Alternator - Voltage Regulator, WTF Options

[r_towle]

Even I remember slits runs a six cylinder....and I don't always pay attention.

[damesandhotrods]

Pelican Parts - Product Info


Electricity good…

[Elliot Cannon]

Seriously, tap the VR a few times, it may be stuck.

My six conversion is acting up with alt/reg issues. Has operated with no issues showing close to 14 volts on the gauge under power. Mine is a 2.2 carbed car with webers, MSD, internally regulated alternator and standard point ignition. A few days ago the gauge started reading 12 volts. I put a meter on the battery while its at idle and it says 11.85 volts. I share your pain as I have always been challenged by figuring out electrical problems....Maybe some of The 914World house experts can chime in and help us out...

Mine (2.7L) doesn't show correct charge until 2K (approximate) RPM on startup. I have to blip the throttle to get the light to go out.

The diode or diodes in the alternator could be bad. The alternator makes AC voltage and is then rectified to DC.

The brushes could have gone south (worn out).

Pull the alt and have it tested.

Slits, if you have upgraded to an internally regulated alternator, they recommend a 91 ohm resistor added to the alternator light. My light drops out at about 1k rpm.

Keith

I don't use the internal VR. There was a problem when the engine got hot and being the VR is close to the case, the light would come on from an overheated VR and give the driver a heart attack as he would think he lost his cooling due to a broken belt.

Maybe it's a poor excuse but I am known for those.

You're known for poor excuses or heart attacks?? (IMG:style_emoticons/default/happy11.gif) (IMG:style_emoticons/default/poke.gif)

[AE354803]

The solid state hella unit from Pelican Parts is going to be way more reliable than the old bosch electromechanical relay VRs, unless you are doing concourse go to the new solid state VRs.

Also, they can't (won't) test the alternators at oreilly or autozone, maybe if you know someone with a machine then you can wire up the VR control circuit, otherwise you have to diagnose in the car.

I'd just replace the VR with the Hella unit and if that doesn't fix it at least you have a reliable VR.

I fixed my charging issue (seemed like a bad alternator) and saved myself a lot of hassle just by putting in the Hella VR.

[Mblizzard]

Ok so here is the question. I have possibly two voltage regulators that are good assuming the alternator is bad. So does it make sense to buy a third for $30 when a rebuilt alternator can be had for slightly more than $100? They possibility of two bad regulators seems smaller than a bad alternator.

Going out to do as the captain suggested and check and check all fuses and connections.

[r_towle]

Is there an alternator test stand locally?
We have a great rebuilder here, hopefully you do also.

I prefer to have the local shop rebuild my old units versus buying an imported rebuilt unit that have had a very poor history or reliability.

If you do end up buying a new or rebuilt unit, save the receipt, you may need it, within one year.

Rich

[ThePaintedMan]

914s are not known for losing cooling function when the alternator belt breaks .....

The Cap'n

(IMG:style_emoticons/default/confused24.gif)

George- The fan is affixed to the crank. It spins when the engine turns over. Not like a 911.

Haha, I know, I was, in a way, agreeing with Capt. But then SLITS corrected us both with the /6 information. Of course on a /6 that would be not be a good thing.

I had to explain all of this to my fiancee once I got the car. I always told her if she ever saw her alternator light go on in her Blazer to STOP immediately (serpentine belt). But when I got the 914 and had to drive home with the alternator light on (bad VR), she called me a hypocrite and told me "Remember, you're supposed to stop immediately dummy!"

[Mblizzard]

Ok so maybe I will get that kick inthe groin anyway! I have come to the conclusion that it is the alternator. So I am going to replace it and then see about the voltage regulator.

I have done the alternator swap with the engine in and taken it out to do the swap. Best I remember it is about even on the amount of work for each method. Of course I drink a lot so my memory is not what it use to be. Any thoughts on the least painful method?

[r_towle]

its faster to leave the engine in the car.
Alternator swap is about 30 minutes.

