Generator smoke

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Dec 12, 2020 | 05:34 PM

Elmersford

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Generator smoke

I just replaced the engine harness ( from Macs truck parts) and when I hooked up the battery the generator started to smoke a little .
Even without the key on .
I read that I have to polarize it whenever you disconnect the battery, is this true?
wires all look good not sure how to proceed .
any suggestions?

Dec 12, 2020 | 06:28 PM

john jamieson

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From: tucson

I think you only have to polarize a new/never used generator. No clue about the smoke.

Dec 13, 2020 | 05:53 AM

Tedster9

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From: Waterloo, Iowa

Quote:

Originally Posted by Elmersford

... when I hooked up the battery the generator started to smoke a little. Even without the key on. I read that I have to polarize it whenever you disconnect the battery, is this true? Wires all look good not sure how to proceed .
any suggestions?

Sounds a little like the cutout in the voltage regulator is stuck. Here's the pitch: one of the ways an alternator is different than a generator, it will charge at low RPM and has solid state diodes that only conduct in one direction.

A generator on the other hand, uses mechanical relays for cutout, voltage, and current regulation. If the engine is not running or when the idle RPM is low the battery relay cutout opens and prevents the battery from backfeeding into the generator and smoking the windings.

When the generator is spinning fast enough, the generator output voltage exceeeds the battery voltage and the cutout closes and charges the battery. Old school voltage regulators in general are a little tricky and they are often ruined by improper adjustment or "cleaning" of the points by people who don't know what they are doing. Is this an old junkbox voltage regulator installed in your truck, or a replacement regulator, or?

It is not necessary to polarize a generator when the battery is disconnected or reconnected (or anything else for that matter). Where did you read that? Just curious, is all.

Dec 13, 2020 | 07:37 PM

Elmersford

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I figured out the smoke. It was the voltage regulator but it was my fault . I hooked it up wrong when I put the new harness on.
Now I’m back to no spark.
I replaced the coil and solenoid and ignition switch.
Used my meter and have 12 volts at the solenoid but only 4 volts to the coil. This ran before I replaced the points and condenser.
Not sure where to test now

Dec 13, 2020 | 08:03 PM

Tedster9

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From: Waterloo, Iowa

Quote:

Originally Posted by john jamieson

I think you only have to polarize a new/never used generator.

In theory the only time a generator needs polarization is when it has been disassembled and the pole shoes have been replaced. Should have enough residual magnetism from when it was manufactured. In practice this may not be the case. I've heard nearby lightning strikes have made it necessary for re-polarization. Or just stitting for a long, long time, or maybe dropped off a workbench would do it.

Generator polarization is one of those internet tales that gets told and retold over and over so often to the point someone would hafta wonder how anybody even made it across town before alternators came on the scene!

Dec 13, 2020 | 08:10 PM

Tedster9

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From: Waterloo, Iowa

Quote:

Originally Posted by Elmersford

Used my meter and have 12 volts at the solenoid but only 4 volts to the coil. This ran before I replaced the points and condenser.
Not sure where to test now

What brand points & condenser? Where did you get them? Try putting the old points and condenser back in, it is tough to source new manufacture points and condenser that are any good. Make sure there is continuity between the non-moving point to ground, even new or used points can build up a layer of crud between the contacts overnight. No worky no sparky.

Dec 14, 2020 | 09:17 PM

Elmersford

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Points and condenser came from oreilys and are the blue fire ones.
Talked to friend and figured out that the condenser was grounded. The clip on the wire from the distributor was touching the plate under the points. I flipped it over and it fired right up