Yaroslavl Engine Plant YMZ-536 Operation Manual page 137

6. Check or adjust the valve clearance.
7. To adjust the clearance, do the following (see Fig. 46):
 release the lock nut 3 of the adjusting screw 2 of the intake or
exhaust valve rocker arm 1;
 insert a feeler gauge of the required thickness between the
rocker arm cup 5 and the yoke 4;
 turn the adjusting screw 2 until the rocker arm cup 5 touches
the feeler gauge;
 holding the screw against rotation, tighten lock nut 3;
 check the clearance by means of feeler gauges whose thickness
corresponds to the clearance limit values
If the clearances are adjusted properly, a feeler gauge of the same
thickness as the lower limit of the clearance value must enter freely,
and a feeler gauge with the thickness corresponding to the upper
clearance limit value must enter with some force applied.
During further crankshaft turning, an up to 0.05 mm deviation from
the valve clearance limit values due to a possible runout of the valve
train mating parts is considered to be acceptable.
8. Further valve clearance adjustment must be performed according
to the firing order, i.e. in cylinders 5, 3, 6, 2 and 4 respectively;
each time the crankshaft must be turned clockwise (if looking from
the fan side) to 120 degrees.
9. Remove the crankshaft turning gear and install the plugs 2 and 3
into the holes on the flywheel housing.
10. Start the engine and listen to the sound. If the clearances are
adjusted properly, the valve train will not knock. In case of a
characteristic knocking sound, stop the engine and readjust the
clearances.
11. Install the cylinder head cover and fix it with bolts.
12. Connect the crankcase gas discharge hose pipe.
137