DIY : E92 M3 Alternator Replace

msan wrote

Probably On a lift. But this was the key info...

most important key is remove the Alternator's top bolt about quarter inch and remove the bottom bolt about half inch. And get a hammer and start hitting the bottom bolt like you are hammering a nail! There is the back part of this bolt has to move quarter inch while you are hammering! And you will see that alternator start getting loose. And then jiggle the alternator and see how loose it become. If it is not that loose hammer back again! Once it is loose remove regardless of order bottom or top bolt and put the alternator to the bottom of the engine tray!

Yes, thanks, I read that, and it reminded me of the posts in this thread from the user who I think also points to the same bolt in the back as the solution to the removal problem. I look forward to seeing what happens....

RedCardinal wrote

Yes, thanks, I read that, and it reminded me of the posts in this thread from the user who I think also points to the same bolt in the back as the solution to the removal problem. I look forward to seeing what happens....

Here is a great read regarding why the alternator doesn't come out after removing the bolts.

http://www.bimmerfest.com/forums/showthread.php?t=740121

Here is a pic of the "sliding nut" that "locks" the alternator in place and needs to be tapped out...

RedCardinal wrote

codinge90 wrote

I did my alternator twice a few months ago. First time I used an autozone one, threw and alternator code to returned it and got an oem one. First time it took like 5 hours second time took me 30 minutes. Hardest part is getting the actual alternator out. What you'll need to do is get some wd40 or something to lube up where the bolts slide into on top and bottom of the alternator, let it sit and literally use a crowbar and yank it out. Depending on how old the car is, it'll be budged in there. Mind took an actual crowbar to get it out, you really gotta pull and push until either the top or bottom slides out. Everything after is simple

thanks for the tips. did you follow op's method of getting to it - remove air box and radiator fan?

thanks again.

Yes the fan will be a bit of a pain to get out, I broke a clip on the right side but just take your time and apply pressure lifting up.

msan wrote

Here is a great read regarding why the alternator doesn't come out after removing the bolts.

http://www.bimmerfest.com/forums/showthread.php?t=740121

Here is a pic of the "sliding nut" that "locks" the alternator in place and needs to be tapped out...

super helpful, thanks!

The two alternator-to-mounting bracket bolts are M10, silver colored (8.8 ZNS),and require a torque spec of 38NM (28 ft lb). If for some reason your car has yellow (ZN) bolts that have 8.8 on the head (may be possible if you have an aftermarket alternator that came with new ZN bolts) the torque spec would be higher at 47NM (35 ft lb).

Often its the controller/regulator that goes on the blink and needs changing. BMW don't sell this for anything reasonable but any valeo dealer can get you the regulator.

When I looked, the regulator was about $140. I bought the alternator with regulator for $230.

pbonsalb wrote

When I looked, the regulator was about $140. I bought the alternator with regulator for $230.

That's what I did, I just straight out replaced the entire alternator. That's the only way I got rid of that Alternator Communication error

dty3 wrote

For the original DIY: I just replaced this and I am not sure how the OP did it, but there was no way that I could it....here is a quick update on the steps I would add.

Add-in: I would release the belt tesioner (the middlle one) by loosening bolt directly above it. This will release the tension on the belt.

D) Next you need to remove 2 16mm bolts holding the alternator. Double check they are 16mm as I don't recall if they were 14mm or 16mm. One is right at the top very visible, the next one is hidden on the bottom of the alternator right around where the belt tensioner wheel is. Feel around with your finger, its there. Unscrew and pull out both bolts.

Add-in: Wiggle out the alternator prior to un-clipping the connector and removing the nut.

E) Next unclip the 2 pin electrical cable plugged to the back of the alternator.

F) Now its time to wiggle the alternator out. Yes, leave the B+ cable attached for the time being. There is just not enough room to get to it with the alternator in place.

G) So at this point the alternator should be out of its place, but still sitting at the bottom of the engine bay. Unscrew the B+ cable at the back. Its a 17mm bolt from what I recall.

H) The alternator is ready to be pulled out. Quite a bit of room to get it out, you will have no trouble.

This is as far as I am right now (taking a break between removal / reinstall) but reinstall looks opposite of removal. A couple of things I will do before reinstalling:

A) Give the B+ cable and its bolt a good sanding to ensure a good connection.

B) The "slots" that hold the alternator I will probably clean with WD40 and give a tiny tiny greesing just to make it slide in there easier (thats what she said!).

Add-in: Reinstall the alternator first, starting with the lower bolt, making sure the lower bolt passes thru the hole on the block. then screw in the upper bolt.

