Removing and Installing Tensioning Rail

Removal





Model 116.120

1 Remove radiator and fan.
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 pulley and vibration damper.
4 Rotate crankshaft with tool combination until recess in balancing disk is in front of bearing bolt of tensioning rail (Fig. step 12).






5 On engines with EGR (USA), remove pipe line between EGR valve and exhaust manifold (arrow). For this purpose, unscrew shielding plate (10).






6 On model 123 with level control, unscrew line holder on thermostat housing (arrow).






7 Unscrew closing plug of chain tensioner.

Attention!
The closing plug is under pressure of compression spring.






8 Remove compression spring in chain tensioner.






9 Mark camshaft sprocket and timing chain in relation to each other.










10 Remove slide rail in cylinder head.
Pull out bearing bolt by means of impact puller.






11 Remove camshaft sprocket.
For loosening necked-down screw, apply counterhold to camshaft sprocket by means of a screwdriver or steel bolt.






12 Knock out bearing bolt by means of impact puller.










Attention! If bearing bolt is stuck to the extent that it cannot be knocked out with impact puller, use puller part No. 115 589 20 33 00.
For this purpose, remove balancing disk and provide puller with a recess.
The recess is necessary to position the puller with cylinder crankcase cover installed.






13 Remove tensioning rail in upward direction.
14 Unscrew cyl. head screw M 8 in chain box adjacent to pressure bolt of chain tensioner by means of screwdriver (Allen wrench) with tommy handle.
15 Pull out pressure bolt of chain tensioner in inward direction (arrow).
16 Clean bearing bolt.
17 Renew badly worn tensioning rails and bearing bolts.


Installation
18 Coat bearing bolt on flange with sealing compound.
19 Position tensioning rail and knock in bearing bolt by means of impact puller.
20 Place camshaft sprocket with timing chain on camshaft, while paying attention to color marks.






21 Position necked-down screw for fastening camshaft sprocket and tighten to 80 Nm. For this purpose, apply counterhold to camshaft sprocket by means of a screwdriver or a steel bolt.






A Chain tensioner in assembly position
B Chain tensioner in operating position

22 Place pressure bolt of chain tensioner on assembly detent.






23 Insert compression spring.
24 Position closing plug of chain tensioner with new sealing ring and tighten to 90 Nm.
Make sure that pressure bolt is seated on thrust piece of tensioning rail.
25 Screw in cyl. head bolt M 8 by means of screwdriver (Allen wrench) with tommy handle.
26 For further installation proceed vice versa to removal.