I have a 239 in the truck, (50 F-1), but it is not wired up. I have it hot wired just to be able to start the motor. My question, how can I check the generator without the motor being wired up? I have the generator mounted and the belt will spin it but I do not know how to test it.

 

If I inderstand the question correctly there are some limitations on what tests can be performed. The generator can be "full fielded" as a general test for voltage output, but that's about it. Connect a jumper wire between ARM and FLD terminals at the generator. Connect the analog voltmeter between the ARM terminal and GND terminal. Run the engine only long enough to measure the voltage, it is unregulated voltage output connected this way and would be damaged if prolonged. I'd have to look it up, but if I recall the voltage should spool up pretty high, maybe about 19 or 20 volts in a 12 volt generator. Probably depends on RPM.

As a practical matter the generator should ideally already have fresh bearings and commutator sanded bright, mica undercut, fresh brushes installed and sanded to conform with the shape of the commutator. If you have a nearby motor rewinding shop that's been around a while, think about taking the regulator and generator in together and they can spool them up on a test set and make sure the cutout, voltage, and current voltages are correct. I like to pair a NOS or good used regulator with a rebuilt generator. Some careful attention to detail seems to take the hair shirt element out of these old beasts. They are not "maintenance free", this includes the regulator too.

 

back in the old days we just hooked it up to 12 volts and if it runs like a Motor then ya call it Good

I'm sure you all know about Flashing the Fields

EDIT: If it will Motor then it will Generate......

 

I know that can be done with permanent magnet motors, but how do you connect the wires on the generator to motor it?

 

connect the Armature Terminal to the Field Terminal then apply voltage to the Case of the Genny and to the AF connection depending if positive ground or negative Ground to what battery cable you hook to the case.... if it's negative Ground then Negative to the case and Positive to the AF jumped connection and it should run as a Motor... it don't matter which way you connect the + and - but it will polarize the Fields in the direction of connection so is best you hook it up for the way you plan to use it.


While it may not be a Definitive test of Generator Current Output, it does verify Commutation .....
you can also note Brush arching and get an Idea of Armature condition... Heavy arching indicates armature windings are not so good.

 

hey I just searched and MOSS Motors has a video... I use Moss for many of the old MG's that I work on...

 

It takes a little judgment on the motoring thing, it will generate if it spins, but a good generator will motor pretty fast and smooth, not slow and lumpy. If you're gonna run a generator, "do it right". Take it apart and clean it up, inspect the brushes, check for burning, replace the brushes. Don't set yourself up for failure, they will burn up pretty quick when things go sideways.

 

Heavy arcing indicates: 1) Worn / dirty commutator surface. 2) Mica is protruding and needs to be undercut. 3) Commutator is out-of-round and needs to be turned. 4) Worn / badly seated brushes. 5) Poor brush spring tension. 6) Overloading. It should also be observed if the arcing is leading or trailing the brushes, or both. The cumulative effects of these symptoms could lead to a flash-over, and then you have copper and solder all over the place.

 

I believe those radio-suppression capacitors installed at the ARM terminal, at both the generator itself, and at the regulator, may help reduce contact pitting and maybe increase brush life somewhat. The ignition condenser has a similar purpose, as well as optomizing spark energy at the plugs.

 

I have a 6 volt system but did as instructed and put jumper wire on and checked with voltmeter and nothing. Another stupid question, I have the engine hot wired,( jumper wire from positive terminal to positive terminal of the coil, negitive ground) and it starts and runs well. I got the wiring diagram for the motor and it shows positive ground. Which is correct? Also if I turn the connections around make it positive ground will this damage anything?

 

It helped considerably!!

 

OK. Through an extraordinarily unlikely remarkably improbable series of events, it appears I have made a mistake. Yeah. Tough to believe, I know. /s

The test I mentioned, a jumper across ARM and FLD, is for the generator output test.

Current, not voltage.

Need a 0-100 ammeter or one capable of measuring at least 30 amps. You may not have this in your toolkit, I don't know. It is an important test, too. In all cases, these kinds of tests, to test the output of the generator on the truck, assumes that every bit of wiring has been removed from the generator/regulator. "Full fielding" the generator for testing voltage involves grounding the FLD, though don't quote me on that. Not finding that in the manual.

Be sure to follow any testing procedures, either the generator or regulator or both, using ONLY the procedure for FORD or "Type B" generators. A lot of the tests available online or in books are different, because other generators were wired differently. If you use the polarization or test methods for a Chrysler or GM or something Uncle Buck used to do on his Stude, you risk letting the magic smoke out.

You may decide installing a 1 wire alternator is worth it for you. If you want to use the generator, you'll have to study up a bit.

 

Don't worry about making a mistake, I only make one mistake a day, that being getting out of bed!!! I apricate the attempt and info.

 

Basically, grounding the FLD momentarily should result around 18 to 20 volts DC when spooled up.

I'd still want to clean everything up and inspect it before putting it into service. It's literally 2 bolts to take it apart. The rear plate used to be available as an assembly, to make servicing and installing new brushes easy. Could be done without removing belts or generator from engine. There is also an easy test to check for shorts or open windings in the field coils.

 

Went ahead and bought the rebuild kit for the generator if I am going to open it up, I might as well rebuild it. Thanks for the assist!
I have the 239 hot wired,( wire from the positive side of battery to positive side of the coil) just to run it, and this would be a negative ground system. The rewire guide that I received shows the system to be positive ground. Which is correct???