Replacing Noisy Idler Pulley

[IconJB]

I am replacing a noisy idler pulley on my 530i. I really don't want to pull the shroud and fan off. I think I can get access by just removing the upper radiator hose.

Would the best way be to loosen the idler pulley with the belt on, and then remove the idler pulley by unloading the tensioner? I want to avoid completely removing the belt first, as it is going to be a tight squeeze rerouting it, with the fan and shroud in place. I can then do the opposite to reinstall the new idler, by fastening it first, and then unloading the tensioner to wrap the belt back around it. Thanks

JB

[aa240sx]

subscribed to this thread. I'm curious about this job myself as I'm about to tackle it this weekend though in my case I am changing the belts and waterpump out. Also, I'm a bit strapped for cash, so I only plan to pull the pulleys off, repack the bearings with grease and hope that gets rid of the noise rather than replacing them or the hydraulic tensioner. In my case, I've sort of isolated the noise to - pulleys (re-grease), - belts (being replaced), - water pump (being replaced).

[cnn]

Info for 1998 528i is here, 2001-2003 models are similar:
http://www.bimmerboard.com/forums/posts/199986

IconJB, To access the pulleys for servicing:
1. Remove Fan Clutch and set it inside the Fan Shroud.
2. No need to remove Fan Shroud.
3. Apply force Clockwise on the "lower" Pulley (aka Tensioner Pulley) to release tension on the drive belt and slip the belt off.
4. Now you see the "Idler pulley", check to be sure you have Torx or Allen screw and remove it. Straightforward:




aa240sx, If you are strapped for cash. Info on re-packing the pulleys is here:
http://www.bimmerboard.com/forums/posts/200161
1. Note how the pulley is assembled, including washer orientation for re-installation.
2. Use a picking tool and gently remove the seal and you will see the bearing. There are a total of three (3) bearings: 2 on the tensioners and on deflector (or idle pulley), while there, you may as well grease all three of them:




PS: You can dip the bearing in a small container containing gasoline to rinse of old grease. Then pack new grease in and re-install the seals.

[spseminara]

Honestly taking the fan off isn't as scary as it sounds. Plus it makes the job so much simplier.

[IconJB]

I'm not worried about taking off the fan. It's the shroud that was a pain when I did the water pump and thermostat.

CNN - I think you have your fasteners backwards - the Torx is on the tensioner and the hex is on the idler, right?

[cnn]

The bolt: it depends on the year/model, sometimes Allen, sometimes Torx (BMW varies with supplier for nuts and bolts).
Check to be sure. Use a mirror and flashlight.

[Flybot]

It will be such a PITA without the fan and shroud removed. If you take the fan off your two plastic rivits away from lifting the shroud out.
Look at the DIY on alternator replacment on a 6 cyl.