Removal, installation and adjusting the tension of the camshaft drive belt (BMW 3 Series E21)

Removal

Drain the engine cooling system and disconnect the cooling system hoses from the thermostat housing.

Loosen the generator drive belt tension bar mounting bolt.

Remove the crankshaft pulley and alternator drive belt, then remove the TDC sensor.

Remove the vibration damper from the hub.

Remove the timing belt cover.

Remove the spark plugs from the cylinder head and turn the crankshaft to the position corresponding to the TDC of the end of the compression stroke of the piston of the 1st cylinder. In this case, the arrow on the toothed pulley of the camshaft should align with the mark on the cylinder head, the mark on the hub of the torsional vibration damper should coincide with the mark on the front cover of the cylinder block, and the mark on the housing of the ignition distributor sensor should be opposite the middle of the speed limiter.

Mark the direction of rotation of the toothed belt with chalk.

Loosen the tension roller mounting bolts and move it toward the engine, then tighten the upper mounting bolt.



Remove the timing belt.

Warning: After removing the timing belt, do not turn the engine crankshaft.

Installation

Check the condition of the timing belt and replace it if necessary.

Make sure that the arrow on the camshaft toothed pulley matches the mark on the cylinder head, the marks on the vibration damper hub and on the front cylinder block cover, and the mark on the ignition distributor sensor housing matches the center of the speed limiter.

Place the timing belt on the pulleys in the direction opposite to the direction of rotation of the crankshaft, first of all it is necessary to place it on the crankshaft pulley.

Loosen the upper tension roller mounting bolt and use a ratchet wrench to turn the crankshaft by the camshaft pulley one or two turns in the direction opposite to its rotation to tension the timing belt.

Tighten the upper and lower tensioner pulley mounting bolts and again check that the timing marks are aligned.

Install the timing belt cover while securing the lifting arms.

Install the torsional vibration damper on the hub, ensuring that the mounting pin is in the correct position.

Install the TDC sensor, while maintaining a gap of 0.2-2.0 mm between it and the torsional vibration damper.

Install the crankshaft pulley, put on the alternator drive belt and adjust its tension.

Connect the cooling system hoses to the thermostat housing, fill with coolant and remove air locks from the cooling system.