Voltage Regulator issues

[shuzboomer]

Hello everyone,

I hope someone can once again set me straight on an issue I am trying to sort out with my 81' Targa.

Since the day a purchased the car, I have been seeing the occasional flickering of the fasten-seat belts light when I drive the car. I have tested the voltage at the battery and found that its a between 13-14 volts with the engine running @ 2K rpm.

The problem had eluded me until recently that I got one of those cheap meters that plug into the cig lighter, so that you can monitor your voltage as you drive the car. Normally I get a reading between 13.x-14 volts.

The long story short, I am seeing a consistent spike on the meter every time my fasten-seat belts light goes on. The meter (probably due to quality) bounces like crazy between 14.5 - 15.5 volts.

My question is how do I tell if i have an internal or external regulator. I took a few snapshots that I will post, maybe someone can tell me what I am looking at...

There is also a wire with some frayed shielding, can someone give me a ruling on what the part is and what should I do about it?

Thanks in advance,

RBL>

[jason2guy]

the VR is that black plastic part. the little metal box w/the braided shielding is a noise suppresor, i think. first thing i would do is disconnect the suppresor and plug straight in to the VR. as far as the seat belt light- i have no idea. if uve never been into the alternator then its unclear if the car has been updated to the internal VR. thats when the VR is bolted to the back of the ALT

[wwest]

The most appropriate place to check for over voltage is in the engine compartment, near the alternator. The battery serves as a HUGE SINK for temporary or intermittent over-voltage excursions, spiking.

And the VR isn't necessarily the culprit, intermittent shorts, shorting, within the alternator stator windings can also result in over voltage spikes.

[304065]

Sounds to me like your seatbelt wire is shorting out, causing a short circuit, causing the alternator to spike in response to a high amperage (i.e. dead short) demand). Try unplugging it.

The box with the braided shielding is an EMF noise supressor. Take it out of the circuit by unplugging it , plug the cannon plug directly into the VR.

By the way your VR is an aftermarket Huco, if you need to replace it, get the solid-state Bosch

[na2ub]

Usually the newer alternators, with the internal VR have the allen key hole in the middle of the pully. Your symptoms are classic of a failing VR (and the same as mine were). The seat belt light, for one reason or another, is sensitive to voltage spikes. You would probably also see your headlights brighten up during such a spike. Replace the VR, and all will be well.

[wwest]

Originally Posted by na2ub

Usually the newer alternators, with the internal VR have the allen key hole in the middle of the pully.

Your symptoms are classic of a failing VR

Or, as I was to discover, discovered, an intermittent short of one of the alternator stator windings.

(and the same as mine were).

The seat belt light, for one reason or another, is sensitive to voltage spikes.

As is almost every electrical device inn the early 911 series, jumping tach, over-rev limiter latching up, CDI failures, etc, etc..

You would probably also see your headlights brighten up during such a spike.

Yes, but not really noticeably so.


e unless you alread, and all will be well.

Yes, the first thing to do is replace the VR, first making sure it's actually being used. But be sure to check the electrolyte level in the battery as one of the long term effects is that it gets boiled away with over-voltage periods.

After replacing the VR still keep in close eye on system voltage as the VR often isn't the problem.

[shuzboomer]

Thank you everyone who replied to my questions:

As usual, I have gotten some great info. I am eager to get home and take a good look under the lid to see if I can tell if my Alt has an alen key hole in it or not.

Based on the info that I received , I have a few follow-up questions (my apologizes in advance, if they sound too basic for all you well seasoned Porsche Maniacs out there!)

1. In order to check the voltage in the engine compartment (next to the Alt), were do you attach your test leads (pictures anyone)?

2. How can you test to confirm that your VR is not being used (upgraded to internal unit), without frying something expensive in the car?

3. It looks like I am going shopping for a new VR, a suggestion was made to replace my after-market Huco with a solid-state Bosch. Does anyone have a part # or a comment relating to this suggestion. - I have not been able to find a place that carries a Bosch VR, not to mention the last time I installed a new "Brazilian Bosch coil" it left me stranded on the side of the road.

Thanks again for all your help, I will update as soon as I get my hands dirty.



RBL>

[wwest]

Originally Posted by shuzboomer

Thank you everyone who replied to my questions:

As usual, I have gotten some great info. I am eager to get home and take a good look under the lid to see if I can tell if my Alt has an alen key hole in it or not.

Based on the info that I received , I have a few follow-up questions (my apologizes in advance, if they sound too basic for all you well seasoned Porsche Maniacs out there!)

1. In order to check the voltage in the engine compartment (next to the Alt), were do you attach your test leads (pictures anyone)?

2. How can you test to confirm that your VR is not being used (upgraded to internal unit), without frying something expensive in the car?

3. It looks like I am going shopping for a new VR, a suggestion was made to replace my after-market Huco with a solid-state Bosch. Does anyone have a part # or a comment relating to this suggestion. - I have not been able to find a place that carries a Bosch VR, not to mention the last time I installed a new "Brazilian Bosch coil" it left me stranded on the side of the road.

Thanks again for all your help, I will update as soon as I get my hands dirty.



RBL>

2.) Verify that you can see the headlights brighten as you rev up the engine and then unplug the VR and do the same test.

And now apologize for calling us maniacs....

[shuzboomer]

It is with the greatest respect and fondness that I refer to the fine folk on this forum as Maniacs. If anyone is offended, please accept my deepest apology.

