Timing Chain: Service and Repair

Renewal





Model 116.120

1 Unscrew pencil element glow plugs.
2 Disconnect regulating linkage to remove cylinder head cover. Pull out locking eye of longitudinal regulating shaft (arrow).






Model 123

On models 116.120 and 123, pull longitudinal regulating shaft out of rubber mount in forward direction and remove in rearward direction.






Model 126.120

On model 126.120, pull longitudinal regulating shaft out of guide lever in rearward direction and remove in forward direction.

On models 123 with automatic transmission 722.303 (W 4 A 040) and 126.120, pull off central plug for vacuum lines (71) or vacuum lines. Disconnect Bowden wire, compress black plastic clip (arrow) and pull Bowden wire out of holder in rearward direction.

3 Remove chain tensioner. Service and Repair
4 Cover chain box with a rag and grind off both chain bolts on one link of timing chain. First secure chain ends with a wire on camshaft sprocket.
5 Connect new timing chain with a plug link to old timing chain, while simultaneously pushing out open link (Fig. step 7). Remove safety wire.






6 Turn crankshaft with tool combination slowly in direction of rotation of engine, while simultaneously pulling up the old timing chain until the connecting link comes to rest at uppermost position of camshaft sprocket.

Attention! Timing chain should be in mesh with camshaft and crankshaft sprocket during rotation.










7 Disconnect old timing chain and connect the ends of the new timing chain with a plug link.

For this purpose, secure chain ends with wire to camshaft sprocket.

Insert plug link into chain from the rear (arrow).

8 Insert loosely enclosed outer plate of plug link (with punched-in IWIS identification) into press-on tool (arrow). The outer plate is magnetically held in place. Remove wire.






9 Place press-on tool on plug link and press on plate up to stop. For this purpose, hold press-on tool in place on vertical lever.






10 Position die (02) of assembly tool in such a manner that the notch (arrow) is facing forward.






11 Hold assembly tool on handle and rivet chain bolts individually.

[Tightening torque of spindle approx. 30-35 Nm (reference value)]






12 Check chain bolt rivet and rivet again, if required (arrows).






13 Rotate crankshaft and check adjusting marks at TDC position of engine.

Note: If the adjusting marks are not in alignment, check timing of camshaft and start of delivery of injection pump. Adjustments

14 Install chain tensioner.
15 Screw in glow plugs with box wrench 20.8 mm and connect.
16 Mount cylinder head cover.