Need to test and rebuild alternator

asgi99 · asgi99's Garage

It looks like my alternator is shot. Can anyone recommend a shop in the San Francisco area that can test and rebuild? Or may be somewhere I can send it.

Thanks

NEW911SC2 · 01-23-2007, 08:45 AM

If you have a Bentley manual and a simple voltmeter, you can follow the procedure and check the alternator yourself. It's pretty easy.
Also, assuming that your battery is good, another quick test would be to turn the car on and, while it's running, disconnect the "negative" battery terminal. If the alternator is good, and holding the charge, it should stay on. If it dies when you pull the cable, then the alternator is no good. Hope this helps.

asgi99 · asgi99's Garage

'If it dies when you pull the cable, then the alternator is no good. Hope this helps.'

How do I determine if the alternator dies?

NEW911SC2 · 01-23-2007, 09:19 AM

Sorry about not being clear. If your alternator is bad, when you pull the negative cable, the your engine will stop running.
If the alternator is good, when you pull the cable, the car will continue running because the alternator is holding the charge from the battery. If you determine that the alternator is good, replace the cable as soon as you can. It's not good to run the car like this for too long. It's a quick test but it should answer your question. Good luck.
PS- Don't forget to tighten the cable terminal when you're done. Hope this helps.

asgi99 · asgi99's Garage

Great, many thanks will check tonight.

jmohn · jmohn's Garage

Quote:

Originally posted by NEW911SC2
Also, assuming that your battery is good, another quick test would be to turn the car on and, while it's running, disconnect the "negative" battery terminal. If the alternator is good, and holding the charge, it should stay on. If it dies when you pull the cable, then the alternator is no good. Hope this helps.

This is a very bad idea. Do not do this. Do a search for trouble-shooting the charging system.

I repeat do not disconnect the battery while the enigne is running.

Jerry M
'78 SC

asgi99 · asgi99's Garage

So I already did what I could do to troubleshoot. The problem I have is that the idle is erratic, the alternator light is not working and the battery is discharging.

I ran a wire from the alternator light back to the alternator outside the car and it's still not working. So at this point I am assuming that the alternator needs to be replaced. Is this a correct diagnosis? I had wanted to get the alternator checked when I got it repaired to confirm my diagnosis.

Mahler9th · 01-23-2007, 10:45 AM

There is a great place down in Campbell, CA that offers service and sells rebuilt alternators of all kinds. They are right near Sportech, which is a Porsche repair business, and Jerry Woods Enterprises/Smart Racing Products. ALso nearby is the Ferrari dealer's service department. So if you head down there, you can check out some eye candy. Once I went there to pick up some stuff and they had an Enzo, a bunch of 355 Challenge cars, and a Mercedes race cars from a few years ago (the one that beat up on the Porsche GT1's pretty good). And of course there was ample Porsche engine and historic race car eye candy at JWE/SRP.

The price for a rebuilt alternator is very low compared to all others I found, and they can test yours. I will try to look around for the name/phone number. I think they may be in the yellow pages too. Try 408-559-3540. This place even had the elusive nut needed for the type of alternator used on my engine. It was extremely expensive from Porsche, and they had them for a buck or too (they have them made).

- Mike
PCA Golden Gate Region
Porsche Racing Club

cbeers · 01-23-2007, 11:18 AM

I recently used Riteway electric in SF. Good job, great price, one day turn around. A fellow Pelican set me up with them.

I think the guys name at the shop is Jeff.

-Chris

cak · 01-23-2007, 02:49 PM

Name: Pacific Auto Electric
Address: 105 W. Weddell Drive
Sunnyvale, CA
Phone: (408) 734-1482

They've been in the rebuild business (at the same location!) since the 50s, have seen it all, do great work at fair prices. Highly recommended (they just dealt with my dead alternator).

NigelJ · 01-24-2007, 09:11 AM

Hi asgi99

I am pretty shure that if the alternator light is broken then the alternator will not charge as the current to excite the coils in the alternator is supplied via the bulb. That is why it glows when there is no charge. A broken bulb opens the circuit.