RBL

[HawgRyder]

Before you spend money....clean..clean...clean..every connection associated with the charging circuit!!
I would hate to see you chase the problem for any length of time and finally find you had a bad connection.
Regulators rely on feedback to keep the voltage stable...if there is a poor connection...the feedback would drop...asking the alt to put out more power.
Pretty simple to say...but a devil of a problem to solve.
Intermittant electrical problems are the things that cause suicides...LOL
Check carefully...slowly...refer to the big old colour diagram...and by all means...have fun.
Bob

[Lorenfb]

"The long story short, I am seeing a consistent spike on the meter every time my fasten-seat belts light goes on. The meter (probably due to quality) bounces like crazy between 14.5 - 15.5 volts. "

This is a very common example of an overcharging alternator, especially for one with an
electronic voltage regulator which is more prone to cause overcharging than a mechanical
regulator. This has been a common problem for both the late 911SC ('82-'83) and the
911 3.2 ('84-'89) with their internal regulator alternators.

[shuzboomer]

Well I have been able to tinker a bit over the weekend so here is the update.

1. It looks like cleaning the contact and bypassing the noise filter did nothing to address the voltage spikes.

2. I have also concluded that my active VR is the external huco variaty and not an internal kind inside the alternator by doing the headlight test suggested by WWEST.

The plan right now is to get a replacement VR to see if it will cure my problem. I am still waiting to see if someone can point me to a model number of a "solid state" VR, the original OEM seems to be MIA from our host. The Huco is available as well as some cheap knock-offs from e-bay that I don't think I will be getting.

3. I have also noted the the alt belt may have some extra play in it, requiring some tightening.

BTW: does anyone think that it's a pain in the neck to get to the mounting screws of the VR. I don't have huge hands, but until I removed the heater hose, I could not even see the orientation of the connector on the VR. It's like the folks at the factory had children with tiny tools install the darn thing...

My 2 cents anyway. Thanks again for your comments and suggestions.

RBL

[Lorenfb]

"The Huco is available as well as some cheap knock-offs from e-bay that I don't think I will be getting."

That's about your easiest choice. That way at least you'll be able to isolate
the problem, i.e. it's very unlikely that a new regulator will cause an intermittent
overcharging immediately.

"does anyone think that it's a pain in the neck to get to the mounting screws of the VR."

Most likely the panel needs to come off if the regulator mounting doesn't use
capture nuts.

[shuzboomer]

A new VR is in the mail ( with a few odds and ends) I will comment back when complete.

Thanks again,

RBL

[shuzboomer]

Well boys and girls,

Last Sunday, I spend a few hours fiddling with the car installing the new Huco VR as well as sorting out a few other issues on the punch list.

At this time I have mixed results to report.

First, I decided to pull out the fraird noise filter and plug directly into the new VR. I have not seen any really good reason to purchase a replacement for the old part and seen a number of comments suggesting that I throw mine in a large body of water. Being environmentally conscious I desided to put it in my junk part draw until someone tells me otherwise...

Second, the new VR got installed with minimal trouble. The engine started right up with the volt meter reading 13v at idle.

I took the car for a ride around the block and no spikes where detected on the volt meter. Later, in the day however the seatbelt light did come back on for a second or two, but the volt meter showed between 14-14.5volts.

At this point, I am not sure if I am dealing with two different problems one of which seems to have been addressed by the new VR.

A suggestion was made about a possible short in the seatbelt wire, I am game to rule out that possibility if someone can direct me to how or where I can unplug the wire (preferably without using my wire cutters).

Unrelated to the issue above I discovered a rusty and crusty connection on my driverside license plate light but thats an issue for a different day to fix...

Thanks again for all the great info

Cheers!

RBL

[shuzboomer]

Cold hard failure!

The Alt is spiking back into the 15+ volt danger zone on my ride home from work.

Looks like there is going to be rebuilt Alt in my near future...

Anybody has words of advise or caution?

RBL

[pete3799]

I opted for the internally regulated Valeo sold by our host. My old alt. didn't survive the removal process so i couldn't have it rebuilt. If yours is rebuildable find a good shop and have it done.

[shuzboomer]

What alternator is really in there?[/QUOTE]

I suspect I will know when I pull it out. I expect to find the original one hand installed by some fine german gentlemen.

What's really spinning my head is that the overcharging problem seems to have gotten much worse today. I don't know if the new regulator got baked by a voltage surge or somthing. Prior to last weekend I would get a spike now and then, today I was driving 14.5-15v all the way to and from work.

At this point in time I think I am going to need to park her until I get this problem sorted. Otherwise I feel like I'm going to fry somthing else.

Anyone with a ballpark price for a good quality re-build. I think I want to stick with the external VR unless I hear different.

Thanks

RBL

[shuzboomer]

Mine has no alen slot, Plain Jane.

[Joe Bob]

Originally Posted by wwest

The most appropriate place to check for over voltage is in the engine compartment, near the alternator. The battery serves as a HUGE SINK for temporary or intermittent over-voltage excursions, spiking.

And the VR isn't necessarily the culprit, intermittent shorts, shorting, within the alternator stator windings can also result in over voltage spikes.

BTW, page 270-12 in the Bentley manual shows a digital meter testing the battery terminals for charging diagnostics.....just sayin'.....