zakk

About a week ago I had my battery completely drain while driving, I figured the alternator died. I got the car home via multiple jump starts (and a unlatched hood at speed incident!). I figured I'd check the simple stuff before I went and
removed the alternator. Well, the belt tension strut on the AC Compressor was broken; it was broken in such a way that there was still some tension on the belt, but I figured that was a likely cause.

So this weekend I replace both the belt and that strut, tighten everything up
and jump start the car again. After leaving it idling for a bit, the gauge is still
reading 12 volts, and I'm reading around 11.96 volts at the battery posts.

So, did my alternator eat itself and the broken strut was just there to confuse me, or should I try this with a fresh battery?

Dlefko

check your grounds.

that's all i got

SidViscous

Replace the regulator

IceShark

Sid, is actually correct in the end since you have a voltage regulator that limits output to about 14.0 to 14.1 volts. That is too low. You want one that is at least 14.4 volts.

I sell the adjustable voltage regulators for $21 with the shipping if you want one.

Having the broken strut only made matters worse for the alternator output. I really doubt you hurt it in any way, though.

You have two problems facing you. Once you replace the turnbuckle strut you either need to drive at freeway speed for about 8 hours straight to get the battery charged up with your stock voltage regulator or just put the battery on a charger for a day.

Then see if the battery will get up and stay up. If it can't then you probably sulfated the plates. You can try and recover that through some charging schemes that sometimes work but better resign yourself to maybe getting a new battery sometime in the near future.

zakk

So is the regulator definitely toast in my car if I'm seeing 12v at the battery, or am I seeing symptoms of a really weak battery?

Note that the same day the car died on me the gauge in the car started out reading around 13 volts that morning, and as the day progressed it slowly dipped to 12, and then kept dropping until it died about 2 miles from home (if only there wasn't so much traffic!) Probably a total of about 1.5 hours driving.

Unfortunately I have no idea how long before this the tension strut broke.

led

I say it's the reg if you get ~12v at the battery. AFAIK, the battery is only used to start the car, after it's running, the alternator is responsible for power supply. You should be getting more than 12v at the battery in order to charge it properly and around 12v with the car off.

DanD

What IceShark said...

The original problem was the broken adjuster. But any time the battery is challenged for extended period of time, it can become damaged (shorted). Charge it up good and see if it will hold a charge.

I suspect you'll find a bad battery.

DanD

IceShark

I suspect the alternator belt was slipping pretty bad, you know the alt will draw one HP pretty easy. That is a lot of stress on a loose belt and surely wrecked the belt. Replace the adjuster and belt. As long as you are in there, get a good adjustable voltage regulator to replace the original.

zakk

Yeah, I replaced the belt with a new one. The old one wasn't all that great looking. I was hoping to avoid replacing the regulator since I have a 951 and alternator access appears impossible without removal. Maybe I'll just suck it up and use it as an opportunity to get the grounds+positive cables installed too.

IceShark

zakk, I have sold 100's of these adjustable voltage regulators, I move more of this SKU than anyone in North America. Sort of surprised me when I heard this from the manufacturer.

Anyway, I know of no one with a 951 with the motor in the car and turbo in place that has been able to change the regulator out. NO ONE! My customer base has the best and brightest, so resign yourself to pulling the alt.

As far as battery cables, you should probably do that. But it will take a week or two for the negatives as I had a run on them and sold out. I hope Molex will get me the new parts quick but this all happened over the weekend and I just ordered parts this morning.

A lot of pre-85.5 owners want to upgrade the negative once they hear from a friend how much better it makes the electrics and life.

zakk

Already have a set of the grounds and a positive cable sitting here waiting to be installed. I never did the ground because that coolant hose is very much in the way on my car, but now that I have to drain the coolant for the alternator anyways....
I'll PM you after I get some work done about a voltage regulator. Might as well while I'm in there.