Here's a tough one...regulator, alternator?

Porsche9xxlover · 10-17-2005, 05:53 PM

O.k. guys, I have a long one here and need some advice/help:

Four weeks or so ago I noticed my battery/alternator light on my 1983 911 SC start to flicker at a light...I pressed the throttle and it went away...that was it. The car then sat for three weeks until I drove it two nights ago. I went out w/ my wife and after a party, we got in and started it up...the light started to flicker again and my radar detector wouldn't turn on. A few minutes later, the detector turned on! Kept driving...

Thirty minutes later the light went on again...and at a stop light I put on my turn signal...when I did this, the TACH WENT NUTS!! Bouncing over 6k and back to 1k etc. It stopped doing this when the signal turned off.. As I drove, my int lights dimmed and the radio shut-off. I went into my driveway and put on my hazzards and the engine died and would not restart!

I waited until the morning and checked my four year-old Porsche battery...very dry! I added almost six cups of water and it started right up! Now, after 30 minutes of driving, I turned it off and it would not restart.

Put it on a trickle charger for seven hours...now fully charged; started up and then started again a day later.

HERE COMES THE QUESTION: Went out an hour ago and it started right up but the light is flickering again!!! Not on steady, just flickering! WHAT CAN IT BE? Regulator? Probably not the alternator b/c the car starts fine...? YOUR THOUGHTS?

Could the battery and something else that went/is wrong (alt or reg) just be a coincidence? Interdependent? Thanks for your advice and patience reading this long post.

oneblueyedog · oneblueyedog's Garage

The alternator voltage regulator is probably going out.

I think your car has the VR onthe back of the alternator. If the VR is not on the left side of the engine bay behind the plastic cover it is.

Do your headlights pulsate or get brighter when you rev up? If they just dim then the alternator isn't keeping the battery charged.

DIODES (RECTIFIERS) OR VR OR BOTH. I'd replace both since I think they are interdependent.

It's a possible DIY, but difficult getting the individual pieces if you are not a rebuilder.

Go with a new one from our host.

Check the cheap stuff too, like battery terminals and clean all the ground terminals.

JTL · JTL's Garage

This sounds exactly like what happened to me on day 2 after buying my first 911 8 years ago. The first diagnosis has a cooked battery but the problems continued. They ended up pulling the alternator and found some diodes had gone bad. I do remember the headlights flickering a little.

jt
-84 targa

Tigerrat · Tigerrat's Garage

Based on my episode with my '88, I'd sure say VR. It can exceed the proper voltage output and "cook" the battery. Ken

1982911sc · 10-17-2005, 09:53 PM

Classic Voltage Regulator....which on your car I believe is imbeded in your alternator....on the top, you will have to remove the fan, and get to the alternator which lays behind the fan housing....Take out the alternator, pry out the old VR and replace with a new one...you can do this yourself...I did...it took about about two hours or so start to finish...you can buy the VR here at Pelican....this is a very common issue with these cars. Good luck.

1982911sc · 10-17-2005, 09:55 PM

oh by the way it cooked my battery! Good excuse to buy an OPTIMA!

88911coupe · 11-22-2010, 10:19 AM

OK, trying to figure out if I have a VR problem too. 88 3.2 just rebuilt engine and while it was out had the alt. rebuilt. Now about 3k miles later I'm getting the alt. light coming on at stops and idle, goes off at 1500 rpms. Battery shows about 13.2 while car running.
Is this possibly the VR...?
I'm out of Town (Tulsa) so may need to see if I can drive for 3-400 miles back to Dallas with this going on or should I make sure and get it fixed here now.
TIA

joecrum · 11-22-2010, 12:09 PM

I just replaced my VR due to similar issues as yours. Everything is good again. Start with the VR (it's much much cheaper than the alternator). It took me about 45 minutes to replace it.

88911coupe · 11-22-2010, 12:23 PM

VR should be at the local indi P shop by 9 am tomorrow, plan to get everything apart tonight and hopefully that solves the problem.
Issue is most of my tools are at home so will probably take a lot longer than normal.

Bob Kontak · Bob Kontak's Garage

Quote:

Originally Posted by 88911coupe

Issue is most of my tools are at home so will probably take a lot longer than normal.

There may be a torx fitting on the v reg - You can cheat with an allen wrench.

wwest · wwest's Garage

"..battery..very dry..."

Overcharging the battery will boil away the electrolyte within just a few days. Surprised you didn't smell it.

steely · 11-22-2010, 07:05 PM

Consider that high V spikes may not be good for the DME.

tcar · 11-23-2010, 12:24 PM

Quote:

Originally Posted by Tigerrat

Based on my episode with my '88, I'd sure say VR. It can exceed the proper voltage output and "cook" the battery. Ken

Can also 'cook' your wiring... start a fire, worst case. Can burn out bulbs.

theiceman · 11-23-2010, 12:48 PM

This is not a "hard one "at all

take your alternaor out .. send it out to have it rebuilt and make sure they put a good regulator in it . Not a chineese one .Replace your alternator bulb in the dashboard while the alternator is out , put it all back together with a new battery and clean and tighten all grounds.. done ..

dshepp806 · dshepp806's Garage

Quote:

Originally Posted by theiceman

This is not a "hard one "at all

take your alternaor out .. send it out to have it rebuilt and make sure they put a good regulator in it . Not a chineese one .Replace your alternator bulb in the dashboard while the alternator is out , put it all back together with a new battery and clean and tighten all grounds.. done ..

+1?

Doyle