BMW E46 Alternator DIY (voltage regulator)

does anyone know if the same applies to a E30 318 alternators?

just did this. Easy as going to the bathroom. Took like 10 minutes to un-install then 20 to install(forgot how to route the belt lolz)


I think this is a 2/10 for difficulty DIY

One question. I have a 99 328i, does my car have this regulator? Because I have a problem. Here is the thread.
http://forum.e46fanatics.com/showthr...457&highlight=

How do you determine if it is the alternator itself or the voltage regulator??

Originally Posted by nosecone

Hi - my 1st post here. ( '01 Cic )Thanks very much for this info. We were stranded on the highway Saturday PM. Removed the battery and got a ride home & charged it for a couple of hours at a fast rate. While charging, I read this forum & post, so I was pretty sure it was the alternator or regulator. Went back & replaced the battery which got me home - just barely. The dash was lighting up like a Christmas tree as I came up the driveway. After charging the battery over night, the next day I started the car and measured the battery before start (12.57), during idle (11.92) and with the lights on (11.86). No charging going on here! I measured my son's E46 and the same three measurements were 12.8, 13.9. 13.8 volts. So, I ordered a regulator online ($62). I was able to remove the old one from the back of the alternator without removing anything except the air cleaner box thanks to the pictures in this thread - yeah, it took me a couple of hours. Now it's Wednesday and the part is here with a new air filter. Went back in in 20 minutes. The new measurements are 12.31 (off), 14.15 (idle), and 14.09 (lights on). Back in business!! BTW, my plastic air intake for the back of the alternator was full of leaves, a cigarette butt, pieces of wood, and chunk of a styrofoam cup. I intend to put a hardware cloth screen over the inlet ASAP. Wish the original design took care of this. Seems that many times there are problems with stuff like this along with insects and rodents

Thanks again for the info.

Congrats. You saved many hundreds of dollars.

Originally Posted by nuwde

How do you determine if it is the alternator itself or the voltage regulator??

it's either bearings going bad or brushes c/o regulator going bad.

bearings = noise
brushes c/o regulator = low voltage

firefirefire90: Did you only replace the voltage regulator (not the alternator)?

interesting work

Originally Posted by silentak1

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

Also, must i buy a new pulley and belt?

I need to know this before I order parts. Any help?

thanks a million had my car die last friday...batter light on everything on the dash lit up like christmas
ordered the part from pelican came in two days done

I am surprised this thread is still alive and kicking.... Too bad I sold my e46 and do not visit these forums often anymore. 5 series forums are dead compared to e46fanatics....

replacing a Valeo VR tonight.. will update.

currently outputting < 11v

Does anyone know if this is the right Voltage Regulator for my 03?

I dont think so. I have an '01 325i and the regulator listed at Pelican Parts looked different. It stated the part was the same for all '01-'05 with a Bosch 120a alternator. There is a Valeo 90a alternator they put on also.

Several people have asked in this thread if you can replace the voltage regulator while leaving the alternator installed in the car. On my '02 330Ci, I did this last weekend in about 45 minutes.

Once I removed the airbox and moved the power steering reservoir out of the way, I was contemplating trying to remove the alternator. I live in a small town, and no one has the big wrench needed to remove the mechanical fan (yes, I have an automatic). I could have ordered one, but over the Xmas/New Year's break there is no telling how long it could have taken me to get one. Plus, it was cold (even in the garage), and I didn't want to mess with the belts either (they look to be in really good shape). There looked to be plenty of space on the back side of the alternator to remove everything.

I used a small mirror to "see" the nuts/screw I had to remove in order to get the plastic cover off the back of the alternator. Then, you just have to use your fingers to feel for them, or use The Force or something, while attaching the wrench or screwdriver. My biggest fear was dropping one (or more) of the fasteners after removal. Once the plastic cover is loose, I just pushed it out of the way, and had access to the three screws that held the VR on to the alternator. A stubby little Philips-head screwdriver is your friend here, and small hands help as well.

Out with the old, in with the new. Carefully replaced all the screws and nuts, and had the car back together in about 45 minutes. I was delightfully surprised, as I am certainly no expert mechanic. Car runs like a champ!

I didn't get a picture, but there was a very noticeable difference in the length of the brushes between the old and new VR. The only lingering question I have for the electrical experts on here is: why are the two brush lengths different on the old VR? Shouldn't they wear at the same rate? The lengths on the new part are identical. Just some food for thought.


Cliff Notes: you can replace your voltage regulator without removing the alternator (but maybe only if you have an '02 330Ci automatic).

Nice

BTW if anyone is looking for voltage regulator for cheap check out my sig

Word of advice:

If you have a Valeo alternator and plan on replacing the voltage regulator, read this.

When you get your new voltage regulator, there is a black cylindrical cover over where the brushes come out. It is shifted slightly to block the brushes from coming out and blocking a proper installation. Leave it as is until you install the regulator. Once you're done installing, push on that black cap until you hear a SNAP. Now the brushes have come out the regulator and are making contact with the alternator itself.

I missed this step and thought i had a faulty voltage regulator. Turns out the brushes were still up there in the regulator.

Forgot to mention my google search was "alternator 70/120 a bmw sg12b029 25" it was the sg12b029 that nailed it...

Please any handy hints for belts, esp. tensioning. Last time I did this was on a 1972 Fiat

Regards
Matt

All:
After following this thread I'm ready to replace the VR (Valeo) on my '03 325xi wagon (auto). Please confirm if this can be done without removing the alternator, can you please share any step by step tips including required tools.
Where is the best place to source the part, should I look for new, rebuilt or salvage?
This is my first shot at this type of repair so any other advice is welcome, thanks. D