Add-in: Place the belt in the correct postion, put the screw back into the tensioner, once this is complete, remove the cap from the tensioner pulley with a screw driver, you should see a 14mm bolt. For this step I recommended getting someone to help you with this. I used a short extension attached to a 14mm socket, placed it on the 14mm bolt and rotated it clockwise, this will release the tension on the belt...this is where your helper comes in, while i was holding the pulley in position, your helper wiggled the belt into place (this was tedious), once in place release the tensioner and your done. now you just reinstall the fan, clip the hoses from the bottom and reassemble the air intake....

Final notes:

A) The torque on the B+ lead should be 19NM according to BMW.

B) The BMW TIS states that the underbody protection needs to be removed. I found there is absolutley no need to do this.

C) Will post if a new alternator fixes some of the issues mentioned at the start of this post.

Thanks for taking the time to add the updates, they were really useful for me today getting the damn thing removed.

I just finished my alternator replacement. A couple things to add:

Use a long 14mm angled close ended wrench for the belt tensioner and start around the 3 o'clock position and push down. That moved the tensioner much easier than trying from 12 o'clock to 3.

Lining up the bolts with the new alternator was a huge PITA. I used a thick screw driver to get the bottom lined up (moved around which trying to pass through the bolt holes). That helped me stabilize it a bit and I screwed in the top one first then removed screwdriver and screw in bottom bolt.

Lastly when trying to remove the alternator it does not have a bushing like stated above. It has machined edge on the inside and it's just a tight fitting alternator. Best option for me was to use a pry bar between the engine block and the alternator, while wiggling alternator with one hand slightly pry with the other. I didn't need alot of force which was good so I didn't break anything.

codinge90 wrote

Yes the fan will be a bit of a pain to get out, I broke a clip on the right side but just take your time and apply pressure lifting up.

No way on earth was that fan coming out. The plastic fan clip on the right broke also I snapped off the upper radiator vent pipe fitting on the upper radiator hose. It just snapped right off when the fan touched it as I was lifting so now I have to buy an entire new upper radiator hose with that fitting and a new vent pipe to the overflow tank. I really dont see why the fan needed to come out. it looks like the alternator would be removable without taking the fan out. Are you guys really removing the fan without breaking crap or removing radiator hoses???
Just seems impossible on a 10 year old brittle car to be bending hoses and fittings and not expect them to snap off.
seriously.

It does come out but you have to disconnect the bolt holding a pipe to the fan shroud and disconnect the clipped in hoses. You also have to wiggle and tilt. And you have to unclog and hold the small reservoir hose to a position forward of the shroud and hold the upper hose to the side. Since it is a bit tricky, I can see how there could be problems.

My car is a 2008 with just over 100k miles and I have had the fan out half a dozen times. It is never fun and I always worry about breaking that small nipple. I will likely replace the cooling system hoses in the next year. 10 years is a fair lifetime.

pbonsalb wrote

It does come out but you have to disconnect the bolt holding a pipe to the fan shroud and disconnect the clipped in hoses. You also have to wiggle and tilt. And you have to unclog and hold the small reservoir hose to a position forward of the shroud and hold the upper hose to the side. Since it is a bit tricky, I can see how there could be problems.

My car is a 2008 with just over 100k miles and I have had the fan out half a dozen times. It is never fun and I always worry about breaking that small nipple. I will likely replace the cooling system hoses in the next year. 10 years is a fair lifetime.

The new alternator is installed.

There were a few issues, I'll try to list the major ones.

1) do not break off the bleeder valve nipple on the upper radiator hose if you remove the fan assembly. It requires you to bend it and it will snap very easily if you have an older car (done that, new hoses on order)
1a) do not break off any of the fan shroud clips, they are brittle from years of heat and snap if you touch them. I broke one.
2) use cardboard to protect the radiator once you have the fan out as you will be slamming all kinds of tools around near it.
3) getting the old alternator off -- The bottom bolt does truly need to be backed off about 1/4 inch and then hit with a hammer to knock the rear captive nut back just enough to make it clear then rock like hell and it, remove the rest of the bolt and it will come out if you paid your dues. This part took me nearly an hour to figure out even though I knew the tricks.
4) --- this was the worst part for me --- the 14mm box wrench needed on the belt tensioner bolt continued to slip off. any 14mm Box wrench is pretty short, so the box wrench I had was barely enough even with a rag wrapped around it because it was cutting my hand with the force required to move the tensioner. A socket wont work because it hits a metal pipe right in front of the bolt as the tensioner travels you will hit the pipe and cant get full travel. You will need every last inch. A box wrench is the only way. Maybe they make a 12 inch long 14mm box wrench, that would be cool. I was considering cutting a piece of pipe to extend the box wrench to get more leverage.
5) While using said inadequate short 14mm box wrench on said belt tensioner, be very careful putting the belt back on. I ended up busting a finger pretty seriously because the wrench slipped pinning my finger between the belt and the alternator pulley. I had to dig out the box wrench from the bottom of the chassis and tension the pulley to get my finger back from under the belt. You've been warned. It's not pretty.
6) the new bottom bolt will go in with some persuasion make sure it's lined up and give it a smack and then start threading into the rear nut.
If I forgot anything please feel free to correct me.