Try just fitting a new bulb.

Cheers

NigelJ

asgi99 · asgi99's Garage

Thanks. Tried a new bulb, running a wire directly from the bulb to the alternator and still no joy. Going to run over to Riteway in a couple of minutes. Thanks for all the help everyone - will let you know how I get on.

asgi99 · asgi99's Garage

Just got back from Riteway. Alternator was shot. Teach me to buy a cheap one off eBay last year. Cost for a recon is $195 incl. tax ($75 more if you don't have the core to exchange). Its the same price for an exchange as for a rebuild of your core, except if they rebuild there is no tax. Here's the address,

261 6th Street, San Francisco
415 882 4444
http://www.rite-wayelectric.com/index.html

cbeers · 01-24-2007, 11:06 AM

Well, glad that worked out for you.

That price seems a little higher than I just paid, but close. I also brought my housing in for a small repair and in that process, it was blasted clean too! I think the total for everything was about $225ish, but again, that included work on the housing which was cracked.

-Chris

Soze911 · 03-04-2008, 10:19 AM

When doing the 'wrong' test -removing the ground cable from battery; should the engine die right away if the alternator is bad?
I was told by the sears technitian who replaced my battery that the alternator was bad. I got home, disconnected the negative cable from the battery, and the engine ran for about a minute or so then the RPMs went all over the place until it the engine died.
I reconnected the negative cable, turned the ingnition and the engine started right away.
The reason I went to sears for a battery replacement is that the battery was not holding charge anymore, I jumpstared it in the morning, drove it for about 12 miles to Fry's electronics and after maybe 40 minutes when I came out of the strore, the car would not start.
can it be something else other than alternator?

R2911 · 03-04-2008, 11:43 AM

Just recently bought a rebuilt alternator for my SC from these guys. Very reasonable price.
Don't have their phone number available, but you could probably Google them.

Alternators Unlimited
San Pablo Ave.
Berkeley, CA
Contact: Sal

rusnak · 03-04-2008, 12:06 PM

I have a mental note filed away that says "do not disconnect the battery cable when the engine is running or you can damage the diodes on your alternator". Use a voltmeter, check the battery voltage when the engine is stopped vs running.

Soze911 · 01:11 PM

I failed to read this forum before doing such test. It is done however. The question is: If the negative cable from the battery is disconnected while the engine is running; should the engine stop immediately after disconnecting the cable if the alt is bad?
I have an alternator on hand -or somewhere in my garage rather- so getting the part isn't really the issue. I'd just rather not remove the alt in the car not knowing (or having a high degree of certainty) if it is bad or not.

Engine off (not running) 12.3V
Engine Iddling (@<1000rpms) 14.1V

Do these number look ok? I just drove the car for about 40 minutes total, not continuously but almost, and I couldn't detect any problems. How much weight should I put on the Sears disgnostic results?

Chris Tallon · 10-09-2008, 02:05 PM

I need to have my alternator rebuilt or exchanged. Is there a good place in the Los Angeles area that I should use?

Thanks in advance for any assistance.

911pcars · 10-09-2008, 02:47 PM

Quote:

Originally Posted by Soze911

I failed to read this forum before doing such test. It is done however. The question is: If the negative cable from the battery is disconnected while the engine is running; should the engine stop immediately after disconnecting the cable if the alt is bad?
I have an alternator on hand -or somewhere in my garage rather- so getting the part isn't really the issue. I'd just rather not remove the alt in the car not knowing (or having a high degree of certainty) if it is bad or not.

Engine off (not running) 12.3V
Engine Iddling (@<1000rpms) 14.1V

Do these number look ok? I just drove the car for about 40 minutes total, not continuously but almost, and I couldn't detect any problems. How much weight should I put on the Sears disgnostic results?

Those numbers appear okay. The alternator is creating more voltage than the battery, thus the battery should charge. Perhaps you have a malfunction in the electrical system that discharges the battery overnight.

Sherwood