bmwrepairs: How to remove Accessory Drive Belt on 2005 BMW 325 ?

Adjustment

Alternator Belt

On serpentine belt equipped engines, belt tension is automatically adjusted by the tensioner idler. If not equipped with a single serpentine belt, the fan belt tension is adjusted by moving the alternator on the slack adjuster bracket. The belt tension is adjusted to a deflection of approximately ¹ / ₂ in. under moderate thumb pressure in the middle of its longest span. On many engines, the position of the top of the alternator is adjusted via a bolt that is geared to the bracket. This bolt is turned to position the alternator and determine tension and then is locked in position with a lock bolt.

Multi-Ribbed V-Belts

If installed, remove the protective dust cap from the front of the tensioner roller.

Loosen the pivot bolt on the tensioner roller.

Insert a hex wrench into the tensioner roller, turning counterclockwise to increase tension and clockwise to reduce tension.

When the desired tension is achieved, tighten the tensioner roller pivot bolt.

Fig. The tensioning rollers have dust covers that are removed when adjusting or replacing the belts

Fig. The multi-ribbed V-belt is adjusted by loosening the 1) pivot bolt and rotating the tensioning roller with the 2) hex shaped tensioning socket

Fig. View of the 10mm adjustment hex, which is shown by the mirror, in the tensioner roller body

Fig. With the dust cover removed, insert a 10mm hex tool into the tensioner body, then . . .

Fig. . . . loosen the lock bolt, adjust the tension with the hex tool and retighten the lock bolt

Power Steering Pump

Tighten the drive belt so when pressure is applied to the belt, the distance between both belt pulleys is 0.2-0.4 in. (5-10mm) of deflection.

Disconnect the negative battery cable. Loosen the nuts on the adjusting pinion.

Tighten the belt to the recommended specification and tighten the adjusting pinion nuts.

Connect the negative battery cable.

Serpentine Belt

The serpentine belt is tensioned by a spring loaded tensioner assembly. No adjustment is possible.

V-Belts

Loosen the locknut for the slotted adjustment bracket and the pivoting fasteners.

Move the component to achieve the desired belt tension. If equipped with a geared tensioner roller, use the roller to achieve the proper belt tension.

Tighten the slotted adjustment locknut, then the pivoting fasteners.

Fig. To adjust a typical V-belt, loosen the locknut (1) while holding the adjustment bolt (2), and turn the geared tensioner roller (3) to the desired tension, then tighten the locknut

Inspection

There are three basic types of accessory drive belts used on the BMW 3 Series and Z3 models: the V- belt, flat multi-ribbed V-belt and serpentine belt. The cross-section of a V-belt looks much like a V, hence its name. The contact surface of the belt is the two beveled sides, the inside surface is flat and narrow and the outside surface flat and much wider. The V-belt is most often tensioned by a component that is allowed to pivot, however at times an idler tensioner or a shimmed pulley can be used.

The flat multi-ribbed V-belt actually resembles a serpentine belt, however, unlike a serpentine belt, only the ribbed inner surface of the belt makes contact with the components' pulleys. The back of a multi-ribbed belt may ride against an idler or tensioner pulley.

Multi-ribbed V-belts typically operate one or two accessories per belt, whereas a single serpentine belt can often times drive multiple the accessories. The flat multi-ribbed V-belts used on BMW models require periodic inspection and adjustment because the belts wear with age and are under tension and stretch over time. The serpentine belt is tensioned by a spring loaded tensioner assembly that keeps a constant tension on the belt at all times. As a serpentine belt wears and stretches over time, within a specified range, the tensioner automatically compensates for the wear and belt stretch.

Inspect the belts for signs of glazing or cracking. A glazed belt will be perfectly smooth from slippage, while a good belt will have a slight texture of fabric visible. Cracks will usually start at the inner edge of the belt and run outward. All worn or damaged drive belts should be replaced immediately. It is best to replace all drive belts at one time, as a preventive maintenance measure, during this service operation.

Fig. There are typically 3 types of accessory drive belts found on vehicles today

Fig. An example of a healthy drive belt

Fig. Deep cracks in this belt will cause flex, building up heat that will eventually lead to belt failure

Fig. The cover of this belt is worn, exposing the critical reinforcing cords to excessive wear

Fig. Installing too wide a belt can result in serious belt wear and/or breakage

Belts should be inspected for both tension and condition at intervals of one year or 12,500 miles (20,000 km), and if manually tensioned, the adjustment should be rechecked shortly after replacement. On manually adjusted belts, tension is checked by applying pressure (about 10-15 lbs.) with your thumb midway between 2 pulleys. The belt should deflect (stretch) about ¹ / ₂ - ³ / ₄ in. (12-19mm) for each 10 inches (250mm) of distance between pulley centers. The belt should spring tight, not sag or have play, but not so tight that it requires tremendous effort to get a slight deflection. Excessive belt tension may wear the bearings of the accessory being driven, or may stretch and crack the belt. Insufficient tension will cause belt slippage and glazing.

