Electical Experts Needed: Alternator Failure??

[cbeers]

OK, the car is a 1987 Carrera 3.2L. Stock except for chip/exhaust.

Over the past several weeks, the alternator light would flicker on at start up. As soon as I drove away, it went away. This made me think maybe the belt was getting old and loose. This goes on for weeks, but only once in a while. Today, it's fine all day. I go out to the car to drive home and it turns over slow, but fires right up. Odd. Then, I go to roll up the windows (power) and they are s-l-o-w, really slow. Odd again. I think something is wrong with the motors and leave them at 1/2 way up. As I am driving home, the car starts sputtering a little. Not popping or anything, but it's noticable. I turn off the radio so I can listen more. I start to think it IS alternator related, so I turn off the fog lights and parking lights and the car immediately runs smooth again. OK, now I am worried and hoping to make it the 25 miles home. It's getting dark, but I dare not turn on the lights again. I make it home, coast up the driveway and into the garage. It is still idling fine. So, I turn on the fog lights which makes a small miss in the idle. Then, I turn on the parking lights and the car wants to die. Turn them back off, idles fine again. Turn them back on and it wants to die. So, I turn off the car for good.


So, what are your thoughts? Alternator? Voltage regulator?

I would have thought a failing alternator would be lighting up the idiot light on the dash non-stop, all the time. Fan belt is still OK since I did not run hot at all coming home.

Battery somehow? That doesn't seem right either.........




-Chris

[2.7RACER]

Chris,
I'm not an expert, but look at this thread. "Electrical Nightmare".
Wish I knew how to post it so you could click on it and go right there.

[RoninLB]

Electrical Nightmare

[cbeers]

hhhmmm....that thread seemed more about a starter issue, but still had some good things to look at. Thanks


anyone else with some insight?

-Chris

[vash]

chris, do you have a multimeter? look for that 14.something V at idle, and you should be ok.

i say you alt is going kaput. there is a fantastic alt rebuilder south of market san fran, if you need to use him.

[scottb]

Have you put a voltmeter on the alternator while the car is running? If so, is it putting out +/- 13.5 volts.

If I had to venture a guess, I'd say alternator.

[cbeers]

Have not put a tester on it yet, I barely made it home late last night. that's the next step. I found a good article in the tech section of PP.

Cliff, I think I'd like that contact, rebuilt ones here are $450-650!!

What did yours run last year?

-Chris

[scottb]

There's no magic to these alternators. I had a local foreign alternator and starter shop rebuild mine three years ago for $85, and it's still going strong.

Look in your local yellow pages, and my guess is that you'll find a local shop that can handle the work for you. A quick search on the Yahoo! yellow pages yielded this:

Hoot's Auto & Diesel Electric
Address: 501 Lakeville St # H, Petaluma, CA 94952
Phone: (707) 762-1823

It might be worth a phone call to see if they can test and rebuild yours.

Yahoo! also showed a bunch of shops near San Francisco, but they're 40+ miles from Petaluma.

Good luck!

[cbeers]

Thanks Scott, you're OK in my book

-Chris

[TCB]

My alternator died just last week. I started at the battery, cleaned all connections, +12 and ground straps. Still didn't fix anything. The voltage at 2000 rpm was still around 12 volts and the car ran like crap. The alternator was dead. Bought a bosh rebuilt and I'm good for another 22 years. Like the guys said, measure the voltage. Sounds like you are running off just the battery.
Took about 50 minutes to pull out the old one and the same to put the new one back in. I did polish up the fan while it was out.

Good Luck
Good luck

[JP911]

Chris-
It could be the voltage regulator, but I'm fairly sure that it's integrated into the alternator on the Carrera and I don't think it can easily be replaced. The only other thing to check is the main ground strap at the chassis. If it's making intermittent contact it might cause this behavior. If you need any help this weekend, let me know. I could cruise up and lend a hand.
-Jon

[vash]

riteway alternator and starter

on 8th street? south of market.

they have done two for me now, and they are both jamming. $125 , one day turn around.

[Early_S_Man]

Chris,

You need to gather hard data on how your alternator is performing at various rpms ... BEFORE you post the question to the board!

For now, a multimeter is sufficient, but for the long term ... you need a dashboard-mounted Voltmeter. The expanded-scale VDO Cockpit series is a good one I recommend. Anything below 13.2 - 13.5 Volts when engine is above 2000 rpm is unaccepable!

The gauge on the right is the one I recommend:



ps,

You can't tell whether a situation with low output Voltage is because of the regulator or alternator internals ... on the other hand, high output Voltage is ALWAYS because of the Voltage regulator!

[cbeers]

Warren, I know what you are saying, but come on now. Surely I can ask for opinions and how to go about looking into this further?

If I was so good that I could do everything on my own I probably wouldn't be posting asking for help right?

I agree on the gauge though, I have never liked having only an idiot light.....

-Chris

[rick-l]

Originally posted by cbeers
Surely I can ask for opinions and how to go about looking into this further?

I thought that is what this place was all about.

It is easier and cheaper to type and ask opinions than it is to buy the wrong stuff and replace it because you are clueless in that area.

I think what Warren meant to say is it would be more helpful if you took some measurements first.

[JP911]

I had a voltmeter in my targa and it was an easy install. It was a cheapie sunpro from Pep Girls, but it did the job and blended in nicely with the factory gauges.

[Wil Ferch]

People are funny...."The car still had 12 volts"....ahhh.... as if this were enough ?

Here's the skinny:

-fully charged battery... 12.6 volts ( measured across the battery ... car "off")

- battery at 75% charge.... 12.4 volts

- battery at 50% charge.... 12.2 volts

- battery at 25% charge ...... 12.0 volts

- battery at 11+ to 12 volts....... essentially DEAD

Wil

[cbeers]

Well, I think I found out the answer to my "Why didn't the idiot light come on and stay on" question. I almost never check out Rennlist anymore, just doesn't seem as lively as here. well, I was just over there and an alternator discussion came up and who chimed in? Our friend Loren


From Rennlist:
"Would my alternator diode circuit not at least cause the dashboard warning light to come on if the regulator fails?"

Remember, one side of the alt. light is connected to the #15 (key on battery).
The other side is connected to the regulator and plus side of the field winding.
The regulator switches (on/off) the other side of the field to ground.

If the alternator fails "on", then the field is always switched "on". Thus both
sides of the alt. light basically "see" the same voltage and remains "off". The only
real way to have the alt. light indicate an overvoltage condition is to modify
the Porsche wiring and add additional circuitry beyond just a diode.

Bottom line: A reliable monitoring system ALWAYS requires an additional and
SEPARATE circuity, i.e. in addition to the regulator itself. You really can't reliably
have a device monitor itself.

"Can you tell me exactly what is the original 3.2 90 amp alternator, where it is available and how one can prevent cooking one's battery prematurely?"

The OEM alt. is a Paris-Rhone (Valero) and can be purchased via major parts suppliers,
e.g. SSF & Worldpac, & IMC.


anyway, just thought that info would help for others wondering the same thing



-Chris