I have a similar issue so I'm going to bump this thread.

I pulled my generator out and I can spin it with my electric drill, I've got a multimeter "+" lead on the big lug and "-" to the frame. Shouldn't I be seeing 12-14 volts?

I'm seeing less than a volt.

I think there is suppose to be a voltage regulator under the back plastic cover. Any body know how to tell if the problem is the regulator or the generator?

 

Are you being serious? You can't test an alternator like that! The alternator must be driven by the engine and load tested with a fully charged battery. You cannot do this with a drill!

You should see 13.5-14.0V at idle with a fully charged battery. Loaded with 100A, you shouldn't see the multimeter drop below 12V at about 3000 RPM. It should then rebound quickly when the load is removed.

With these alternators, you also cannot replace the regulator alone. They are regulated via the exciter wire from the ECM and cannot be serviced like the old-school generators. Replace it or you'll have to find a shop that specializes in rebuilding alternators. It's usually not worth it compared to the price of a reman'd piece.

 

Sadly, yea, I was serious. I guess there's some gaps in my electrical theory education.

Everything is good now though. I found a local shop that rebuilt it for me.

Le's Auto Electric, 640 W Town St., Columbus 43215 (614) 461-6933. Highly recommended! One of the other shops I called looking for a rebuild/repair gave me his name and number.

Great service, great price. Dropped it off at lunch time on Thursday, picked it up lunch time Friday. Small owner/operator shop, been around for a decade or more. Low overhead... the shop is a converted gas station, no TV, no WiFi, no website. Not a native English speaker, so communications took some extra effort, but well worth. He does starters too.

I was going to go with a rebuilt unit from Maniac Electric Motors in Dallas TX. Great prices, shipping included for both the re-build and core return. And they've got a website with some nice technical info. They also have an Ebay store with an excellent feedback rating. But I was able to get the same price locally, and I didn't have to deal with the core charge and return.

Its installed and passing the Ross-Tech VagCom test.

A4 B5 1.8TQT AEB

 

Ok, first, is this alternator changing season? I did a search and a few popped up.

My wife's car is a 2001 A4 1.8TQ with 201k miles. Battery is about 2 years old. Battery light started going on/off this past week. My PREGNANT wife tells me today that the light was on permanently while she was 55 miles away at work. Battery voltmeter registers at 12V. She drives on and shuts off all unnecessary electrical equipment (radio, heat/AC, heated seats, etc)! She tells me to be ready to "rescue" her when she calls again. I'm like "ok". She calls me 2 miles away saying that the battery is now down to 8 volts! I say, "when you better not stop since the car will not restart". She turns off the Xenon lights and puts the parking lights on...she BARELY makes it home. She pulls it into the garage. As I get in to check out the car and try to rev the engine...it won't even rev!!! She LITERALLY just made it home! What luck! So anyway, the battery is on a charger now and I am in the process of researching potentially changing the alternator.

2 questions:
1) When you say they "rebuilt" it, what did they actually rebuild? I see from Autozone that I can get a reman Bosch 90 amp alternator for $160 (after I give back my core).
2) To remove the fan, I saw this:

http://forums.audiworld.com/a4/msgs/2847677.phtml

To remove the fan, do I need some form of HEX key wrench?

 

1. A rebuilt alternator usually means the bearings, rectifier, voltage regulator, brushes, and whatever else is deemed worn-out or in need of replacement during remanufacturing. Can you rebuild it by yourself? Yes. Is it worth it? By the time you figure out the exact problem and source all the needed parts, no. Many companies offer quality remanufactured alternators with a warranty.

2. To remove the fan, usually the 2 or 4 small bolts on the front of the fan are removed and the fan itself is removed from the pulley. Unfortunately, unless the front end is in "service position" and the radiator is pulled forward, that is nearly impossible to do. To remove the entire pulley, you will need an 8mm hex (IIRC). Usually, that baby is loctite'd and very tough to loosen up. You'll need a socket attachment for the pan-bolt and a very strong pin to hold the pulley in place.

If you absolutely cannot get that bolt loose without stripping the pan-head (I've run into this), remove the front bumper and put the radiator in service position. You can remove the bolts from the front of the fan pulley if you need the extra clearance.

Additionally, it might be best to replace your battery at this time. If the car pulled that hard on the battery alone for that long, it might be toast.

And last, that brief write up doesn't mention the most important thing about replacing the alternator: DISCONNECT the BATTERY first!!!

Good luck!

 

Eh, no worries. We all have questions. It's how we learn.

 

I was able to change out my alternator without "assuming the position" (service).

Like the link to audiworld says, I removed my fan pulley bolt from the back. I removed the hose to the intake, and in my case the throttle vacuum actuator deal (not sure of official VAG term).

