Adjustment Of Valve Clearance - Yanmar 4LHA-HTP Operation Manual

Chapter 2 Basic Engine
4. Cylinder Head
(1) Rocker arm shaft and rocker arm bushing
Measure the outer diameter of the shaft and the inner
diameter of the bushing, and replace if wear exceeds the
limit.
Intake and exhaust
valve rocker arm
shaft outside dia.
Intake and exhaust
valve rocker arm bush-
ing inside dia.(assembled)
Valve rocker arm shaft
and bushing clearance
at assembly
Replace the rocker arm shaft bushing if it moves and replace
the entire rocker arm if there is no tightening shrinkage.
(2) Rocker arm spring
Check the rocker arm spring and replace it if it is corroded
or wom.
(3) Rocker arm and valve top cap wear
Inspect the contact surface of the rocker arm and replace it
if there is abnormal wear of flaking.
(4) Inspect the contact surface of the valve clearance
adjustment screw and push rod and replace if there is
abnormal wear or flaking.

4-8 Adjustment of valve clearance

(1) Make adjustments when the engine is cool.
4LHA-STE/-STZE
4LHA-STP/-STZP
0.1
Intake
0.5
Exhaust
mm(in.)
Wear limit
Standard
18.459-18.479 18.35
(0.7224)
(0.7267 - 0.7275)
18.60
18.50-18.52
(0.7323)
(0.7283 - 0.7291)
0.021 - 0.061
(0.0008 - 0.0024)
4LHA-HTE/-HTZE
4LHA-DTE/-DI Zh
4LHA-HTP/-HTZP
4LHA-DTP/-DTZP
0.1
0.1
0.3
0.4
(2) Be sure to adjust the opening and closing angles for
both the'intake and exhaust valves when reassem-
bling the timing gear.
b.TDC
a.BDC
Intake valve open
Intake valve closed
Exhaust valve open
Exhaust valve closed
2-20
4LHA Series
t
Adjusting
screw
Lock nut
T.D.C.
a.TDC
b.BDC
B . D C .
4LHA
4LHA-HTE/
- S T E / S T Z E
-HTZE
- S T P / S T Z P
-HTP/
-DTE/DTZE
-HTZP
-DTP/DTZP
5 9 ± 5
5 9 ± 5
b.TDC -
6 3 ± 5
6 3 ± 5
a.BDC
-
5 8 ± 5
51 ± 5 "
b.BDC
4 6 ± 5
3 9 ± 5 -
a.TDC
Deg.