2-Valve Cylinder Heads - Yanmar 3TNV82A-B Service Manual

Measuring and Adjusting Valve Clearance

2-Valve Cylinder Heads

1. Remove the valve cover. See Removal of Valve
Cover on page 6-52.
Note: If adjusting each cylinder individually, the
cylinder to be adjusted first does not
have to be the No. 1 cylinder. Select and
adjust the cylinder where the piston is
nearest to the top dead center after
turning, and make adjustment for other
cylinders in the order of firing by turning
the crankshaft.
2. Rotate the crankshaft clockwise as seen from
the coolant pump end, to bring No. 1 piston to
TDC on the compression stroke while watching
the rocker arm motion and timing grid on the
flywheel. (Position where both the intake and
exhaust valves are closed.)
3. Insert a feeler gauge (Figure 6-77, (1))
between the rocker arm and valve cap, and
record the measured valve clearance. (Use the
data for estimating the wear.)
Figure 6-77
4. If adjustment is required, proceed to the next
step.
5. Loosen the valve adjusting screw lock nut
(Figure 6-78, (1)) and valve adjusting screw
(Figure 6-78, (2)) on the rocker arm and check
the valve for inclination of the valve cap,
entrance of dirt, or wear.
TNV DI Service Manual
(1)
0001782A
(1)
Figure 6-78
6. Insert a feeler gauge of the correct thickness
(Figure 6-79, (1)) (see Adjustment
Specifications on page 6-6) between the rocker
arm and valve cap. Turn the valve adjustment
screw to adjust the valve clearance so there is a
slight "drag" on the feeler gauge when sliding it
between the rocker arm and the valve cap. Hold
the adjusting screw while tightening the valve
adjusting screw lock nut (Figure 6-78, (1)).
Recheck the clearance.
Note: There is a tendency for the clearance to
decrease slightly when the lock nut is
tightened. It is suggested that you make
the initial clearance adjustment slightly
on the "loose" side before tightening the
lock nut.
Figure 6-79
7. Apply oil to the contact surface between the
adjusting screw and push rod.
8. Rotate the crankshaft. Measure and adjust the
valves on the next cylinder. Continue until all
the valves have been measured and adjusted.
ENGINE
(2)
(1)
6-67