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DIY: N54 Alternator Clutch Pulley (E92)
Published by The Spoon
DIY: N54 Alternator Clutch Pulley (E92)

For diagnosis, check out this video:

I was hearing a very faint squeaking sound coming from my alternator while the car was running. Pulled the belt and found that it wasn't slipping in the reverse direction.

Pulley part number: 12317560678

You can get the same pulley from ECS without the BMW tax:

-Bosch alternator wrench; I got mine from Amazon, labeled as "CTA Tools 8088 Alternator Wrench": http://www.amazon.com/CTA-Tools-8088.../dp/B005OH0LU8
-Ratchet(s) (1/2" drive required for alternator wrench)
-8mm wrench
-17mm wrench (preferably one that can give you good leverage)
-Torque wrench capable of 80 Nm, or 59 ft-lbs
-Torx T20
-Torx T25
-Torx T30
-Torx T60
-Flathead screwdriver

-Breaker bar
-6mm socket
-17mm Flare nut socket
-22mm socket (if you plan on turning the crankshaft to test pulley operation afterwards; highly recommended. No whammies.)

So the unspoken rule of being a backyard mechanic is that in order to fix something, you shouldn't be afraid -- and should expect -- to break both the part that you're fixing, as well as one or more parts that may or may not be related to said part the fix was intended for. You follow this guide and break stuff, I'm not responsible. I'm broke because of this car, anyway. I'd never be able to reimburse you.

1) Remove intake snorkel (Two T20 screws)

2) Unscrew airbox clamp (Flathead or 6mm)

3) Remove diverter valve connector (absent in picture, but it's a simple twist-lock connection)

Radiator fan removal
4) Unscrew radiator fan near passenger side headlight (T25)

5) Unclip radiator fan connector near driver side headlight. Free wire from clips and set aside.

6) Unclip wires and hoses above fan, set aside.

7) Unclip right side of fan from lower chargepipe (I'm not exactly sure how to go about this since I have an aftermarket FMIC, sorry)

8) Unclip radiator fan and pull fan upwards out of engine bay. If you have an oil cooler it's going to be an extremely tight fit, but doable. Pay close attention to the plastic tabs protruding from the front bumper. They'll catch at a couple points while you're lifting the fan out.

Front intake pipe clearance
9) Trace along the front intake pipe and undo two screws (T30; T25 will work in a pinch)

10) Unclip metal line beneath intake pipe.

11) With the intake pipe unbolted, you should be able to move it out and downward enough to fit your T60 bit into the belt tensioner. If your ratchet is low profile, you can just pull the pipe slightly toward you like I did. Turn the tensioner clockwise and remove belt from the pulley.

12) Remove the cap from the alternator pulley with a flathead. Insert the spline socket onto the pulley, put the box end of your 17mm wrench over the socket, and insert the shaft through the center of socket. I forgot to get a picture of the tool on the pulley, but it's pretty self-explanatory once you're at this point. Here's a picture of the tool:

Make sure you're turning the socket counterclockwise and not the shaft, such that you're rotating the pulley counterclockwise. The 1/2" drive ratchet attached to the shaft should be going clockwise, in the tighten direction.

12a) I wasn't able get enough leverage using the 17mm wrench with my spaghetti arms, so I used a 17mm flare nut socket and a ratchet instead. That sucker was on tight. When it finally broke loose the socket went flying into some deep recess of my garage. I seriously thought I had broken something.

New ECSTuning pulley on left, old pulley on right.

13) Install new pulley and torque to 80 Nm (or 85 Nm*).

*According to workshop-manuals.com, the pulley is to be torqued to 80 Nm:
However, the documentation from INA that comes with the pulley specifies 85 Nm, so use your own discretion.

New pulley installed (don't forget to put the cap back on)

13a) Check that the pulley is operating correctly as shown in the video at the top.

14) Reinstall serpentine belt. Routing diagram:

Belt installed:

15) Rotate the crankshaft clockwise (22mm) a few times and observe belt to make sure there aren't any hiccups (as a backyard mechanic, hiccups can also mean explosions) in your install.

Now put it all back together. If there are leftover parts at the end, it just means you're smarter and more efficient than the engineers who designed it. Enjoy the weight savings*, yo.

*weight savings may have the side effect of hiccups.
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By ucdbiendog on 08-19-2015, 07:12 PM
great DIY!
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By parksjm7 on 11-24-2015, 02:21 PM
Thank you for this DIY. I'm about to order the Gates brand pulley and undertake this myself. Did you have to uninstall the alternator, or were you able to replace the pulley without taking the alternator off?
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By The Spoon on 11-24-2015, 04:53 PM
Member reviews
Difficulty [ 1 = Difficult ]
Cost [ 1 = Expensive ]
DIY Clarity [ 1 = Not clear ]
Average 20%
Removal of the alternator is not necessary
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