Remove heater stuff....leave HE alone.
Remove belt
Remove upper bolt on alternator adjuster...dont lose
Remove lower nut and bend it out while pulling therubber boot off the backside.

Go up top
Unplug it
fish wire and grommet down the hole
Pull bolt out of the alternator and remove tin and gasket

Go below again.
Pull the alternator out, down and twist it...it does fit.

Remember, just remove all the heater things...then its quick.

Rich

[Tom]

In post #15, you mentioned that the car died when the cable was removed. Not good for alternators! (IMG:style_emoticons/default/sad.gif)
Tom

[worn]

Ok seems simple. Voltage light on dash on. Battery dies. Replaced voltage regulator with a wells VR650. Light on dash off. All seems good. But voltmeter shows the voltage dropping the longer the car runs until it dies. Voltage does not change regardless of engine speed.

Put the old regulator back on. Light on dash stays on regardless of engine speed. But voltmeter shows an increase in voltage with engine speed. I have not gotten the battery charged yet to see if running the engine discharges the battery.

I am at a loss as to what try next.

I found this article very useful from the Bird site. The diagnostics section allows you to make a few jumps at the VR to at least find out if your alternator is capable of power.

http://www.pelicanparts.com/techarticles/9...roubleshoot.htm

I have replaced alternator, VR, wiring harness and the light still needs a 2 k blip to go off. But it does charge. A voltage gauge is a handy thing that almost all cars no longer have. I actually suspect the battery is going.

I expect the reason Slits sees the same thing is that the fan is somehow stuck to the alternator pulley (IMG:style_emoticons/default/laugh.gif) .

[Mblizzard]

In post #15, you mentioned that the car died when the cable was removed. Not good for alternators! (IMG:style_emoticons/default/sad.gif)
Tom

Tom I am no expert and I may have this all wrong but for my car which lacks FI, it should have no impact on the electrical system or the alternator. The voltage regulator is between the alternator and the cars electrical systems so there is no posibility of a surge. So I was taught that until the age of computer controlled systems, that the alternator does not really care what is happening with the rest of the car. It spits out power as demanded and in relation to engine speed. Just to be clear, I stated my understanding and ask the following question because I want to learn, not to be a smart ass in anyway. I have learned so much since finding this forum that I just have to keep asking questions. Ok so what am I missing? Is it something specific to all alternators or just the 914 system?

[SLITS]

In post #15, you mentioned that the car died when the cable was removed. Not good for alternators! (IMG:style_emoticons/default/sad.gif)
Tom

Tom I am no expert and I may have this all wrong but for my car which lacks FI, it should have no impact on the electrical system or the alternator. The voltage regulator is between the alternator and the cars electrical systems so there is no posibility of a surge. So I was taught that until the age of computer controlled systems, that the alternator does not really care what is happening with the rest of the car. It spits out power as demanded and in relation to engine speed. Just to be clear, I stated my understanding and ask the following question because I want to learn, not to be a smart ass in anyway. I have learned so much since finding this forum that I just have to keep asking questions. Ok so what am I missing? Is it something specific to all alternators or just the 914 system?

I was always taught and read that if you disconnect the battery on an alternator system and run the car, it will fry the alternator. Now, if it was running while the bat lead was disconnected I would assume the same thing would happen.

[Steve Snyder]

I was always taught and read that if you disconnect the battery on an alternator system and run the car, it will fry the alternator. Now, if it was running while the bat lead was disconnected I would assume the same thing would happen.

The section on alternator diagnostics in the 914 factory service manual set states about thirty times that disconnecting the battery when the car is running will fry the alternator. The Porsche engineers seemed to be pretty darned sure that it is a bad thing to do.

[damesandhotrods]

When I went for my mechanics license, the word was never run an alternator without a load. But disconnecting the battery for a few seconds for to see if the alternator was working was an accepted trouble shooting practice.

