Remove/Install Timing Chain Tensioner

Unfasten screw plug and remove hydraulic chain tensioner.


NOTE: The hydraulic chain tensioner can also be removed if the timing-case cover is removed.


NOTE: When replacing the unit, installation of the M44 hydraulic chain tensioner is also permissible.








Differentiating features:
The outer sleeves differ from one another. When extended, the groove is visible in version (1).
Hydraulic chain tensioner (1) can be dismantled (M42)
Hydraulic chain tensioner (2) cannot be dismantled (M44)


CAUTION! The procedure described below only applies to hydraulic chain tensioners which can be dismantled (1)







CAUTION! When the sealing screw is unfastened, the hydraulic piston extends and is locked by a detent ring to prevent it from compressing.
Without dismantling the hydraulic chain tensioner, it is not possible to press the hydraulic piston back down. Installation of the hydraulic chain tensioner in extended (locked) position leads to engine damage.







Installation:
The hydraulic chain tensioner must be dismantled and relocked in transport position (installation position).
Strike the outer sleeve of the hydraulic chain tensioner against a hard surface.
This releases the interlock and causes the hydraulic chain tensioner to jump apart.







Installation:
Arrangement of components:
(1) Outer sleeve
(2) Spring
(3) Hydraulic piston
(4) Detent ring
(5) Snap ring for locating in transport position (installation position)







Installation:
Secure hydraulic chain tensioner with protective jaws vise.
Insert detent ring (4) in groove of hydraulic piston.







Installation:
Compress hydraulic chain tensioner slowly and careful until detent ring (4) locates against slip taper on outer sleeve.
Press ends of detent ring (4) into slip taper of outer sleeve.







Installation:
Carefully and slowly compress hydraulic chain tension until snap ring (5) audibly locates in transport position (installation position).







CAUTION! If the detent point is exceeded, or not reached, the hydraulic piston is extended.
The hydraulic chain tensioner must be dismantled again and the procedure must be repeated.
Transport position (installation position):
X = (approx.) 68.5 mm







Installation:
Insert the hydraulic chain tensioner; replace the sealing ring of the drain plug.
Tighten the drain plug.
Tightening torque: [M22 x 1.5 screw] 40 Nm.







Installation:
The hydraulic chain tensioner must be unlocked.
Press tensioning rail briefly against the hydraulic chain tensioner, thereby unlocking the hydraulic piston which returns to its functional setting.
If necessary, when timing case cover is fitted, disengage by pressing briefly counter-engine wise.


NOTE: After disassembly, the hydraulic chain tensioner has no oil fill and must be operated for approx. 20 seconds at 3500 rpm with vehicle stationary to ensure functional safety.