Engines M20, M21, M30, M40 (2-valve engines except 525td/tds)
See end of section for instructions on the M50 engine.
Withdrawal
Remove fan.
Unscrew bolt 1, unscrew nuts of bolts 2 and 3. Turn bolt 3 in the direction of the arrow to loosen the V-belt.
Loosen the power steering pump V-belt in the same way. Then remove the alternator V-belt.
Installation
Check the V-belt before installation. If the edges are frayed, cracked or torn, the V-belt must be replaced.
Fit and tighten the V-belt.
V-belt tension
- Tighten tensioning roller 2 with a torque wrench to a tightening torque of 7 Nm.
- Tighten bolt nut 3.
In workshops, the exact check and adjustment of the V-belt tension is carried out using a special machine.
The tension hook 2 of the device must be placed in the middle of the teeth. In this case, the pointer arrow should be in the green or yellow sector of the scale for the corresponding engine. In addition, the set value on the scale is different for a new and a used belt. If the pointer is not in the specified sector of the scale, adjust the tension of the V-belt.
If such a device is not available, the belt should be tensioned so that it bends when pressed with a finger in the middle between the pulleys by 5 mm. The V-belt tension must then be adjusted as soon as possible using the BMW tool.
Tighten bolt 1 and nut 2.
Fit and tension the V-belt of the power steering pump.
Install fan.
M50 engine (520i, 525i since May 1990)
The 4-valve engine has a wider ribbed V-belt driving the alternator, water pump and power steering pump. With the appropriate composition of the equipment, the air conditioning compressor is driven by a second ribbed V-belt.
Withdrawal
If equipped, remove the A/C compressor V-belt as described below.
Place the wrench head on the idler pulley bolt. Turning it slowly clockwise compresses hydraulic tensioner 1. Remove ribbed V-belt.
Installation
Fit a new V-ribbed belt according to the diagram shown, while moving the tensioning roller all the way to the right, just as when removing. Pay attention to the correct position of the grooves on the belt pulleys.
Unload the tension roller. Tension is generated by a hydraulic tensioner and is not adjustable.
M51 engine (525td/tds)
The 2.5L diesel engine has a wider ribbed V-belt driving the alternator, water pump and power steering pump.
Attach a powerful screwdriver or similar lever to the tensioning element, see illustration. Compress the belt tensioner and remove the V-ribbed belt.
Fit a new V-ribbed belt according to the diagram shown, while moving the tensioning roller all the way to the right, just as when removing. Pay attention to the correct position of the grooves on the belt pulleys.
Unload the tension roller. Tension is generated by a hydraulic tensioner and is not adjustable.
If removed, install the engine compartment pan.
Lower the car.