[Tom]

Mblizzard,
I also am not an expert, however, my understanding of alternators and voltage regulators are as follows; the voltage regulator regulates the current applied to charge the battery depending on a reference voltage from the battery, less battery voltage = more charging current. If the reference voltage is suddenly removed, (equals 0 volts), the the alternator tries to put out max current all at once. The diodes that change the AC voltage of the alternator to DC voltage for charging the battery are rated at certain voltages. In case of a sudden spike exceeding the diodes working max voltages, they can fail either in the open condition or shorted condition, either case will cause the alternator to be inoperative until repaired.
I remember in the days of generators back in the 50's that what you did was an acceptable way to check if the charging circuit was bad or the battery was bad. Not so for the new, ( after 50's) alternator equiped cars. Call up a mechanic that you trust and ask what they think. Most of the owners manuals nowadays have something in them about disconnecting the battery when running to protect the computer systems yes, but that voltage spike would destroy not only the computer, but the alternator also.
I hope this either helps you understand the alternator/regulator system in our cars or promps you to seek additional knowledge to improve your understanding. As I said , I am not an expert, just repeating what I have been told for many years.
You mentioned a center console change, maybe the previous owner has done some wiring changes that you are unaware of that could be giving you some problems.
Tom

[Mblizzard]

Tom thanks for the response. I really appreciate the time you took to write that. It sounds pretty expert to me! The thing that I was told was that because in most cars the batteries are wired in parallel to the electrical system, not in series, then the reference voltage never truly goes to 0. Once the battery has energized the magnets in the alternator and it is spinning there is voltage in the system and the voltage regulator just controls where it goes. While it is correct that removing the cable can dramatically change the voltage, I was taught that unless the battery is wired in series, the drastic voltage change while possible, is less likely to occur and damage the diodes.


The wiring in this car is a nightmare! I think I sorted the center console pretty well as
everything works. Now I am trying to get the gas gauge to work. Was looking at the wires and it should have a black, green, and a brown at the fuel sending unit. Nope it has a green and two blacks? I need a drink!

I think that I will revise my approach in the future to limit the removal of the cable.

[Mblizzard]

Well went ahead and ordered new alternator. Did a final check of the wires tightened up all connections light still came on. Fine I resigned myself to doing the swap. Charged the battery to do a drive to test the newley installed jets. No generator light. Jamming out 13+ volts ran all day no problems?

This car is toying with me I know it! I guess I will keep the alternator on the work bench so the car can see it in order to have that intimidation factor!

[worn]

In post #15, you mentioned that the car died when the cable was removed. Not good for alternators! (IMG:style_emoticons/default/sad.gif)
Tom

Tom I am no expert and I may have this all wrong but for my car which lacks FI, it should have no impact on the electrical system or the alternator. The voltage regulator is between the alternator and the cars electrical systems so there is no posibility of a surge. So I was taught that until the age of computer controlled systems, that the alternator does not really care what is happening with the rest of the car. It spits out power as demanded and in relation to engine speed. Just to be clear, I stated my understanding and ask the following question because I want to learn, not to be a smart ass in anyway. I have learned so much since finding this forum that I just have to keep asking questions. Ok so what am I missing? Is it something specific to all alternators or just the 914 system?

The manuals all say not to do it, but now I too wonder why. The battery serves as a sink for excess voltage. I think the regulator uses a zener diode as a reference, but not absolutely sure away from some diagrams. Some alternators are battery referenced and some are self referencing. I am assuming that there is some possibility of a vicious cycle starting but not sure what it would be.

[r_towle]

Well went ahead and ordered new alternator. Did a final check of the wires tightened up all connections light still came on. Fine I resigned myself to doing the swap. Charged the battery to do a drive to test the newley installed jets. No generator light. Jamming out 13+ volts ran all day no problems?

This car is toying with me I know it! I guess I will keep the alternator on the work bench so the car can see it in order to have that intimidation factor!

Go have someone do a load test on the battery.
You may have a flaky cell that is causing this.

rich