New alternator not charging!

[TerryBPP]

Thanks for all the help John.

[Lorenfb]

Where did you find such a klug (mickey mouse junk) for an alternator?
I've never seen such a "thing" to be installed a good Porsche in 20 years.
No wonder it doesn't work. You should have had the original one rebuilt
and left the system stock.

Get a refund on your money and rebuild the original!

Good Luck
Loren
'88 3,2

[Early_S_Man]

Terry,

Your old and new alternator actually do look quite similar!

Your old unit looks like a 980 Watt Marchal/Motorola ... and the new one looks like the Marchal's that Stoddard's used to sell that were converted to an internal regulator. Quite superior to the Paris-Rhone or Valeo alternators, actually, if you value reliability!

[TerryBPP]

Loren, I got if from Pelican Parts so watch your tounge. They could be listening.

[TerryBPP]

Hey john, when I touch the blue wire to the engine should the key be on or off? I looked all over for the external regulator and still can find it. Are there any weird places people have found theirs? Its definitly not on the drivers or passengers side fenders.

[304065]

The ignition should be in the "on" position.

Man, this is getting strange! Follow the black wire that comes out of the fan shroud. It should go to the external regulator.

More specifically, where the hell does that black wire go? Trace every inch of it. It goes through a rubber grommet in the engine cooling shroud, into a wiring harness that's wrapped in black electrical tape. At the other end, it goes into a 14-pin connector that connects to the electrical console.

Inside the console, there's another connector, and wires come out of that and go to the four-pin plug for the voltage regulator.

The voltage regulator is a rectangular metal can, with a metal flange on it that has two holes in it, that screws to the console. It should be white? and say something like Marchal or Motorola on it. Some joker might have fitted a Bosch, which looks like a metal can with a piece of tape (either white or yellow) around the end, but that's the wrong maker VR for your alt.

Anyway, if somebody has fitted an oddball external regualtor, it will probably look like a plastic or metal box, and say something like "Huco" or "Bosch" on it. There should be wires going into it.

Do you have a digital camera, you could take some photos of your car and upload them?

[TerryBPP]

I have a diggy. I take some pics this weekend. I'll see if the blue wire grounds as well. Thanks again.

[Early_S_Man]

Terry,

The Marchal regulator for a 980 Watt Marchal alternator like yours has a Black or Gray plastic cover, rectangular in shape, with metal mounting bracket ... and should be bolted [plug down] to the 'console' on the left side of the engine compartment in between the fuse block and the CDI-unit. It has a 3-pin plug that may or may not have a RFI-suppression module connected in-line with the harness connector.

In the pic below ... the device between the Gray and Black regulators is the RFI suppression module.

[TerryBPP]

Thats the first place I looked. The PO installed a Crane CDI box and did some half a$$ wiring. The only thing on my console is the CDI, and a fuse box with 1 relay. I searched everywhere for that thing.

[TerryBPP]

John, you were right. The bulb was blown out. Now the bulb won't go out. I checked to see if the alternator was ground properly and it was. Does the light take time to go out?

BTW: still haven't found the VR!

[Lorenfb]

Addition Note:

The alternator with the klug for an internal
regulator has the wrong set of diodes. The diodes
are pressfit diodes on an aluminum plate. As the
plate heats up, the diodes fail to make contact.
These pressfit diodes where OK on the 55 amp alt.,
but not the 70 amp. The diodes should be soldered
to the heatsink plate as in the original. The early
928 alt. has a similiar problem.

As I said earlier, have the original alt. rebuilt with
the correct diode plates.

Have Fun
Loren
'88 3.2

[TerryBPP]

Anyone!

[304065]

All right, now you are getting somewhere.

The light is on because current is flowing from the battery through the light to the alternator to ground. Think of the voltage in the circuit as the pressure in a hose. Current flows from the higher pressure to the lower pressure.

When the alternator is putting out voltage, the "pressure" is equal on both sides of the bulb. 12v from the battery and 12v from the alternator. With no potential difference, the current doesn't flow and the bulb goes out. Make sense?

As long as the light is on, you don't have a voltage coming from the alternator.

Theory lesson over, now let's fix the problem!

I don't understand how you could have a working electrical system without a voltage regulator. Why did you change the alternator in the first place? Did the car ever run for long periods of time without having to charge the battery back up?

We need more history here, something is wrong. With no VR to be found in the car (I assume you looked EVERYWHERE) we have to assume you had an internally regulated alternator. But that's not consistent with the picture you posted, which is clearly of an externally reg'd one. The new one looks like it has an internal regulator, but you can't tell that. Have you tried unscrewing it? The brushes are in there, if you take it apart to verify that it's an internal reg, be sure you can get it back together again.

I would tell you to put the new alt back, connect everything like you originally said, forget the black wire and go, but not knowing how the car is wired, or whether there's an old VR hiding somewhere, that's not the best advice.

If you car ran fine before, I would say, send the alt back to where you got it and source a rebuilt externally reg'd one.

Sorry to not be more help but without actually being there that's the best I can offer. Good luck.

[TerryBPP]

Ok, the car has run flawlessly for the last year and a half. One day I accidently left the lights on and completely drained the battery. After that the car would start but not stay running. The lights would dim and finally it would die. So first I replaced the battery with a Optima Red Top think it was the battery. Of course the car ran with the new battery but the post voltage was steady at 12 V and would not go up to 14V. After a day the new battery was drained. So at that point I concluded it was the alternator. When I got the alternator out of the car it looked like crap. So that backed up my thought that it was the alternator.

A smart man would have had the alternator tested before he bought a new one. But I figured it needed to be replaced reguardless.

As far as the VR goes its possible its hidden in some crazy place. Since its no longer connected to the alternator it shouldn't matter right?

[Early_S_Man]

Terry,

Unless the wiring for the regulator was taken out of the 14-pin connector and spliced AND run somewhere else ... the Brown, Black, and Blue wires to the regulator must go thru the 14-pin connector and lead to the regulator!!!

If you disconnect the battery, it is perfectly safe to unbolt the fuse/relay/CDI-unit plate/console and examine the wiring on the underside to look for the missing regulator wiring ...

[1fastredsc]

Does that resistor upgrade thing done to the back of the warning bulb work also with my sc electrical or is my electrical different? (sorry to intrude on your thread BTW)

[304065]

Your '83 SC should have come from the factory with a four-watt bulb for the alternator warning light. It's a larger diameter than the smaller 2W bulb. Therefore, your car does not need the resistor.

However, you may want to see Warren's thread in the archives where he talks about installing a resistor across the terminals in parallel to lower the "zero-ampere" speed of the alternator.

[1fastredsc]

I did a search and couldn't find anything, unless by archive you mean something else.

[304065]

Alternator question