SWB '66 911 - Hello - Charging System HELL (long)

[304093]

First of all HELLO!

I've been lurking on this board for over 10 years, and I finally decided I had to join.
Sorry to take so long, but I'm not the most fastidious "post your entire life on the internet for all to see and comment" type of guy.

I purchased my '66 911 Chassis # 304093 in 2003. It was running poorly, had the wrong plugs, the suspension bushings needed refreshing and the brakes were seized. I tackled those problems and finally had a decent running car.

The main reason for posting today is because my car now has a charging problem.

When I originally purchased the car, it had a no-name internally regulated alternator installed, with no resistor at the idiot light. Once trouble started (and I was unable to adjust the belt due to the different housing & pulley) I bought the correct fan housing, fan, and *luck* found an original Bosch alternator at Hershey in 2012 for $40!

In 2013 to get ready for Hershey, I put the whole shebang back together, hooked up the orig. 47 yr. old VR and VIOILA! Running & charging fine!
Now it's back to ORIGINAL and I CAN PROPERLY ADJUST MY FANBELT! YAY!

I finally had the engine & trans restored from 2014-16, and had the original Bosch alternator reinstalled.

Drove all summer '16 with no issues when suddenly on a nice PCA FALL tour, light came on faintly, there was no charge at the battery and my car wouldn't restart when we stopped for a break. Had to push start it.

I called the shop who did the work, they picked up car and replaced my original alternator with a NEW VALEO internally regulated alternator. Black DF wire was removed, taped to harness. Car returned to me "fixed", battery was charging fine (13.5-14.2V @ 2,000 + RPM measured across battery terminals).

HOWEVER, when I got the car back, I noticed the original external VR WAS STILL PLUGGED IN! HMM....

Thinks me: "Well, that's certainly weird but they must know what they're doing! Maybe it's a new fangled alternator that allows you to keep the external VR plugged in just for looks!"

The car drove fine for the next 2 months, when suddenly NOW, the light glows faintly and THERE'S NO CHARGING AT THE BATTERY!

On 8/24/17, I took both alternators (Original Bosch & internal Valeo) to an auto electric place AND BOTH TESTED FINE!
My original Bosch external VR tested bad or failing.
But that shouldn't matter with an internally regulated alt fitted to the car, right??

Conditions: Known good Valeo installed (External VR unplugged):

Light glows faintly at all RPM, increases brightness when I step on brake pedal.

Voltage at battery at rest, car not running: 13.2V
Voltage at battery, car running: 12.5V
Voltage at battery, car running, accessories on (lights): 12.2 - 12.5V

Battery accepts a charge fine from a Schumacher charger, returns to 13.2-13.5V static.

Voltage at terminal block on rear panel: 13.2V (where heavy 10ga black & 10ga red/white alt. wire are held by screw).

No resistor fitted to alt. light wiring (ever).

Red/White B+ wire has continuity from alt. to terminal block.

Black wire from battery to terminal block measures 13.2V, continuity fine.

Ground point near rear panel was checked, connectors cleaned and new washer and nut installed. Looks fine.

Questions:

1. What effect (if any) does leaving the external VR connected have on the system, when internal VR Valeo is fitted? Does this end up changing resistance at the light?

2. Since I have a charging problem, regardless of which alt. set up I use, doesn't this point to a wiring problem?

3. What else should I check? Is my wiring problem a bad connector at the ignition switch? At Starter?

4. If neither alternator is not turning on, what is the next step?

This has me totally confused. Appreciate any help. Thanks so much ALL!

Mitch

[Frank Beck]

Beautiful car and welcome; nice to have quiet types like you to offset the rest of us.

Voltage reg is simply an ornament; won't hurt anything to have it connected.
It does sound like high resistance somewhere. I would clean all of your connections and start with the battery. Make sure both terminals are spotless and see if either cable is warm to the touch when running. Especially important that ground strap is tight and tidy

Good luck.

[edmayo]

To add to Frank's advice, I'd run a temporary external ground source using a couple jumper cables, directly from battery ground post back to transmission housing. That will eliminate all ground problems, if that is the problem.

