Question for the automotive electrics experts
 

I'm having a problem with the 6v generator in my Type 3 Karmann Ghia; the generators keep dying and I don't know if it's a problem with the "car" or a problem with the generators. I've had 2 generators self-destruct. When I first install them, I got a lot of sparking from the brushes, and eventually one or more elements on the commutator let fly. I have never, ever seen this happen to a generator before. When the generator was sparking, I was still getting voltage, but once the commutator destructed, I didn't, because it kicked the brushes out.

Any idea what would cause this?

http://forums.pelicanparts.com/uploa...1370363664.jpg
http://forums.pelicanparts.com/uploa...1370363683.jpg

There is still an external regulator right? Maybe an internal short to ground? I don't play with many 6volt generators...

Never seen a commutator with a section missing like that. How are the brushes supposed to bridge that? I can see it wearing out super fast. Or is that the problem, the commutator is breaking apart?

IIRC when brand new a generator has to be polarized...

Other than that, the voltage coming from the generator is not consistent, so it goes generator to regulator to car electrical system. Adjusting the regulator depends on exactly which model you have, but on my 356 it is a matter of slightly bending one contact to increase or decrease gap.


Here's a test process from Joe Leoni, an expert in 6v 356 electronics which shouldn't be too far off your Ghia 6v electrics...

Byron; a quick check of the generator is as follows;
Brushes are of adequate length to touch the commutator.
Brush springs have life.
Bearings are fresh and lubricated, armature turns easy. Use
grease sparingly, and force behind the balls. Just a tad of
axial freedom should be noted, to allow for thermal growth.
No burn marks on commutator. Comm should have a nice brown
film. Drop the fan belt.
Ground the DF terminal at the generator, apply a ground to
the D- point, and then touch +6 volts to the D+ terminal.
The generator will run, then lift the ground from DF and the
generator (motor) will speed up. On speeding up, this is an
indication that the fields are working. No fields working,
no counter electromotive force, and armature current
increases allowing the motor to speed up. Just running
without checking the fields is only half of the job. Good
luck, Joe 356 Electrics It's in the books.

Byron; to test the generator while the engine is running
requires a voltmeter.

Connect the D+ lead to a voltmeter and the other voltmeter
lead to ground..
On the DF terminal land a short piece of wire.
Start the engine, voltmeter on, now touch the wire hanging
on DF to ground.
The voltage will jump up to about 8+ volts at 1200 rpm. If
nothing happens, no voltage, flash the field by running it
like a motor as described in step 1. If it still won't
build up voltage, the fields are probably reversed.
Joe 356 Electrics

OR you could put the generator and regulator together in a small closed box so they can get friendly first.......................

When the commutator blew, the idiot light came on, and I replaced the generator (2x). I got about 75km or so on each of them, with a certain amount of idling/fiddling around time.

The generator was supposed to be polarized when I got it, and since it charged for a while, I assume it was.

After the last one failed, I replaced the regulator, out of spite.

From all the sparking I'd guess lots of current. Is the battery OK?

Battery is fine; one generator failed with a brand new traditional battery, the 2nd with an Optima

I believe you need to polarize it when you put it in the car, before hooking up the fan belt.

Umm, can I see a pic of the whole car please?

Unless this is a national level concours winning K-G, I would do a 12 volt conversion with an alternator and all associated 12v items. Many years ago a neighbor of mine named Kerry used to rebuild 3 or 4 K-Gs a year and he always used 12v electronics to eliminate the 6v hassles. He was the guy that introduced me to Garage Los Ponchos in 1980 as he got all his body and electrical work done in TJ. They had an alternator that looked like a stock generator and voltage regulator looked stock too.

could it be that bosch quality these days is in the toilet?

Nowhere near concours, but it's going to stay 6v

http://images.thesamba.com/vw/gallery/pix/1069204.jpg

http://images.thesamba.com/vw/gallery/pix/1069504.jpg

Wow, great looking car.

Type 3 motor with a single carb? Havent seen one of those before.

Type 3's used the 32 PDSIT side-draft carb until 1964. This is a fairly early engine, with all of the correct early parts, which is rare in and of itself. This is actually the original engine for my 1962 T34; I'm running it in the '63 until I get its engine build.

Here's 2 of my Karmann Ghias side-by-side

http://forums.pelicanparts.com/uploa...1370388331.jpg

Have you been using Autolectrics up in Campbell to fix the generators?

Invisible Glass | InvisibleGlass.com

No, I'm using a guy in Monterrey