Replaced both belts, tensionsers, tensioner pulleys and idelr pulley today.

[808MGuy]

The hardest part was removing the fan assembly which barely fits past on the radiator hoses. I actually ended up breaking off the nipple on the upper radiator hose coming from the thermostat housing. The nipple connects to the vent pipe coming from the coolant expansion tank. That nipple faces in towards the fan housing an as you pull up its near impossible not to get caught on it. Super glued it back together so I could at least start the car and run it to make sure all the belts are on correctly but I won't drive it until I replace the hose assembly.

Couple things to point out:

1. You need a long handle ratchet to move the tensioners. I used a 12" long 3/8" drive ratchet but longer would have been nice. I takes a lot of leverage to move it as much as you need to. Taking off the hoses are not so bad but putting the new ones on really needs full movement of the tensioner. I needed to use a pipe extension on my ratchet handle to make it work.

2. 12 pt sockets or offset wrenches are helpful for the tensioners. The amount of leverage and the angle if access makes the offset wrench a great tool for that purpose. You can use a 3" ratchet extension but my 6 pt socket kept slipping off. Going to a 12 pt wrench made a big difference.

3. I couldn't find exact specs for a lot of the bolt but I did 24 ft-lbs for the idler pulley, 18 ft-lbs for the tensioner bolts, and 89 in-lbs for the water pump pulley bolts which need to be removed to access the top bolt for the alternator tensioner.

4. I actually jacked the car up and removed the underbody shield for this job because I was planning to change it at the same time but this is very helpful as I dropped tools many times that would have ended up on the shield but they fell right through. The only downside is that I've found once removed, the clips and screws tend to damage the shield and it might not be possible to put it back without replacing it. The problem I had with the shield is that the clips used to secure the shield tend to turn on dig into the soft material eventually tearing it. I wish they would open up those holes on the clips a little more so that you don't need so much torque to get the screws through.

[Dannys M3]

I don't know why they made the electric fan and hose tolerance so tight. I also broke off the overflow nipple and used a marine epoxy to stick it back on. I have the replacement but the fix is holding. The first time I took the belts off I made a cheater bar from some hollow metal tubing. The second time I went to Harbor Freight for a longer handle ratchet.

[808MGuy]

I would have glued mine back on too but the nipple fell into the black hole of the engine bay and I ouldn't find it.

[Dannys M3]

I put an arrow for other people to see the nipple we're taking about that is easy to break.

[808MGuy]

Finally got my replacement hose in last night and replaced it. Now the system is good as new. That hose on the radiator end was a major pain to remove though. Plastic on plastic with o-rings is never easy to separate. The thermostat side was easy because the connection is on a metal surface. Once I wrestled it out, installing the new one was simple. I did drive around without the underbody sheilds today so I could observe if there was any coolant leaking out. Everything was good except I noticed the temps were a little hotter than usual. I'm not sure if this is due to air in the system or because the shields were off. I bled the system when I got home and installed all new shields. We'll see if everything is back to normal tomorrow.

[Dumpspec]

hey, was wondering if you can point me out to the location of the idler pulley? thanks

[808MGuy]

Originally Posted by dumpm3

hey, was wondering if you can point me out to the location of the idler pulley? thanks

Sorry but I can't find a really good picture of it anywhere and I had this problem when I was researching to start this DIY. Once I ordered all the parts (with the help of a very helpful person at Tischer BMW) and they arrived, it was quite obvious which one was the idler pulley because it was the only one not attached to a mounting arm to tie in to the hydraulic tensioner.

[Dannys M3]

Deflection or Idler pulley shown. I have both adjusting pulleys with levers in case you need them. Sold the M3 so I don't need them.