Timing Belt: Service and Repair

Toothed Belt

Special tools, testers and auxiliary items required

• Toothed Belt Tensioner (T10020)

• Locking Tool (T40098)

Removing

- Remove engine cover - arrows -.





CAUTION!
Cover cap of expansion tank with rag and open carefully, as hot steam or hot coolant may escape when opening.

- Open cap of coolant expansion tank.

- For vehicles with auxiliary heater, remove bolts - arrows - for exhaust pipe of parking heater/auxiliary heater on noise insulation.





- Loosen quick-release fasteners - 1 - and - 2 - and remove front noise insulation.





- Drain engine coolant. Refer to => [ Cooling System, Draining and Filling ] Procedures

- Bring lock carrier into service position. Refer to => [ Lock Carrier, Moving into Service Position ] Lock Carrier, Moving Into Service Position.

- Disconnect coolant pipe - arrow -.





• Before removing ribbed belt, mark the turning direction on it with chalk or a felt tip pen. A reversed turning direction can cause damage to the belt under operating conditions.

- Mark direction of rotation of ribbed belt.

- Pivot belt tensioner for ribbed belt in direction of - arrow - to relieve tension on ribbed belt.





- Secure tensioning element using Locking Tool ( T40098).

- Remove ribbed belt.

- Bring camshaft gear to marking for TDC cylinder 1 by turning crankshaft. Marking on camshaft gear must align with arrow on toothed belt guard.





- Remove vibration damper/belt pulley.





- Remove bolts from lower toothed belt cover - arrows -.





- Remove remaining bolts from toothed belt guard - arrows - and remove toothed belt guard from engine.





- Mark rotational direction of toothed belt.

- Loosen tensioning roller and remove toothed belt.

- Then, turn crankshaft back slightly.

Installing

• When turning camshaft, crankshaft must not be at TDC. Valves and/or pistons may be damaged.

• The engine must be no more than warm to touch.

- Place toothed belt onto crankshaft sprocket (observe direction of rotation).

- Secure lower toothed belt cover with two lower bolts.

- Install vibration damper/belt pulley with new bolts.

- Set crankshaft and camshaft to TDC at cylinder 1 - arrows -.





- Route toothed belt in sequence: Tensioning roller, camshaft gear, coolant pump and last over relay pulley - arrow -.





• Be sure tensioning roller is properly seated in cylinder head.





- Tension toothed belt. Do this by turning hex key at eccentric toward right (in direction of - arrow -) until notch is positioned above tab.





- Release tension on toothed belt again.

- Now tension toothed belt until notch and tab align.

- Tighten tensioning roller nut.

- Turn crankshaft 2 revolutions further in direction of engine rotation until engine is positioned at TDC again. For this it is necessary that the last 45° (1/8 rotation) is turned without interruption.

- Check tension of toothed belt again. Specified value: Tab and notch align.

- Check valve timing again.





If markings do not match:

- Repeat valve timing adjustment.

If markings match:

- Install toothed belt guard - arrows -.





- Install crankshaft belt pulley. Refer to => [ Crankshaft Pulley ] Crankshaft Pulley.

- Install ribbed belt. Refer to => [ Ribbed Belt ] Ribbed Belt.

- Fill with coolant. Refer to => [ Cooling System, Draining and Filling ] Procedures.

- Install lock carrier with attachments. Refer to =>
Radiator Support Radiator Support

- Place torque support stop onto rubber buffer for torque support under its own weight and tighten nuts - arrows -.





- Install front bumper cover.

- Check headlight adjustment.

- Install noise insulation pan.

- Install engine cover.

Tightening Specifications