Also you may all be interested in this:
The alternator (Vaelo BMW original 2009) that I removed had a very obvious failure, and actually appears to be an easy fix.
There is a plastic cap on the voltage regulator which contains two brushes which ride on the commutator. In my case, and seems to be a very common issue, the brushes were totally shot to the point they were no longer protruding from the plastic housing and were unable to make contact with the copper on the commutator. They were in fact stuck in place from built up carbon dust and worn down. Also the commutator was completely gummed up with this graphite grease/powder from them wearing. Bottom line -- it was no longer making any connection so the regulator said "Screw this peace out I'm done I don't know what to do" and stopped working. I do not see any reason that you could not clean up the commutator and replace the brushes and get another 10 years out of this alternator. I will be doing so even though I replaced it with a new alternator. I've seen the repair for 7 bucks you can get brushes and solder them in if you have decent repair skills and can work a soldering iron.

I just thought I'd let you all know of the root cause of the failure and that it appears to be easily fixed, or for a few bucks more just buy the whole regulator assembly.
Due to the 10 year age I decided to buy the whole alternator since it was a deal at $250-$280

There is a guy in the past 6 months who bought a regulator for about half the price of a new alternator, but it did not fix the problem. I can’t recall whether he identified another issue, but he ended up buying a new alternator as well. Trying the brush change would be worthwhile to some since it is much less than a regulator, but if it does not work, you are doing the job over again. At 10 years, I am OK with buying new parts.

TX wrote

pbonsalb wrote

It does come out but you have to disconnect the bolt holding a pipe to the fan shroud and disconnect the clipped in hoses. You also have to wiggle and tilt. And you have to unclog and hold the small reservoir hose to a position forward of the shroud and hold the upper hose to the side. Since it is a bit tricky, I can see how there could be problems.

My car is a 2008 with just over 100k miles and I have had the fan out half a dozen times. It is never fun and I always worry about breaking that small nipple. I will likely replace the cooling system hoses in the next year. 10 years is a fair lifetime.

The new alternator is installed.

There were a few issues, I'll try to list the major ones.

1) do not break off the bleeder valve nipple on the upper radiator hose if you remove the fan assembly. It requires you to bend it and it will snap very easily if you have an older car (done that, new hoses on order)
1a) do not break off any of the fan shroud clips, they are brittle from years of heat and snap if you touch them. I broke one.
2) use cardboard to protect the radiator once you have the fan out as you will be slamming all kinds of tools around near it.
3) getting the old alternator off -- The bottom bolt does truly need to be backed off about 1/4 inch and then hit with a hammer to knock the rear captive nut back just enough to make it clear then rock like hell and it, remove the rest of the bolt and it will come out if you paid your dues. This part took me nearly an hour to figure out even though I knew the tricks.
4) --- this was the worst part for me --- the 14mm box wrench needed on the belt tensioner bolt continued to slip off. any 14mm Box wrench is pretty short, so the box wrench I had was barely enough even with a rag wrapped around it because it was cutting my hand with the force required to move the tensioner. A socket wont work because it hits a metal pipe right in front of the bolt as the tensioner travels you will hit the pipe and cant get full travel. You will need every last inch. A box wrench is the only way. Maybe they make a 12 inch long 14mm box wrench, that would be cool. I was considering cutting a piece of pipe to extend the box wrench to get more leverage.
5) While using said inadequate short 14mm box wrench on said belt tensioner, be very careful putting the belt back on. I ended up busting a finger pretty seriously because the wrench slipped pinning my finger between the belt and the alternator pulley. I had to dig out the box wrench from the bottom of the chassis and tension the pulley to get my finger back from under the belt. You've been warned. It's not pretty.
6) the new bottom bolt will go in with some persuasion make sure it's lined up and give it a smack and then start threading into the rear nut.
If I forgot anything please feel free to correct me.


Also you may all be interested in this:
The alternator (Vaelo BMW original 2009) that I removed had a very obvious failure, and actually appears to be an easy fix.
There is a plastic cap on the voltage regulator which contains two brushes which ride on the commutator. In my case, and seems to be a very common issue, the brushes were totally shot to the point they were no longer protruding from the plastic housing and were unable to make contact with the copper on the commutator. They were in fact stuck in place from built up carbon dust and worn down. Also the commutator was completely gummed up with this graphite grease/powder from them wearing. Bottom line -- it was no longer making any connection so the regulator said "Screw this peace out I'm done I don't know what to do" and stopped working. I do not see any reason that you could not clean up the commutator and replace the brushes and get another 10 years out of this alternator. I will be doing so even though I replaced it with a new alternator. I've seen the repair for 7 bucks you can get brushes and solder them in if you have decent repair skills and can work a soldering iron.

