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      03-08-2009, 07:21 PM   #1
Private First Class

Drives: 2008 M3 Sedan
Join Date: Jan 2009
Location: San Jose, CA

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Installed AA Pulley this weekend... A few notes.

So me and my buddy installed the AA pulley this weekend. I won't say installation was smooth, but I won't blame AA for it - we didn't check belt routing first and getting it right sight-unseen turned out to be more of a PITA than we expected. The instructions were accurate but missing some details that I'd think other folks who want to DIY the install would like to know, so I'd pass along lessons learned.

I'm sorry no pictures, I wasn't thinking of doing a diy before I started.

1) Check belt routing BEFORE you pull off the belts. Make a diagram.

2) Although you won't need to pull off the undercarriage for disassembly, you WILL need it off at least to get the fan housing back installed - and that's assuming you drop *nothing* during the entire uninstall/reinstall, yeah right, so you'll need it off to get at the stuff you lost. The instructions say to pull off the undercarriage but not why.

3) When disassembling the undercarriage, the silver-colored nuts on ether side of the middle undercarriage part (2 per side, 4 total) are NOT to be removed - they're holding the tensioner wires in place. To get the undercarriage off pull all the screws on the underside of the front bumper and undercarriage, inside the front wheel wells, and the three holding it to the aluminum plate beneath the engine. You should be able to get the two 'cups' in front of each wheel off, and from there you can see the tensioner wires holding the middle undercarriage on. Follow the instructions for removal of these wires, which should free the undercarriage. (The instructions say only how to pull the tensioner wires, not where they are nor any warning about not trying to unbolt them from beneath)

4) When installing the new pulley the instructions say to torque the bolts to spec - not what the spec is (I understand why). We guesstimated about 10ft-lbs, maybe 12, but the key here is they're not that tight - do not overtighten (and do not take my word for it - if anyone knows the proper spec here please share! For all I know my pulley's about to fly off into space.).

5) The instructions say to pull off the idler pulley completely during belt removal. It *seems* like you don't have to, but it's definitely easier if you do. The bolt is looooooong and threaded all the way - you'll be twisting it for awhile.

6) It is tough to use standard wrenches/ratchets for relaxing the two belt tensioners. If you're doing it yourself (leaving you one-handed for other tasks) I'd recommend a long ratchet or use an extender to get you the extra leverage to hold it while you futz with the belt. This is particularly helpful for re-install. Wear gloves if you like your knuckles.

7) The fan housing is very fiddly to get back into place during reinstall. You have lots of hoses to clear on the sides, and make sure on the bottom it's not sitting on the hoses. It's best to get someone underneath guiding it down (wear goggles and watch your fingers!) while someone on top lowers it into place, that way the underneath-guy can clear the hoses and snap them back into their guides, as well as make sure the housing's lower two tabs slide back into their holders (you'll see what I mean). Finally, be careful you don't damage the radiator while you're wiggling the fan around.

8) It's not that hard, but for us it was time-consuming due to dumb mistakes. Some of them I hope I've documented here, others were just us being stupid (see: belt routing).