Inspect the belt for separation between the outer surface and the V, and for radial cracks, which usually begin at the inner surface. The driving surfaces should be rough, slightly cross-hatched because they are fabric covered. If the surface is perfectly smooth, the belt has slipped, and this has caused overheating. A glazed belt cannot offer a sufficient amount of friction to carry the load without excessive tension. Belts which show cracks or glazing should be replaced.

Inspect the drive belt for signs of glazing or cracking. A glazed belt will be perfectly smooth from slippage, while a good belt will have a slight texture of fabric visible. Cracks will usually start at the inner edge of the belt and run outward. All worn or damaged drive belts should be replaced immediately.

Removal & Installation

NOTE

Sometimes a drive belt must be removed to gain access to perform other repairs. Always mark the direction of rotation of any belt that is to be removed. This will help to prolong the belt's service life.

E46 Models
A/C Drive Belt

Before servicing the vehicle, refer to the Precautions section.

If necessary, remove splash guard.

Models with hydraulic drive belt and tension jack: Remove the dust cab. Push back belt tensioner at bolt connection of guide pulley and remove drive belt.

Model with mechanical drive belt and tension jack: Press back drive belt tensioner at hexagon head or Torx socket and remove drive belt.

To install, reverse removal procedure.

Alternator Drive Belt

Before servicing the vehicle, refer to the Precautions section.

Remove fan clutch with fan impeller.

Remove A/C compressor drive belt.

Remove cap from tensioning roller.

Relieve tension on belt drive. Remove drive belt.

To install, reverse removal procedure.

E65 Models
A/C Drive Belt

Before servicing the vehicle, refer to the Precautions section.

Remove alternator drive belt.

Remove engine splash guard.

Pretension belt tensioner slowly and carefully with a Torx socket as far as it will go and secure with special tool 11 3 340. Remove drive belt.

To install, reverse removal procedure.

Alternator Drive Belt

Before servicing the vehicle, refer to the Precautions section.

Remove fan clutch with fan impeller.

Pretension belt tensioner slowly and carefully with a Torx socket as far as it will go and secure with special tool 11 3 340. Remove drive belt.

To install, reverse removal procedure.

E85 Models

Before servicing the vehicle, refer to the Precautions section.

Remove fan cowl.

Turn belt tensioner clockwise until bore is flush on housing. Hold belt tensioner under tension.

Secure belt tensioner with special tool 11 3 340.

Remove drive belt towards top.

To install, reverse removal procedure.

Multi-Ribbed V-Belts

Before removing the belt, take note of the routing of the belt over the pulleys. If there is not a diagram on an underhood sticker, draw a diagram of the routing.

If installed, remove the protective dust cap from the front of the tensioner roller.

Loosen the pivot bolt on the tensioner roller.

Rotate the pulley clockwise to release the tension in the belt. If additional movement is needed, remove the tensioner roller.

Remove the belt from the pulleys.

To install:

When replacing the belt, be sure that the belt is fully seated in the grooves and that it is properly routed.

Insert a hex wrench into the tensioner roller turning counterclockwise to increase tension and clockwise to reduce tension.

When the desired tension is achieved, tighten the tensioner roller pivot bolt.

Serpentine Belt

WARNING

Some BMW models use an automatic hydraulic belt tensioner that is filled with oil. If this tensioner is removed it must be stored upright. If improperly stored, bleed the tensioner by compressing it in an upright position several times.

When replacing a serpentine belt make sure to use an exact fitting replacement belt, as the belt tension is provided by a spring loaded tensioner assembly. A belt that is too long will have insufficient tension. A belt that is too short will have excessive belt tension.

NOTE

If the serpentine belt is not being replaced, make sure to mark the belt's direction of rotation before removing. Reinstall the belt in the same direction from which is was removed.

If installed, remove the protective dust cap from the front of the tensioner roller.

