11 31 051 Replacing timing chain (S55 engine)
Special tools required:
- 11 0 300
- 11 4 280
- 11 8 180
- 11 8 660
- 11 9 260
- 11 4 480
Attention!
After each release of the central bolt on the crankshaft, the following components must be replaced without fail.
- Central bolt
- EKA grip disc
- Camshaft sprocket with the welded-on EKA grip discs
- Camshaft sprocket for the timing chain drive
Necessary preliminary work:
- Remove CYLINDER HEAD COVER .
- Remove all SPARK PLUGS .
- Remove CRANKSHAFT SEAL at front.
- Remove TENSIONING DEVICE for drive belt.
- Remove VIBRATION DAMPER .
- Check TIMING .
- Remove the SEALING CAP for the vacuum pump.
- Remove SEALING CAP for chain tensioner oil pump
- Remove the CHAIN MODULE of the oil vacuum pump.
Engine removed:
Block crankshaft with special tool 11 9 260.
Attention!
To release central bolt (1), remove special tool 11 0 300.
Vehicles with transmission installed:
Attach special tool 11 8 180 to manual transmission with existing transmission bolts (1).
Block crankshaft in direction of arrow with special tool.
Attention!
Before releasing the central bolt, the hydraulic chain tensioner must be drained.
Carefully press tensioning rail (1) with a suitable screwdriver (2) in direction of arrow.
As the oil pressure in the chain tensioner can only be drained pulsating, the tensioning rail (1) must be pressed several times.
Secure tensioning rail with a suitable lock pin with a diameter of 2.5 to 3 mm.
Attention!
Break-away torque of central bolt > 600 Nm.
A 3/4-inch tool (large powered square) is required to release central bolt.
Release central bolt (1) with 3/4-inch tool (2).
Screw in vibration absorber screws (1).
Move hub (2) on crankshaft forward in direction of arrow to remove.
Open screw plug (1).
Tightening torque: 11 31 8AZ .
Open screw plug (1).
Tightening torque: 11 11 7AZ .
Installation note:
Replace aluminium screws .
Release bearing journal (1) from timing chain module on cylinder head.
Tightening torque: 11 31 6AZ .
Attention!
Install special tool 11 4 280 to release the central bolts on the intake and exhaust camshaft adjusters.
Release central bolt (1).
Release central bolt (1).
Set down central bolt (1) and pulse sensor wheel (2) of the intake camshaft on special tool 11 4 480 in neat order.
Set down central bolt (1) and pulse sensor wheel (2) of the exhaust camshaft on special tool 11 4 480 in neat order.
Release chain tensioner (1) and remove.
Raise timing chain (1) and remove exhaust camshaft adjuster (2) in direction of arrow.
Raise timing chain (1) and remove intake adjuster (2) in direction of arrow.
Release bearing journal (1) from timing chain module on crankcase.
Tightening torque: 11 31 5AZ .
Release bolts (1) from timing chain module on cylinder head.
Tightening torque: 11 31 4AZ .
Remove chain module with timing chain and camshaft sprocket upwards in direction of arrow.
Installation:
Attention!
Note installation direction of sprocket (2).
Collar (see arrow in illustration) on sprocket (2) points to engine .
Incorrect assembly will result in engine damage .
Pull timing chain (1) upwards until camshaft sprocket (2) engages chain guide (3).
Install timing chain (1) and sprocket (2) in this position.
Installation note:
Always hold timing chain (1) under tension.
Timing chain (1) may jam on chain guide (3).
Push on friction plate (1) without retainers.
Attention!
The S55 engine requires special friction plates between the friction surfaces.
The engine will incur damage if the friction plates are damaged or are not fitted.
Position module (1) for oil pump drive.
Position module (2) for camshaft drive.
Insert hub (3) for vibration absorber with grip disc.
Insert central bolt (1) with hub for crankshaft.
Tighten down central bolt (1).
Tightening torque: 11 21 1AZ .
Install INTAKE AND EXHAUST CAMSHAFT ADJUSTERS .
Crank engine twice.
Check TIMING .
Replace front CRANKSHAFT SEAL .
Assemble engine.