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Join Date: Mar 2004
Location: Piedmont (OKC), Oklahoma
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Question Voltage regulator replacement

I just purchased an external VR for my 1980 Weissach 911. When I went to put it in I found that the original VR was there, but the wires were taped off. Presumably someone must have replaced the original alternator with a newer one that has the built in VR. Before I order another part what should I be looking for and are there other concerns that I need to keep in mind?

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1999 VW New Beetle
1985 VW Vanagon Westfalia
1983 944 - Parting out
1980 911 - Weissach Edition
Old 06-24-2004, 10:54 AM
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First of all, why do you need to replace VR ??
Any problem with your charging system ???
As long as your batt. is charging ??? where is the rush ???
Truly, Phil.
Old 06-24-2004, 05:26 PM
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I had the same thing happen to me. Turned out my alternator had been upgraded and had a built in regulator. If I recall correctly, I believe I erroniously installed an external regulator causing the alternator light to remain on. I think as long as your alternator light is behaving properly your probably OK. But just to be sure you can take out your alternator and check it to see if it has a built in. Maybe someone else has an easier way to check. I guess one thing to do is check the voltage on your battery to see if that is normal, and not overcharging. Bottom line is you don't want battery to overcharge and explode.
Old 06-24-2004, 09:51 PM
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Here's the symptoms. When I'm driving I get bright lights for a while then randomly dim, then when sitting parked if I rev the engine I can see a noticable increase in the brightness of the lights. (This affects all of the lights - interior and exterior) With the stereo on with bright lights the amp drops out, with dim lights it works fine. With or without the stereo on I still get the random dimming of the lights. It is random and I haven't been able to directly tie it to an accessory or anything else. In addition it doesn't corespond to bumps in the road or anything like a loose wire might. It happens day or night.
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Old 06-25-2004, 09:08 AM
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A healthy alternator should be giving constant power output, so unless someone else has any better ideas you may want to pull the alternator and have it tested. I took mine out and took it down to a place called Rotex here in LA. They bench tested it and gave me a really cool computer printout with charts giving me peak power output values, some curves on RPM/wattage and a clean bill of health for my alternator. Cost me nothing. The only trick is getting that thing out. It requires a degree of manual dexterity. Oh, and make sure you keep track of how it's wired up.
Old 06-25-2004, 09:36 AM
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I've recently had some electrical issues and I installed a volt guage in my center console to keep track of the alternator. A quick and easy test of the health of your alternator would be to connect a voltmeter to your battery while the car is running (idling). If the meter reads below approx 13 or above 14.5, you probably have a problem with your alternator.
Old 06-25-2004, 09:42 AM
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I would also monitor the battery voltage. You can use the cigarette lighter jack to read the voltage. If you have a voltmeter you can purchase the adapter to connect between the lighter jack and the meter. Now you can monitor the voltage while driving to verify if it is changing and by how much. I personally don't like the idea of the internal regulator. It is easier to just replace the external V/R when you have a problem. Pulling the alternator to change the V/R is just a pain in the keester.
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Old 06-25-2004, 10:09 AM
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TallyRich:

It's pretty common to see the external regulator replaced with an internal one, particularly on the Paris-Rhones.

First things first: check the archives under my name, early_s_man, and lorenfb, there are a ton of alternator threads that describe everything about the system so you know how it works.

Second, check the belt to be sure it's not slipping. You want about 1/4" of deflection when you push on the side of the belt with your fingers (engine OFF!). Any more than that the belt could be slipping at high rpms causing the voltage to fluctuate.

If you install a voltmeter, try to keep the leads as short as possible and run them directly to the battery: you want to measure the voltage AT the battery, not elsewhere in the car. Remember that every connection comes with a small voltage drop.

So pulling the alternator is really no big deal, once you've done it a few times you can get it out in about 20 minutes. The archives have detailed information on what connection goes where.

At the end of the day it doesn't sound like a mechanical problem with the wiring, but clean everything anyway. Oxidation makes the circuit do strange things. I'm going to be replacing my carrera alternator with an externally regulated one this summer, it's a good idea to have the VR away from sources of engine heat.

My theory is that when alternator manufacturers started making the VR integral with the alternator in the '80's (1982 first year for Porsche 911) it was due to their experience with cars that had the alternator mounted well away from the engine (BMW 320i, for example), not 3" from the block. All that engine heat in the Porsche isn't good for the VR, and occasionally causes it to shut down, a huge PITA. I plan to go back to the external VR, if it was good enough for the 962, good enough for me!
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Old 06-25-2004, 10:20 AM
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This is really helpful. Thanks. So is there a way to change back to an external VR without replacing the alternator? I agree that it should be external. Are these alternators worth rebuilding or if it tests bad should I just replace it?
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1980 911 - Weissach Edition
Old 06-25-2004, 10:42 AM
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No, the internal regulator is integral with the brush holder, so you have to get a brush holder with a "DF" male faston terminal on it and connect the black wire from the External VR to it.

Whether it's worth rebuilding depends on the type of alternator and your electrical load. If it's a Paris-Rhone, junk it. If it's a Bosch or a Motorola-Marchal, rebuild it. If you have a lot of electrical loads you may want to consider an internally regulated, uprated alternator with greater power capacity, but these require changing the fan shroud. '

Good luck!
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Old 06-25-2004, 10:46 AM
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Replaced the VR and the car ran fine for 3 days then died. (Battery not charging) I called the vendor, they sent me a new VR and I now have that in. I started the car with a high amp charger and then immediately removed the charger. Let the car run for 30 minutes or so with the lights on and the stereo up (amp blasting). At the end of that time the battery still had enough umph to start the car. So, it sounds like it's all happy.
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1980 911 - Weissach Edition
Old 07-26-2004, 09:33 PM
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fwiw.
I found a new[for me] rebuilder.. He does mostly big rigs and marine alternators and starters.. my friend had his alt's out-put increased for his boat.. so WTF I go there and find two older brothers running the shop and they take notice of the porsche alt introduction because one of them was a P owner awhile ago and he wants to bs about P. "so a compliant is that the internal regulators toast because of alt placement". "What are you talking about" blah, blah, blah. "So do you think 210deg is a prob with internal regulators?" "NO" "How about 220 deg or 230deg?" After a few seconds of thought, "Maybe." "Can you increase the out-put of my alt if needed?" "No. Not enough room to add windings." What kind of bearings do you use?" " Jap ones. The Good ones."

"How about the starter sol seizing due to the engine heat?" "Well it's super tight clearance of the plunger and case to begin with so I guess heat could tighten the clearance." "So if that is what's happening how do I fix it?" "I could mill out the case a little bit." "How much, maybe a .001 or .002?" "Yeah, that should do it." "How can I full field an internal reg?" "It can be done but it's very involved for me to do that kind of custom work." "Do you do mail order if someone asks?" "Maybe if it was sent properly and I could use the same packing for the return."

So my three 980w Valeo alt's all put out over 90amps with no AC ripple.

This shop is a home run.

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Old 07-26-2004, 10:29 PM
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