[davep]

The alternator light in the instruments needs to be the correct bulb specified for the application. The resistance of the bulb allows the correct current flow, during engine start, to initiate the charging process. Replacement of this bulb with an incorrect device can cause charging problems. During engine start current flows from the battery through the bulb to the alternator windings; the bulb lights up brightly. Once the engine starts, the alternator produces an opposing voltage. If the opposing voltage is equal to the battery voltage then no current flows through the bulb and the bulb is dark. If the opposing voltage is not equal to the battery voltage then some current flows through the bulb and the bulb will glow in proportion to the current. You certainly have to be careful about grounds. Ed's advice is good. Be aware that painting the fan shroud can, in some cases, prevent a good ground connection from the alternator body through to the engine & transmission cases. Also check the transmission ground strap to the body. Is there a ground wire from the alternator to the engine case?

[304093]

Thanks Frank, Ed & Dave for your kind advice. To your points:

Battery terminals are clean, cables are strong. Ground cable is recent, a generic domestic insulated one.

Both ground points in the front trunk are clean and look good.

The alt. light bulb is the original 2W type - the kind that is very hard to find locally. I guess they only exist on vintage cars now.

Yes, there is a new ground wire from the rear of the fan shroud to the case. I will check the transmission, but the last time I was under the car, there was a copper braided ground strap there.

What would cause the bulb to burn brighter when I step on the brake pedal? Could my brake light switch be bad?

I'll try the battery ground trick and report back today.

[304093]

Grounded battery to drain plug on transmission with jumper cables - no change.

Removed battery quick release - thought might be giving trouble - no change.

I'm out of ideas.

[edmayo]

Check what the voltage is on both sides of the alternator warning light check with ohm meter from instrument housing to chassis.,,,,,,and why is that spring on the trans bellcrank???

[304093]

Thanks Ed,

1. Spring on trans. bellcrank is a "helper" spring for my gas pedal. It wasn't returning 'smartly', so we installed a spring.

2. Latest findings:

Alt. warning light Ohms - from gauge housing to chassis ground = .4-.5 Ohms

Voltage at warning light (key on, engine not running):

"Pole 1" = 11.64 V

"Pole 2" = 1.37 V

Voltage at warning light (key on, engine running @ 2200 RPM):

"Pole 1" = 14.86V

"Pole 2" = 12.06

Ohms Resistance of bulb holder across poles = 9.5 Ohms (sounds high, could this be the source of the problem??)

I should add, I'm not sure if the pole reading 14.86 was the same as the one that read 11.64, it was hard to get my hands in there and see.

I noticed on the bulb holder itself, one spade terminal is marked "14 +", while the other is not marked at all.
It's a bulb, does it matter which wire is hooked to which post?

[edmayo]

As you may know, the alt. light works on opposing voltage principle, if the voltage is equal in both directions it cancels so there is no flow and the light goes out. You have much different voltages when the engine is running, so the light never goes out. The red wire is from the battery and should read bat. voltage, the blue wire goes to the term.+61 of the alternator and should also read almost equal to battery voltage, thus turning out the light. If that 12.06 at pole two is the blue wire then there isn't enough voltage coming from the alternator. Frankly I'm not a fan of internal regulator systems, they go against all electrical wisdom of keeping electrical components away from heat. Those systems were very troublesome when they came out in 83. I would reccommend going back to your original external reg. Bosch system, they only lasted 30 years or so!


And when you get all this figured out you really should fix your throttle linkage, if you have to add a spring there is a big problem that really needs to be corrected. BUT ONE thing at a time.

[304093]

Thanks Ed.
What about the Ohms resistance on the bulb holder? 9.5 Ohms - Isn't that too high?

Isn't the 14.86V at Pole 1 on the holder coming from the alternator?

There are no red wires at the bulb holder, only 1 blue and 1 blue/green wire.

I had the alternator checked, and the shop guy says it's OK. I think this is a wiring problem, where there is a voltage drop that is somehow interfering with the charging circuit.

I switched the brake light wire (black/yellow) to a different keyed hot fuse, and that actually made the bulb much dimmer. It no longer gets brighter when I step on the brake pedal. So I think I'm making some progress. I also removed, cleaned bulbs, etc. and replaced ground connectors in both taillights.

I get what you're saying about the internal vs. external regulator. I've read many of the posts, especially by John Cramer, that talk about this. However, I have had the charging problem with both setups.

What else can I check?