Putting fan belt back onto the pulley for a 2002 bmw 525i sedan.

you need a cerpentine belt tool. check out all the pulleys and you will find that one has a square hole in the bracket holding the roller. that arm is spring loaded to maintain tension on the belt. Its not easy for the first time to do this job. The route the belt goes will be on a sticker diagram somewhere under the hood. sometimes they are on the under side of the hood, while sometimes they are on the car's grill frame. it is usually best to put the belt on all the pulleys except the alternator, then pull the tension pulley arm to facilitate the belt slipping onto the alternator pulley. Do not attempt to put it on the tension pulley last. and be careful the tension pulley tension can give you quite a severe pinch if you get your fingers caught under the belt.

2002 frontier 4 cyl: 1) take off air intake tube, 2 screws 13 mm above radiator. 2) 1st belt for power stirring has pulley, undo pulley screw and unscrew adjuster bolt enough to take belt off 3) 2nd belt for alternator and water pump has no pulley but adjusting bolt and mounting bolt on alternator pulley, loosen mounting bolt and unscrew adjusting bolt enough to take belt off, if alternator will not move go under the truck and remove plastic cover- 6 screws 13 mm heads, after that look directly under alt. Pulley and should see a screw head 9/16 in, loosen it so alternator can move, now should be easy to remove belt ( it will be a lot harder to put new one though) 4) 3rd belt for compressor has pulley so follow #2 to remove it ,have to be done under the truck. First 2 belts will have to work around fan blades to remove them so wear gloves. After replacing belts remember that not to over tighten bolt on pulleys.

The 5-61 is the 2007 525XI diagramThe 6-46 is the 2003 M5 diagram - I don't have a listing for the 2003 525I

Serpentine belt broke. A serpentine belt drive runs everything: power steering, ac, alternator (electrical power), and the water pump (explains the overheating). I'd bet anything that your belt broke.

It will only go on two ways. One way spins the alternator backwards. If you look at the fan on the alternator, you should be able to figure out which way it is supposed to spin.
Also, go to RealOEM.com and put in your body style (e46) and model. Browse Parts, choose Engine and then Belt Drive. You will see an image of the belts and pulleys that shows how it should look.

Hi and Welcome to Fixya

Here's how to replace the belt.

1
Disconnect the battery ground cable and lay it aside, ensuring that it does not touch metal. Unplug the wiring harness connector on the back of the alternator if so equipped. If you can't pry the plug tangs open with your fingers, use a screwdriver.
2
Remove the nuts on the back of the alternator with a wrench then pull the wires off the studs. Loosen the accessory drive belt tensioner with a socket, by pushing the tensioner towards the engine. Lift the belt off the pulleys.
3
Unbolt the alternator mounting bolts with the appropriate socket then remove the alternator.
4
Fit the new alternator onto its bracket then insert the mounting bolts. Tighten the right bolt to 18 foot-pounds of torque then tighten the left bolt to 37 foot-pounds of torque. Route the accessory drive belt around the pulleys, except for the tensioner pulley. The drive belt routing diagram is located on the fan shroud or the inside of the hood. Push the tensioner towards the engine. Slide the belt on the tensioner then release the tensioner.
5
Plug in the wiring harness connector if so equipped. Slide the wires onto the proper terminals on the back of the alternator. Tighten the battery feed wire nut to 71 inch-pounds of torque. Reinstall the negative battery cable.

Have a good one!

Focuses use an automatic belt tensioner which has no adjustment (as its spring loaded) if your belt is not tight enough replacement of the tensioner could be necessary..if you're asking due to a squealing problem check the pulley on the tensioner and the idler pulley..they are a common part to need changing

First check all pulleys for wobble or looseness. If all pulleys are OK, use the below diagram to put the belt on all pulleys except alternator. Put a wrench on tensioner pulley and pull down until the belt will slip onto the alternator pulley. Check that belt is still on all pulleys before starting. If belt comes off again, one of the components is failing (usually an idler, tensioner or water pump wobbling).

Hello, first of all disconet your battery. Then locate your alternator and remove the wiring. You will then see two bolts, one is for your fan belt adjustment, take this bolt out and dont loose it. The second bolt is much longer, this is the bolt that allows you to move your alternator back and forth so that you can tighten your fan belt. Remove this and as you pull it out hold onto yoour alternator as it will now come out. You then position new alternator sliding long bolt back in place. Do it up but not tightly at this point. Replace the smaller bolt and make sure that you put your fan belt back on. Pull the alternator tighly onto the fan belt before tightening the smaller bolt. Once the fan belt is tight you can then tighten the long bolt. Reconct your wiring, reconect you battery and you should be right to go. If theres a squealing sound when you start the car you may have to retighten your fan belt, you dont need to take any wiring off to do this. I hope this is helpfull.

An image of a serpentine belt, hope this will help you,
Eitan.