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Valve Mechanism
4---2
B. Changing camshaft/camshaft gear
1. Remove the inlet pipe between the turbocharger and the
induction manifold. Remove the valve cover and the breather
pipe. Remove the rocker arm mechanism.
2. Remove the radiator, cooling fan, alternator and the v---belt.
3. Remove the crankshaft nut. Remove the V---belt pulley in-
cluding the hub (on 620---engines the belt pulley must be re-
moved first).
4. Remove the timing gear casing cover (engine front cover).
24--- 6
5. Connect the pushrods in pairs, using o---rings or elastic
bands to prevent them from falling through.
Note!
Do not connect the pushrods too tightly as this might
cause them to bend or snap.
6. Crank the engine until the aligning marks on the idler gear
and camshaft gear are facing each other. Extract the cam-
shaft.
7. Separate the camshaft from the gear wheel using a press
or suitable drift.
8. Clean the parts which are to be refitted.
9. Fit the key in its groove. Heat the camshaft gear to
200
˚
C
in an oven and fit it on the shaft.
10. Lubricate bearing surfaces and lobes and insert the shaft
in the cylinder block. Ensure that the aligning marks on the
gears agree.
11. Fit the timing gear casing cover and the crankshaft V---belt
pulley and hub.
12. Free the pushrods and fit the rocker arm mechanism. Ad-
just the valves. Fit the valve cover and the breather pipe and
the inlet pipe between the turbocharger and the induction
manifold.
13. Fit the alternator. Fit the fan and the fan belt. Fit the radiator.
Modification of the cam shaft
From engine no L 13188 all 620/ 634--- engines are equipped
with a cam shaft where the front end bearing location has no
oil groove ( the bearing location is so called barrel shape).
30
˚
21--- 3/1
Note!
The new cam shaft is not fitting together with any previ-
ous bushing. The new bushing is recognised from the posi-
tion of the oil drilling which is not at the same place as the oil
drilling of the cylinder block,
30
˚
angle upwards from the hori-
zontal level.