring was a reliable sign that the generator was OK.
Tom, you were right on the money for my French-assembled 29 Tudor's side cutout Powerhouse generator about the polarization. Had a loose field coil that caused a break in the solid wire connection between two of them. Placed a crimp collar across the break and used a pencil soldering torch from Harbor Freight to run some solder down into the collar connecting and stabilizing the break. Motor test off and on the car were fine. No charge when started, however. Had left the back cover off and connected the jumper across the diode cutout I have installed. Some sparks came from the engine side of the back of the generator and I now have good charge level. Believe polarization was the problem. Another one for the mind file of tips and tricks. Thanks for posting here where we novices can find them.
Tom Wesenberg
Well-known member
You polarize the same way with a diode cutout. The amps output should show on the instrument panel ammeter, and if you have the 3rd brush pushed way down, the output should be quite high.
walt jones
Senior Member
Usually motoring a generator provides a good indication that the generator will do its job and generate, but not always. I had a power house generator that would motor fine but when the generator was put in service it would fail to provide sufficant current for charging. A growler test of the armature showed that it had a shorted winding. Hopefuly yours does not have this problem.
All the best,
All the best,
Mike V. Florida
Well-known member
If you apply voltage to a generator it will try to work as a motor. This is the reason for the cutout, it cuts the generator out when the engine is not moving (or moving fast).
If it doesn't motor it is an almost guarantee that the genny is bad. Like Brent says in all likelihood the genny will work. Next step after the genny motors is to follow Toms advice;