So I’m about 30 miles from home the other night. I go to start my car up and the red alternator light doesn’t go out. I checked to make sure the belt was tight and jiggled the voltage regulator and the alternator harness plug but the light stayed lit. So I drove home and made it. The bulb stayed lit and didn’t vary in terms of brightness. I did notice my volt meter was not at its usual ~14 volts. By the time I got home, it was between 10-11 volts.

I suspect my problem lies with one of the following: the VR, the alternator, the connections or the wiring. I’ve already inspected the connections at the relay board and tried another VR of unknown condition, but no change. I had inspected the alternator harness this spring prior to installing the engine. The battery is new. All the grounds are tight. The alternator appears to be firmly in place. I haven't tried yet to put a wrench on the lower bolt yet.

My VR is of the newer variety so I’m not sure how to test it.

I would like to rule in or out the alternator before removing it from the car. I hear that job sort of sucks. I’m going to test the battery voltage with the engine at a fast idle, but I suspect it will read way below 12 volts. I am also going to remove the VR and jumper the D+ and DF terminals and test the battery voltage at a fast idle. This should simulate the VR asking for maximum output from the alternator. Assuming this shows the same voltage (<12 volts), should I just remove the alternator at this point?

Advance Auto Parts has rebuilt Bosch alternators for $129 delivered to their store. They also claim to be able to test my alternator. Is there a better brand out there?

A Genuine Bosch Remanufactured alternator is your best bet. Be SURE it comes in a Bosch box, not a "white box". Don't let them tell you the quality's the same, 'cause it's NOT. There is a known issue with the positive stud on the back hitting the rear cover, so match the length carefully and shorten it if necessary.

The Cap'n

.... only go with Bosch rebuilt by them - same for starters or anything else for our 914s that you can't get new - or for a reasonable price anyway.

Also stick with the Bosch VR spec'd for your model/MY 914 at the PET. They're still available & not too expensive from AA, Pelican, PP/A, SMC, etc.

Changing out the alt. is easier than it is made out to be,, no fear. Bosch.

The front tin was designed to be sectioned off. Once you get the belt loose and the wire unplugged, you have maybe 30 minutes of cussing under the car before the alternator comes out. Putting it in again is easier, as you know how it needs to go. Its even easier for us as we have headers, so all the heater crap is out of the way. I'd rather pull the alternator then have to replace a throttle cable or clutch cable to the pedal cluster.

Zach

With a meter on the battery and the engine at a fast idle, the volts stayed at about 12 volts with no other power accessories on. I removed the VR and jumped the D+ and DF terminals and the same result.

Advance Auto Parts claims its a genuine rebuilt Bosch alternator. We'll see.

I've been running a 75 amp unit from Eagle Auto Electric http://cgi.ebay.com/ebaymotors/VW-Mini-Bus...sQ5fAccessories for over two years. They are rebuilt 55 amp ($74) and 75 amp ($94) units for our 914's. I have had no issues to date .

Does the 75 amp alternator require a different cooling boot?

About 13.5 V is more like it.

...who says it's the alternator or voltage regulator????
get it tested ...before you start burning(tearing) down the house!

P.S. always look for green and clean!!

No, It is a direct swap out. BTW, when I re-installed my engine this month I previously and this time again grounded my external oil cooler fan where the tranny ground strap attaches to the chassis. I made the mistake of inserting the fan ground wire first (closest to the chassis)and then the tranny ground strap on top of it. When I started my car for the first time the alt light came on and stayed on although dim. I reversed the two connections and the problem was solved. Make sure your car is well grounded. I used a lttle rust remover and a wire brush to clean all the ground contact points.....it helps.

Good point. Grounding is a black art, especially when it comes to high frequency stuff.

That's kinda harsh. I suspect it's the alternator based on the data I have gathered.

Correct me if I'm wrong, but don't I have to remove the alternator in order to have it tested? If not, what specifically would you suggest I do?

P.S. What does "always look for green and clean!!" mean???

Just a WAG but measure the resistance from the alt case to engine ground if its
not 0 OHMS you may need a ground strap from the ALT to engine case or measure
the voltage from the engine case to the ALT case should be 0 volts if its more then
you need a ground strap.

...sorry you took that so harsh?....but the repetition in grievances gets to be a little irritating...when most questions members ask could be answered by doing
searches either here or on other boards......I believe the man above answered
the 1st question you asked.....as for the 2nd question "green" is an auto repair term for "corrosion" usually comes in that form among other colors(black) also.
hope you get everything under control........later

You know, at idle, i am getting 13.5 volts, and yet, the alt. light is on. WTF???

Check your fuses. See if they are all good and have a good contact. Did you knock one out? There is a fuse, if knocked out, bad connection, or blown that will cause the alt. light to stay on......my $.02

I'd figure I'd post a quick conclusion to my issue for future searches of this topic.

I put the new alternator in and it solved the problem.

Taking the alternator out was not difficult. I have 2.0 SSI HEs so I think I probably have better access than those using stock HEs (esp '75-'76).

I had to remove the warm air guide, the 3 way branch piece, and the j-pipe that goes up through the tin. I also disconnected the pipe that connects the HE to the air valve. I only disconnected it at the HE and then pulled it out of the way with a couple of bungy cords, keeping the heater cable and flexible hose in place. The front driver's corner of the tin comes out with 4 screws (now I know why that wasn't one piece).

Installation was a little more difficult, but not too bad. Getting the plastic sealing ring to fit properly between the alternator and the tin proved a little challenging. Once I had the lower bolt in place, I used a bungy cord from the pulley to pull upward to reduce the mass of the alternator.

...without testing, not a bad guess?...I don't know whether to say bad or good
for you?...depends on what it cost & how many knuckles you skinned....but
I'm glad you fixed your problem

Occam's Razor ;-)

Okay!