BMW E46 Alternator DIY (voltage regulator)

Hello everyone,

I saved so much money working on my BMW and all thanks to e46fantatics! Thank you everyone for posting! I feel that I have to give something back to the community. So here is my first diy guide.

I searched this site, google, could not find how to change voltage regulator and brushes on e46. Decided to do it myself.

Initial problem was that alternator would give only ~10.3V if I had my lights and AC on. That drained my new battery. As my car is 2001 (06/2000 production), I decided that it was either brushes or voltage regulator. Ordered Voltage regulator (it comes with brushes) from pelicanparts, it is $53 (compared to $212+shipping on re manufactured Bosch alternator).

There is a good guide how to replace the alternator


here,


so I won't repeat it. When you have your alternator out, there is a plastic back plate. You have to remove one screw (#3 in picture and two nuts (#1 an #2). #1 is under this rubbery plastic cover, use screw driver to pry it out.

- The nut holding down the positive cable is 17mm
- #3 is a Philips screw
- #1 and 2 are 15mm nuts (deep wall socket is most likely needed)




After you remove the cover, you should find ..... this




I found all sort of stuff - leaves, paper, cigarette butts, you name it. The voltage regulator is connected with 3 screws and slides out after, no clips.
My old brushes were worn, but not to the extent that alternator would not work, one was shorter than the other one. Go figure...





The whole process takes about 10-15 minutes (after you have alternator out). It is cheaper that buying refurbished alternator and it is way cheaper than taking to the dealership. If you alternator does not make any noises (ball bearings) changing just the regulator will save you lots of money. I believe it is easier to do this than remove the pulley while switching alternators... After I changed the regulator, with long beams on, AC on it runs 13.6V to my battery, I believe that is within specs of 13.5 -14.5V. Maybe on the lower side, but hey, its not 10.3V like before.

I hope that helps someone.

Part number from pelikan $53 12-31-7-559-183-M14 link

very nice...so you keep the voltage meter on the battery not the front of the car right?

Yes, at the battery. At least I did it like that. The car is back

[QUOTE=Girmis;8072664]My old brushes were worn, but not to the extent that alternator would not work, one was shorter than the other one. Go figure...


Where are the brushes located? Do you remove another part or can you see them after you remove the regulator? Since brushes are worn, are you able to replace them?

not sure about replacing just the brushes, I did not see those for sale anywhere... It is just called the brushes, actually it looks like metal pieces (third picture, just above my finger, to the left of that cut out circle.

Nice write up.

I got this question:
Saw that you pulled your alternator. Is there any way to tell from the top if it's a Bosch or Valeo?

The answer:
Yes, you can, but you will need a mirror and a light. There is a sticker on the black plastic back plate (you can see that in the first picture - it looks like some bar code). It is faint on my alternator, but it is readable. I would suggest removing air filter housing (easy - 2 10mm bolts). You might be able to see even without taking it out, but it will be very very hard to get down to alternator ....

So the new brushes come with the new regulator?

I bought the regulator and it came with brushes I did not see the brushes for sale.

Does the new BOSCH alternator come with the regulator? Or must it be transferred?

Also, must i buy a new pulley and belt?

I am in a similar position right now.
The stealership iv giving an estimate of $800 for replacing the Alternator.
I have decided to Do it Myself after reading all the posts here.

The question now is where do i buy the Alternator from?
I can locate these at ******************.. are these good.

Bosch alternators

Neo

my problem is similar, the regulator are overcharge. I need to find an used alternator or chip voltage regulator

I just got done putting a new voltage regulator on the Bosch alternator for my 2002 330ci and it works great! It's putting out 14.3V! I've got 67K on the car and the bearing and the rest of the alternator are in good shape. I did use a wire brush to clean any corrosion on the copper wiring found under the cover. I would highly recommend this repair. Also, a lot of the larger auto parts stores will do a free alternator and battery test.
http://www.autozone.com/in_our_stores/free_testing.htm
Thanks for the post! I saved over $700.00.

Do you think you could have replaced the voltage regulator without removing the alternator? Is there enough clearance to remove the air-intake assembly (screwed to the alternator) and wiggle the regulator into place?

Originally Posted by visions1

Also, a lot of the larger auto parts stores will do a free alternator and battery test.
http://www.autozone.com/in_our_stores/free_testing.htm

I don't know about everyone else, but when my charging light went off the other day, this was the first thing I did, pull the alt and get it load tested. My alternator tested good at both autozone and o'reilly, so I slapped it back in the car thinking it was a different problem. After pouring over these forums and tracing that green wire off the alternator (not the one that goes to the light) I went with my gut and bought a new alternator anyways (after unhooking the lug and checking voltage on my own). Now the car is fixed. The testing setup at both parts stores gave a false reading.

As a side note, the alternator at O'reilly was only $200 + core with a lifetime warranty. Now I hate having a "china" sticker on my car as much as the next guy, but if you're frugal, I figured I'd throw that price out there.

Originally Posted by RotaryBzzz

Do you think you could have replaced the voltage regulator without removing the alternator? Is there enough clearance to remove the air-intake assembly (screwed to the alternator) and wiggle the regulator into place?

As for that, I doubt it. It might be possible, but with enough wiggle the alternator came out of my car with no hassle at all. I'd say just pull the alternator and swap the regulator, it would be easier than fuggering with the low clearances behind it.

i got the alternator out. i will just go to the wreckers and get one from a wrecked car. Easy removal. I would think installation is very easy too.

i got the alternator out. i will just go to the wreckers and get one from a wrecked car. Easy removal. I would think installation is very easy too.

I would recommend pulling the alternator out so you can check the bearings and be sure it is still in good enough condition to use with a new voltage regulator.

Hi Everyone, I own a 2003 E46 318i (N42 valvetronic) with 125 000 km.

I hope someone could help me a bit. I have been having this problem for the last 6 months or so.
My alternator lights comes on for a second or so togther with the a drop in revs and a jerk.
I have replaced my battery, still the problem exists.
I have recently reconditioned my alternator, so new Regulator, new pulley, new bearings. But still the problem exists.
But I must say the IDLE is alot smoother now.

I also had my car hooked up for Diagnostics , it states that Cylinders 1 and 2 are running at 60% effeciency.
So now I'm not sure if the engine is cutting off for some other reason which causes the alternator to stop spinning
for a short while which lights up the alternator light.

Or the alternator core is dying causing the alternator to behave erratically.

Currently on idle my alternator pushes out 14,3v but after driving around a while it drops to 13,3v.
And the problem always happens after driving around for 20 minutes or so when the engine is hot.
So it's possible the core is dying once it gets hot.

But the strange part is that after it jerks and the light come on for that second, then on most occassions it's fine for th rest of the journey.
Several times it stwitched off at the traffic lights. But starts up fine again.

It seems like if the REVs are high enough it does switch off but kicks itself into life but with REVS low like at the traffic lights it can't kick itself, so it stalls.

Does any of this make sense. I really don't want to spend more money on a new alternator if it doesn't solve the problem.

Any help would be appreciated greatly.

Can the alternator die just for a second or so, just enough to stop energy to the plugs which causes the jerk or

is it possible the engine cylinders 1 or 2 cutoff due to bad plug etc, causing a stall or jerk which also causes the alternator light to flash ?

Does the voltage drop on the alternators when it gets hot ?
How low can the voltage go before it causes problems ?

You would think that if the alternator voltage drops below a certain point for a second or so that the battery could provide the energy required without the engine missing a beat.

BMW_E46_SA,

Check your wire connections (ground wire to the car body, wires to alternator and battery, etc.). Make sure they are clean and tight.