Alternator/voltage reg question
 

Greetings,

My 85 has been exhibiting signs of alternator/voltage regulator failure (dimming and brightening of head/dash lights) over the past couple of months. I don't put many miles on it and most are during the daylight.

I've been reading up on the symptom/cure and plan to check the voltage at the battery this weekend to see what's what, and am working up the courage to pull the alternator for a rebuild (assuming that's the issue).

I'm a little concerned about boiling over the battery. Does driving in the daylight (i.e. w/o using the headlights) lessen the risk of this happening? Are there any telltale signs of battery boil? I'll obviously do a thorough check of the battery this weekend when I check for voltage.

Thanks,
Jack

Jack

BTDT http://forums.pelicanparts.com/porsche-911-technical-forum/629141-another-boiling-battery-story.html

My VR when bad after a few minutes of driving, from 14 volts to 17 volts.

Yeah the battery boiled over. It does give out a foul smell that you should smell it in the cabin (even in a Cab). Also the battery wil be hot to touch and you should have sign of spewed acid unless you got a vent tube.

I only find out when I monitored the voltage while riding (voltmeter via the the cigarette lighter).

I picking up a new VR (from PP) tonight.

The battery still shows 12.4 volts but I will either have it load tested or buy a new one.

The usual suspects claim spikes over 14.2 while driving will tend to damage a battery. You would need to wire in a volt meter to see the spikes.....unless two wires to the nipples sounds good to you....and you can tell the difference between 14v and higher....:eek:

I would not drive the car under the described conditions as over-voltage can damage your electronic units.

And, the 3.2 alternator have a well deserved history of intermittent over charging.

pm sent.

Gerry

http://forums.pelicanparts.com/uploa...1316106877.jpg

Just swap out the VR and you will be fine. Sooner rather than later. Not a big job, so don't fret it. Order one from PP today and get er done before it kills your battery.

Taking out an alternator is not a big deal, really. Read through the procedure a couple of times, print out a copy and have it with you. Take your time, take pictures so you can remember what went where.

I had the opportunity this afternoon to put a voltmeter on my battery and this is what I found.
With the engine off a reading of 12.6
With the engine running @ 2k rpm a reading of 14.2

Right within spec according to Wayne's 101 Projects article. The battery shows absolutely no sign of leakage (looks as good as the day I installed it 18 months ago). The alternator dash light is working properly and does not exhibit any of the things mentioned in Wayne's article.

So why the dimming/brightening routine! :confused

I think I'll check the ground strap at the tranny....any other suggestions? Fan belt slipping? It doesn't feel loose...

Greer, what is the source of that page you posted?

TIA,
Jack

Let the engine run. Watch the volts closely for 10 minutes, then tell us what you see.