peavynation

When I first start up the car, voltage gauge reads well above 12, between 12-14V.

After I drove home today, (5 miles on city streets), I noticed the gauge reading closer to 11V.

First picture below are the gauges on statup (after the car had been off for 30min after my drive home), and then I sat there with the engine running for about 60 seconds and I watched the voltage gauge fall (second picture). Does not have a problem starting. Car is a 2001 C4.

Bad Alternator? Hot alternator acting up? Regulator? Dirty battery posts? Other bad connections?

Thanks for the help!

Ahsai

Just wondering if you have resolved this and mind to share. My car is currently showing the same symptoms.

TIA

EastBay

any water in the battery?

Ahsai

Yes. Full of electrolyte. I will test the specific gravity too just to confirm the battery is fully charged.

I believe the battery takes charge normally with an external charger and the battery is only 1yr old. I suspect the voltage regulator on the alternator.

Sabugosa

I've just had similar problems.

I was about to drive to DC (about 300 mi from NY) and the battery was dead. Jumped started it and on way down I did not mind the volt meter. Got to DC, drove around and the volt meter would start at 13V, go down to 12V and even under, and the battery felt low upon cranking the engine. On the drive back, the volt meter thankfully registered 13V all the way. A week later I took the car for a short drive and after a few minutes the volt meter again showed just about 12V.

I must have been unlucky - first time ever that I needed to replace an alternator. This is a 996 C4S '05, 18K miles. The battery was replaced about 2 years ago and it checked fine.

Ahsai

Thanks for sharing your experience. I just put another battery in the car and I know that battery is good for sure. Same symptoms. So most likely the alterntator/regulator.

Sabugosa

An alternator replacement is about 6 hr labor plus parts (about the same); a belt change may be included. Best of luck.

peavynation

Sorry guys, I forgot to post all the pictures I took of this DIY! I was gonna do it in a separate post to make it easier to find, and just never did.

Yes, I replaced the regulator and it's been working like a champ. This was actually one of the easiest alternator jobs I've ever done on any of my cars (save the early old school cars).

Below are some picts, with some annotations. One snag I hit: Porsche, in their infinite wisdom, decided to use a fine-pitched steel machine screw tapped into an aluminum housing with no antiseize. Needless to say penetrant oil did nothing and the screw still broke off. So if not for having to drill out and tap (to a bigger size, to make it easier on me), this would have been a real quick job. Still, it only took me about 3 hours, which isn't bad for a first time that included the time to drill and retap the back of the alternator housing. I could do it in about an hour next time if I really boogie.

There's also a REAL good DIY set of picts and instructions and regulator ID info on Pelican, and the author of that is super nice guy that sent me a spare regulator he had for free. He's a rockin dude. He is also the one that pointed out the trick to getting the rear bushing unstuck! That would have really slowed me down to try to figure out.

Ahsai

Excellant photos and info! Thanks a lot!

I'll attempt the DIY if it's not covered by my extended warranty. Will bring the car to the dealer this week and see what they say. BTW, with the new alternator, does your voltage always read between 13-14v most of the time whenever the engine is on?

peavynation

Pretty much, though it does fluctuate a bit between those values depending on hot/cold, lights on/off, combination, etc.

Ahsai

Thanks!

peavynation

gota911

Peavy,

Nice write up!

Chris996

I just got a rebuild and took less than a hour to install.

Ahsai

Just an udpate. The alternator was indeed shot. Dealer replaced it under extended warranty. Now the voltage reads between 13.5v to 14v. It's 14v right after starting (to charge the battery) and it's tappered to 13.5v after a while (when battery has been recharged). It holds 13v even when ALL major power sucking electronics are on (e.g., low beam, rear defroster, and heated seats).