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      10-04-2015, 11:10 AM   #1
anom3
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DIY : E92 M3 Alternator Replace

A few weeks back I ordered a new alternator.

A few reasons I ordered it, mainly:

A) I ordered an "upgraded" 220AMP one since I have a rather powerful aftermarket amplifier.

B) I noticed when my vehicle is 100% warmed up my idle wont stay at 550/600. It'll bounce up to 800 rpm after about 10 seconds. I know for sure its not my battery as its nearly new (about 8 months old). I also ran some tool32 tests and the IGR system says its falling back to "IGR-Medium" quite quickly.

C) On cold starts I have a rough sounding noise I have traced to the alternator clutch. I am 100% sure its related to the alternator clutch as I have made some changes in the JBE and CAS modules and been able to delay this noise by 0.5 to 1.0 seconds.

So anyways, the procedure is quite simple. I wont post detailed instructions how to do every step as most of it is on here already, but:

Step 0) Unplug your negative cable from your battery. Essential as you will have a loose + cable once the alternator is out.

A) Remove the air filter housing. NOT the pleneum. Just the air filter housing lid and bottom and the hose connecting it to the pleneum. You should now be able to see the alternator quite well.

B) Remove the radiator fan. Its attached by one torx screw on the left side. There is also a hose "clipped" to the bottom of the fan. You can unclip this hose by sticking your hand in through the air intake on the very very bottom of the vehicle (under the car). Its on the passanger side. Feel around, its there. Removing the fan will seam a bit impossible to anyone whos a novice at this vehicle DIY stuff. It will go. It needs a bit of force, and you need to do your best to get the fat radiator hose to allow you to get it out. Also make sure to (duh) unclip the electrical connection to the fan on the passanger side.

C) So at this point you have a very clear view of the alternator. Next you need to take the belt off the alternator. All that you need to do is use a 14mm to retract the tensioner and slip the belt off. Once its off, put it to the side and out of the way. Thats all there is to do regarding 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.

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!).

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.
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      10-05-2015, 10:00 AM   #2
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Quote:
Originally Posted by anom3 View Post
A few weeks back I ordered a new alternator.

A few reasons I ordered it, mainly:

A) I ordered an "upgraded" 220AMP one since I have a rather powerful aftermarket amplifier.

B) I noticed when my vehicle is 100% warmed up my idle wont stay at 550/600. It'll bounce up to 800 rpm after about 10 seconds. I know for sure its not my battery as its nearly new (about 8 months old). I also ran some tool32 tests and the IGR system says its falling back to "IGR-Medium" quite quickly.

C) On cold starts I have a rough sounding noise I have traced to the alternator clutch. I am 100% sure its related to the alternator clutch as I have made some changes in the JBE and CAS modules and been able to delay this noise by 0.5 to 1.0 seconds.

So anyways, the procedure is quite simple. I wont post detailed instructions how to do every step as most of it is on here already, but:

Step 0) Unplug your negative cable from your battery. Essential as you will have a loose + cable once the alternator is out.

A) Remove the air filter housing. NOT the pleneum. Just the air filter housing lid and bottom and the hose connecting it to the pleneum. You should now be able to see the alternator quite well.

B) Remove the radiator fan. Its attached by one torx screw on the left side. There is also a hose "clipped" to the bottom of the fan. You can unclip this hose by sticking your hand in through the air intake on the very very bottom of the vehicle (under the car). Its on the passanger side. Feel around, its there. Removing the fan will seam a bit impossible to anyone whos a novice at this vehicle DIY stuff. It will go. It needs a bit of force, and you need to do your best to get the fat radiator hose to allow you to get it out. Also make sure to (duh) unclip the electrical connection to the fan on the passanger side.

C) So at this point you have a very clear view of the alternator. Next you need to take the belt off the alternator. All that you need to do is use a 14mm to retract the tensioner and slip the belt off. Once its off, put it to the side and out of the way. Thats all there is to do regarding 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.

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!).

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.
I thought that's the idle speed - 800 rpm. To me that's perfectly normal, and it has been like that from day one.
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      05-08-2016, 12:42 PM   #3
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Quote:
Originally Posted by anom3 View Post
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 the write up and the torque spec! Have your issues been fixed?

I believe the TIS underbody protection removal is to allow for reattachment of all the hose clips to their respective hoses after re-installing the fan shroud. There are quite a few connection points that are very difficult to reconnect otherwise. Here is a photo that shows some, but not all of those hose clip connection points:

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      05-08-2016, 01:16 PM   #4
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I think my alternator just went out on me... Was looking for a DIY! Thanks
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      05-08-2016, 09:45 PM   #5
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Same here, pretty sure my alternator went bad also. Good source for a alternator? Any Tips on testing the alternator?
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      04-10-2017, 02:24 PM   #6
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Thanks so much for this guide.

When I get the bolts out and it comes time to wiggle the alternator out, is it supposed to be ridiculously hard to get out? I've been trying to get it out for the past two days by wiggling it or using a 2x4 to pry it. I've had about ten different people try to get it out but it seems to just be pivoting around where the bottom bolt goes in (I've already taken out both bolts). It's really stuck in there.
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