[OldTee]

Why do Porsche problems have to be so hard to resolve?

When I rebuilt Michelle's car two years ago I installed a new alternator. Electrical problems on top of other problems have plagued that car for some time. Recently I had the alarm system removed and that cured the battery dead headache but in the process of testing I found an interesting problem.

I have a digital voltmeter I plug into the cigarette lighter. It showed an intermittent problem with the alternator. What it was doing was charging properly, IE 14v after start up lowering to 12.4v after a few minutes. The ten minutes into a drive the voltage would begin to lower slowly from 12.4v to 12v then 11v all the way down to 10v. It would stay there for a while and then climb back to 12.4v in steps, only to repeat the process again.

Since the cost of verifying what I am seeing is a nice discount on the price of a new alternator, that is where I am going.

HOLY SMOKE.... What the hell is so special about a 87 Carrera alternator that it should cost $589 at Performance??? That is highway robbery.


ARF

TR do you want another junk alternator with an intermittent problem. Great device to learn how to install and reinstall alternators on 911s.


ARF

[Bubblehead]

Ouch, they're even $420 at Pelican. I wonder if there is an alternative alternator?

[Trak Ratt]

Originally Posted by OldTee

Why do Porsche problems have to be so hard to resolve... Makes us better people

TR do you want another junk alternator with an intermittent problem. Great device to learn how to install and reinstall alternators on 911s.


ARF

You know it might make a neat DIY for tech!

[KevinOyler]

Can you replace the voltage regulator separately on a 87 Carrera alternator?

[Vicegrip]

We can trouble shoot it and repair if repairable. I have replaced only one alt in my life repaired the rest.

[Jase007]

What about a rebuilder ...

Arlington Armature

Or similar in you neck of the woods?

[cmartin]

X2 on fixing yours. Rockauto has a few at a fraction of Pelican's cost if you prefer that route.

[markwemple]

I'm with rebuiling if Kurt can't fix if you know of one that has a good rep.

[OldTee]

Originally Posted by Vicegrip

We can trouble shoot it and repair if repairable. I have replaced only one alt in my life repaired the rest.

This sounds good but I want to do some more tests and inspections first. I talked to Matt DeMaria today and suggested some places to look for trouble. Also he feels an inductance amp check during failure mode might provide some valuable insight. Can I take a rain check?

ARF

[Vicegrip]

I don't work on lectric' stuff in the rain and your money is no good in my shop.

I find that you don't need to go high tech on alts. I take them apart after looking for "Well duh" stuff on the outside like burned, loose or green crusty connectors and the like. As I disassemble I look for worn com rings and brushes, loose or cracked solder connections and at the devices such as the diodes. I do test them using a meter. I look for burnt or damaged wiring and look carefully at the windings after blowing the thing out with compressed air. 99% of the time you can see what has failed. Given the on and off nature I would be looking hard for cold solder joints and other heat related items. some of the health club equipment I used to repair used alts as a load. They would fill up with com brush dust and cut in and out. Blowing them out fixed all kinds of odd symptoms. Automotive format units are much less prone to carbon dust buildup.

I would also not assume it is the alt just yet, is does sound like the alt is a good place to look but it might also be something like a loose connector between the alt and the rest of the car. Take a quick peek at Big Red on the starter to see if it is loose or green crusted