Removing and Installing Chain Tensioner

75 Screw plug
76 Sealing ring
76a Ball bearing
76b Ball
76c Ball cage
77 Compression spring
78 Snap ring
79 Thrust pin
83 Chain tensioner cage
84a O-ring
84b O-ring
a 74 mm
b Return hole
c Breather port

NOTE: The chain tensioner is always to be filled prior to installation.

Chain tensioners not giving satisfactory operation ought to be replaced complete.






A Chain tensioner with a gasket
B Chain tensioner with O-ring seal

There are two kinds of chain tensioners for these engines.

The O-ring version (B) must not be fitted with a gasket (version A).


Removal
1 Drain coolant.






2 On vehicles with air-conditioners, detach York A/C compressor together with bracket and connected lines. depositing on one side. However. first remember to remove fan and water pump pulley, additionally detaching air cleaner cover on engines with oil bath air cleaners. On engine 617.912 remove adapter at air cleaner (arrow).
3 Remove thermostat body.
4 Unscrew and remove chain tensioner.
5 Check O-rings for condition, replacing all that are damaged.


Installation
6 Fill chain tensioner. For this purpose hold tensioner at thrust pin and dip into SAE 10 engine oil beyond flange. Slowly press thrust pin right home 7 to 10 times. using press or drill press.

Once the chain tensioner is full, a good deal of force must be needed to compress the pin. Moreover, the pin must retract quite slowly and evenly.






7 Locate gasket or new O-rings (84a and 84b) on or in chain tensioner case (using new ones if necessary).
8 Apply chain tensioner and evenly tighten nuts and bolts.
9 Attach thermostat body with new gasket.
10 Fill with coolant.
11 Now proceed in reverse order of removal.
12 Run engine and check for leakage.