X5 3.0 squeaking from belts when engine cold

[X5SND]

As for "what else" goes wrong in this area, everyone will have different answers. Some guys will tell you the water pump is common, but I'm currently sitting with about 178k-km on my original one; meanwhile I've had 2 OEM alternators fail. I'm not sure why the different tensioners, or what the difference is between them (aside from mechanical vs. hydraulic). The good news is that on the main belt there is only one tensioner and one idler pulley, both of which are inexpensive to replace.

Sometimes after changing a belt, if you don't clean the pulleys you can get some squealing....especially if moving between belt manufacturers and/or belts made of different materials.

When my idler started to go it would also squeal on startup for a second and only after parking for the night/extended period of time. Then eventually after about a week would stay there...sounded a bit like mice running around under the hood. Turned out the seal on the back if the bearing was shot.