Attention: If the toothed belt is removed, it must be replaced regardless of its service life. A BMW tool is required to adjust the correct tension.
Withdrawal
Remove the radiator fan.
Disconnect all spark plugs. To do this, you can use the HAZET 1849 tongs.
Remove cover 1 from ignition distributor. To do this, lift the upper and lower latches with a screwdriver.
Raise cable duct 2. To do this, insert a screwdriver into the slots -arrow-.
Unscrew the distributor cap (3 screws) and remove it together with the ignition wires.
Unscrew the slider of the ignition distributor 4 and remove it together with the cover 3.
Remove V-belt from alternator. To do this, unscrew bolt 1, unscrew the nuts of bolts 2 and 3. Turn bolt 3 in the direction of the arrow and thereby loosen the V-belt.
Loosen the water pump pulley. When doing this, compress the V-belt and thus prevent the pulley from turning.
See figure W - 10106
Unscrew vibration damper 1 from the crankshaft. At the same time, engage 1st gear, apply the handbrake, thus holding the belt pulley. Additional details shown in the figure:
- 1 Belt pulley
- 2 Bolt
- 3 Washer
- 4 Central bolt
- 5 Toothed belt pulley
- 6 Centering pin
- 7 Key
- 8 V-belt
Drain coolant.
See drawing W - 10176
Unscrew the housing of the thermostat of the cooling system under the distributor (3 bolts 10) and put aside. Remove thermostat 6 with gasket 7.
Unscrew 5 bolts 14 of lower toothed belt guard. Remove cover with gasket.
Loosen the 4 bolts of the top toothed belt guard. Do not lose the centering sleeves 16 for the top bolts.
Crank the engine to the top dead center of cylinder 1. The distributor pin on the camshaft sprocket must be at the bottom.
Lock the crankshaft at top dead center with an appropriate pin. To do this, insert the rod through the hole -arrow- in the engine block into the hole in the flywheel.
Loosen, without unscrewing, the bolt securing the camshaft pulley. This requires a special key.
See drawing W - 1059
Unscrew the nut of the tensioning roller 2, move the roller inward and thereby loosen the tension of the toothed belt.
Remove toothed belt.
Attention: After removing the toothed belt, if possible, do not bring down the position of the top dead center of the engine.
Installation
Attention: When applying a toothed belt, the position of neither the camshaft nor the intermediate shaft must be lost. Otherwise severe engine damage may occur or the engine will not develop full power. After tensioning the toothed belt, it is recommended to check the installation of the crankshaft and camshaft again.
Unscrew the cylinder head cover, remove the camshaft cover.
Check the position of the camshaft. At workshops, the camshaft is blocked with special tool 113 11 90. The camshaft is at top dead center when the cams of cylinder 4 intersect. The cams intersect if they point upwards symmetrically to the left and right with respect to the edge of the cylinder head of an obliquely mounted engine.
Slightly tighten the camshaft sprocket bolts with a tightening torque of 1-3 Nm. Turn the camshaft pulley in the direction of engine rotation as far as it will go so that the lug enters the groove.
Tighten the toothed belt tensioning roller nut slightly so that the tensioning roller can still move. 3
Place the toothed belt on the camshaft pulley and then on the tension roller, pulling the belt from the crankshaft pulley.
Attention: The toothed belt must be located on all pulleys in the middle.
Set the toothed belt tension gauge to "0".
Place a measuring device between the crankshaft and camshaft pulleys so that both outer rollers rest on the back of the toothed belt and the middle finger is between the belt teeth. See the operating instructions for the measuring device.
Move the tensioning pulley to the left with a hexagon socket wrench and thereby tension the toothed belt.
1 camshaft pulley
2 Tension roller
3 Bypass roller
4 Water pump
5 Oil pump
6 Oil pressure control valve
7 Timing gear housing cover
Specified value when using measuring device BMW 112080: 45-50 scale divisions.
Tighten the tension roller to 22 Nm.
Tighten the camshaft pulley to 60 + 5 Nm.
Attention: Remove the engine blocking rod, camshaft blocking tool and measuring device.
Crank the engine by the crankshaft pulley at least 2 turns (in the direction of rotation of the motor).
Again fix, as described above, the crankshaft and camshaft in the position of the top dead center.
Loosen the camshaft sprocket bolts again.
Install measuring device BMW 112080.
Loosen the fastening of the tension roller and briefly tension the toothed belt by 45-50 divisions of the instrument scale.
After that, set the tension roller to the final value of 32 + 2 scale divisions.
Tighten the tension roller to 22 Nm.
Tighten the camshaft pulley to 60 + 5 Nm.
Attention: Remove the engine blocking rod, camshaft blocking tool and measuring device.
After tensioning the toothed belt, it is recommended to check the position of the crankshaft and camshaft again.
Install the camshaft cover and cylinder head cover,
Screw on the upper toothed belt guard, paying attention to the position of the dowel sleeves.
Screw on the lower toothed belt cover, having previously checked the integrity of the gasket and, if required. replacing her.
Insert the thermostat into the housing, check the integrity of the sealing rings, replace if necessary.
Clean the contact surfaces, screw on the thermostat housing with a new gasket,
Fill with coolant, bleed air from the cooling system.
Place the vibration damper on the crankshaft, while aligning the hole of the damper exactly with the centering pin. Tighten vibration damper mounting to 23 Nm.
Fit and tighten the V-belt.
Tighten nuts and bolts 1-3 in figure W - 1056.
Install the camshaft sprocket cover, having previously checked the integrity of the cover sealing ring and, if necessary, replacing it.
Install the slider and distributor cap. Installation is carried out in the reverse order.
Insert the ignition wires into the guides.
Insert cable duct into cylinder head.
Put on the spark plug tips in the ignition sequence for cylinders 1-3-4-2.
Insert the fan shroud with the left and right strips into the bracket. Insert the spacer clips from the top left and right and fix them by driving in the plastic pins.
Install fan.
Attention: In the absence of adjusting and measuring devices (abroad, in case of an accident) temporarily tension the toothed belt so that the belt can bend 5-10 mm in the area between the camshaft toothed pulley and the tension roller. At the earliest opportunity, the belt tension should be done using a measuring device. Until then, avoid high engine speeds.