My fan screws come from the engine side, so removing the fan from the clutch was not an option. (I first thought I could skip removing the fan, until generator mounting bolt made contact with the fan clutch as I unscrewed the mounting bolt.)

First remove the belt. A 17mm open end fits the top facing lug used to flex the tensioner on mine, but I know some have a lug the faces front.

The hex head socket bolt that holds on my fan is 8mm. There is a support from the intake manifold to the engine on mine that, combined with how close the bolt is to the side of the engine, makes access tough to get a hex socket and ratchet in there. You can use an "L" hex key, its just tedious at 1/6th turn at at time. A T50 torx head will fit to spin it the rest of the way out, if it is already loose.

You need to lock up the pulley by putting a much smaller hex key or similar item in one of the holes in the face of the pulley. It needs to be inserted from the back, at about the "2 o'clock" position. You can't really see the pulley hole line up, so you're doing it blindly, which makes it a pain. I put a flashlight behind it to help me line up the hole.

I know which hex key fits to lock it up because it already has a bend in it from using it in the same manner during my timing belt project. The point is that I can't tell you what size hex key, but it is smaller than you think it would be, and it is small enough that it will probably bend it. (on my pulley anyway.)

Remove the two wires on the back of the generator, take out the two mounting bolts and it slips out pretty easily. You may have to tap it with a mallet or something soft to get it loose.

 

Ok, Autozone screwed me. Actually it was just the stupid person that answered the phone. I called them for the part, they said they needed to order it and I had to prepay. I say, "No problem, but the car's alternator is dead." They say, "Just don't shut the car off when you get here." Since the store is only 2 miles or so and I had a fully charged battery, I say, "Why not?". So I run down there, not even stepping on the brakes, but using the handbrake to stop/slow down (i.e. - stepping on the brakes uses battery juice). I get there run up to the counter and say, "I'm the guy with the Audi". So they go the computer, type up the stuff and say, "Oh... it's out of stock..." I was so freakin pissed I started screaming at the guy. "You couldn't f$#ing tell me this on the phone and had me drive over here when it's 9F outside with a bad car?" So anyway, I gave them hell.

So I run to my trusty mechanic who was able to source an alternator, but about $20 more. No problem. After 2 days of waiting, we get the part. It was the wrong part! He ordered another one which got rushed over and that was also wrong! We finally get one that looked exactly the same with one big difference...

They pulley that came with it didn't have the "clutch", it was a bit larger in diameter AND it had 1 more rib than the stock unit! We tried to see if it would fit anyway and it did. We used the "outer" set of ribs and left one rib open in between the belt and the alternator. The belt was long enough to accommodate the larger diameter pulley...

So my question is, since this pulley doesn't have that "clutch", am I doing something wrong by using this alternator? It runs fine so far and puts out slightly under 14V.

 

1. Driving with a bad alternator is a bad idea. Once the voltage drops below 11V, the car will barely run, if at all.

2. Get rid of the mystery alternator with the wrong pulley and order yourself the correct one. It should have never been installed if the stock belt didn't even fit. It will slip, eat the belt, and not charge correctly. You'll end up with even more problems.

3. You're battery is surely toast now from driving on it alone for so long. Replace it so you don't end up stranded.

The correct alternator can be ordered from ECStuning, PureMS, RockAuto, PartsTrain... there are so many places. If AutoZone didn't have it or if you couldn't find one to match, call one of these places for the correct one.

 

1. The alternator ran good.... for a 1 day! The alternator was installed on Friday...broken on Sunday. The battery light came on again, but this time, I assume it was from too high a voltage. The volt meter was reading a little past 14V. The battery light stayed on. when I tried to do an errand about 1.5 hours ago, about 2 miles down the road, I get the "chime" and the yellow battery symbol in the center LED. The headlights GO OUT and all lights in the car go out as well. The hazard lights were the only ones that worked. I stopped to the side of the road (better me than the pregnant wife) and the voltage is waaaaayyy pegged 16V+. I look at the manual and it states "battery voltage too high". Hmmm... interesting.... So I go back to the shop tomorrow...

2. This alternator had a slightly bigger pulley and not the "clutch" pulley. It did fit perfectly. HOWEVER, looking into ordering the alternator, ALL OF THEM seem to have this "non-clutch" pulley. Advance Autoparts, Autozone, ECS (no gots), Rockauto also has this "non-clutch" pulley, etc and they all seem to have the same non-clutch pulley. What gives? The Bentley manual actually specifies BOTH clutch and non clutch pulleys for my "AWM" engine model!!! So obviously, me and my great mechanic are confused.

3. The battery is super good. Load tested and everything....so far...