Move the self tensioning to release the tension on the drive belt. On M44 engines, if necessary, lock the tensioner retracted by installing a ³ / ₁₆ inch drill bit or 4mm hex tool through the eyelet of the tensioner body and its mounting bracket to keep the tensioner retracted.

Remove the belt from the pulleys.

To install:

Properly route the belt around the tensioner roller and all but one of the pulleys, making sure the belt is fully seated in the pulley grooves and properly routed.

If installed, move the automatic tensioner enough to remove holding tool used to keep the tensioner retracted.

Keep the automatic tensioner fully retracted while applying a slight load to the belt to keep in place and move the belt over the remaining pulley.

Slowly and carefully release the tensioner assembly to apply tension to the belt.

Verify the belt is properly routed and fully seated before starting the engine.

Fig. The automatic belt tensioner is moved to release the belt tension allowing the belt to be removed-M44 engine shown

Fig. Serpentine belt routing on the M44 engine

Fig. The tensioner on M44 engines can be held in the retracted position by inserting a suitable drill bit or hex tool through the holes in the tensioner and bracket

Fig. Belt routing on the E36 series 325i with the M50 engine

Fig. Removing tension from the belt tensioner roller

Fig. On E36 model 6-cylinder engines, remove the tensioner cover to access the tensioner mounting bolt

Fig. On E36 model 6-cylinder engines, the tensioner mounting bolt is used to release the tension on the serpentine belt

Air Conditioner Belts

On versions with a hydraulic belt tensioner:
1. Remove the dust cover from the center of the tensioning roller.
2. Insert a suitable tool on the tensioning roller mounting bolt and press in a clockwise motion to relieve the belt tension.

On versions with a spring loaded mechanical tensioner:
1. Locate the protruding hex on the tensioner housing.
2. Install a suitable tool onto the provided hex head and rotate the tensioner assembly to relieve the belt tension.

While relieving the belt tension, remove the air conditioner drive belt.

On versions with a pivoting tensioner roller:
1. Remove the tensioner dust cover.
2. Insert a 10mm hex tool into the body of the tensioner, then loosen the pivot bolt.
3. Rotate the tensioner clockwise to relieve the belt tension.

While relieving the belt tension, remove the air conditioner drive belt.

Installation is the reverse of the removal procedure.

V-Belts

Fig. Always note a belt's direction of rotation before removal if the belt is to be reinstalled

Replace belts with the proper part. Make sure the belt is not only the correct length, but also the correct inner and outer width. A belt that is too short will put an excessive load on the component and potentially internally damage its bearings. A belt that is too long will slip causing premature belt wear and heat from the slippage.

Replace the multiple belts in sets only, as work belts stretch and mixing stretched belts with new ones will prevent even distribution of the load.

NOTE

Do not attempt to change belt tension or rotate an accessory for belt replacement without loosening both the adjustment bolt (the bolt which runs in a slotted bracket) and the pivot bolt.

Many components come equipped with toothed bolt adjusters that prevent having to pry on the component to tension the belt. If the component is not equipped with a toothed bolt adjuster, don't pry the component with a prytool. You should be able to get sufficient belt tension by hand. This applies especially to components with aluminum castings or air/fluid pumps, where distortion of the housing can be a catastrophic problem. If you must pry, make sure the adjustment fasteners are loose and protect the component by placing a small block of wood between the component and the prytool. Pry as close to the pulley as possible, to avoid distorting the housing of the component. Some accessory mounting brackets are designed with a slot or square hole into which you can insert a socket drive for tensioning purposes.

To replace a belt, first locate the pivot bolt. This holds the unit to the engine block or to a short bracket which has only a hole-no slot. If the pivot bolt does not use a nut welded onto the back of the accessory or a bracket you will have to apply wrenches at both ends; to both the bolt and nut, to loosen this bolt. Loosen the bolt slightly-don't release all tension, as you will want the accessory to stay securely mounted to get an accurate tension adjustment later.

Fig. Location of the adjuster bolt on the alternator-E36 318i shown

Loosen the adjusting bolt locknut.

Move the component toward the engine to release the belt tension. If additional movement is needed, it may be necessary to remove the adjustment bolt entirely.

Remove the belt.

To install:

Position the belt around all the pulleys. Make sure it is fully seated into all the pulley grooves.

Tighten the tensioner lock nut slightly, but not enough that the component cannot be moved.

Move the component as necessary to achieve the correct belt tension, then tighten the adjustment locknut.

NOTE

When installing a new belt (one run less than 10 minutes), start the engine and allow to idle for 10 minutes, then recheck the belt tension and adjust as necessary.

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