I just thought I'd let you all know of the root cause of the failure and that it appears to be easily fixed, or for a few bucks more just buy the whole regulator assembly.
Due to the 10 year age I decided to buy the whole alternator since it was a deal at $250-$280

I just replaced the alternator myself and want to thank everyone that has collaborated. I wish I had read this post but got too excited and it was a bitch to remove.

If you don't happen the lower bolt, get yourself a can of WD40 with the flexible tip. It will become a life saver and will really help getting the alternator out. It really took me like a day and a half (5-10 minute intervals) to take it out so made the job harder than it needed to be.

Also, I highly recommend you get a serpentine belt tool. You can get a loner from autozone or advance for free. It will help to move the tensioner without damaging the bolt, which I damaged a little bit by using a regular ratchet and 14mm socket.

Bumping this thread. I just did my alternator and a HUGE thank you to everyone on this forum for the advice, pictures and the great DIY. Some things to add that I found helpful:

1. When removing the bolts on the alternator, remove the bottom bolt first and spray a little PB Blaster using the little red straw into the bottom bolt hole so that it reaches the circular sliding section on the other side of the nut. Let it sit for ten min or so and reinsert the bolt and turn it by hand about 4 times until its snug into the sliding bolt. GENTLY tap the head of the bolt with a small sledge hammer until the alternator pivots fully on the top bolt when you remove the bottom bolt. Remove top bolt and use a large flat head screwdriver to gently push the alternator out of it's mounting bracket and it will easily slide out. Pull the alternator out with the pulley facing up after unplugging the cable and lift it out.

2. When reinstalling the alternator, sand the 17mm nut lightly so that it is shiny and clean. Lower the new alternator into place like it was removed with the pulley facing up. Reinstall the B+ cable and plug before getting the alternator in place and reinserting the bottom bolt, tightening it enough so that the alternator can pivot now from the bottom bolt.

3. Be sure to check the individual hydraulic tensioners, (these are common failures on higher mileage E90/92/93 M3s) and inspect each pulley for any play, noise or wear if you choose not to replace them.

4. GO SLOW and be patient. This is a DIY with very little space to work, old coolant lines and plastic brackets along with your radiator. Use proper lifting techniques, have patience and this job is easy. It took me a little under two hours from start to finish.


I hope this helps anyone doing this DIY and thank you ALL again for the awesome thread.

Ok so I just had the same problem with my e93 M3 and decided to take on the project myself to save some extra bucks to put towards Mods....Big shoutout to all of you guys for sharing the replacement instructions (I truly luv my M community lol).....With all that said, I want to share a major tip that will make this process soooooo much easier in how to get the alternator out once the screws are removed and the wire in the back is unclipped (not the negative - black wire) ......if your old alternator was like mine, that joint would not budge no matter how much I rocked it up and down and rugged on it.....the trick that I used was to take a small conventional hammer and wedge the teeth ( backside of hammer) into the the vent side ( the part off the alternator where you can see the copper wire windings) of the alternator and lay the head of the hammer up against the engine block (specifically on the round hump where the Tension pulley (idler arm) sits....once I got the hammer into place I stood on the driver side of the car and pushed the hammer handle towards the passenger side, and pop went the Alternator out of its place........sidebar I did spray a bit of WD-40 in between where the front of the Alternator and the Engine block meets (thats the spot on the alternator where you have to feel for the screw on the bottom because you can’t physically see it ....the long screw side) ...........I hope this is of great help to you guys, any questions just hit me up , I’m always down to help out... Stay Blessed! peace ✌️

I will be giving this a shot this weekend

Just did my alternator a couple days ago, the fan can be a little tricky to get out but if you take your time it will come out easily without breaking any clips. The alternator was a bit more finicky but after a bit of wiggling back and forth and side to side I was able to get mine out. Putting in the replacement was a breeze as was getting the fan back in with no broken clips or tabs.

irokwrx wrote

I will be giving this a shot this weekend

Just wondering if you got to the alternator? Didy ou have that sliding nut at the bottom?

msan wrote

Just wondering if you got to the alternator? Didy ou have that sliding nut at the bottom?

Yep, it was SUPER easy. Took off the top bolt backed out the bottom about an inch and a half and taped it back in and the unit literally fell out. SO easy! the bad thing is my footwell module failed when I hooked the battery back up. But yes tap it back and IT COMES RIGHT OUT

Old thread, but what a good one. With all the tips in this thread, this was easy as pie. I spent more time fighting with the intake than nothing else.