Mitsubishi diesel engines - Cylinder Head, Valve Mechanism

ENGINE MAIN PARTS - INSPECTION AND CORRECTION
2 - 18
1. Cylinder Head, Valve Mechanism
1.1 Measuring the cylinder head bottom face
distortion
Using a straight edge across the bottom face of
the cylinder head and a thickness gauge, measure
for any distortion. If the measured distortion
exceeds the limit, correct with a surface grinder.
Unit: mm (in.)
Standard value Limit
Cylinder head bottom
face distortion
0.05 less
(0.002 less)
0.10
(0.004)
1.2 Measuring the rocker arm bore and the
rocker shaft diameter
Measure the rocker arm bore and the rocker shaft
diameter to obtain the arm-to-shaft clearance. If
the clearance is between the standard value and
the limit, replace the rocker arm. If the clearance
is equal to or exceeds the limit, replace both the
rocker arm and shaft.
Unit: mm (in.)
Nominal
value
Standard value Limit
Rocker arm
inner
diameter
φ19
(0.749)
18.910 to 18.930
(0.7450 to 0.7458)
―
Rocker shaft
diameter
φ19
(0.749)
18.880 to 18.898
(0.7438 to 0.7445)
―
Arm-to-shaft
clearance
―
0.012 to 0.050
(0.0005 to 0.002)
0.200
(0.0079)
1.3 Measuring the valve spring for
squareness and free length
Measure the valve spring for squareness, free
length, etc. If any of the measured values
exceeds the limit, replace the spring.
Unit: mm (in.)
Standard value Limit
Free length 47 (1.85) 46 (1.81)
Squareness
θ=2.0º or less
△(gap)=0.2 (0.0079)
or less
Lf=47 (1.8504)
△=0.5
(0.0197)
across the
entire
length
Installed
length/load
mm (in.)/N
(kgf) [lbf]
39.0 (1.536)/
131 to 145
(13.3 to 14.7)
[29 to 33]
30.1 (1.185)/
279 to 309
(28.5 to 31.5)
[63 to 69]
-15%
Measuring the rocker arm inner diameter
and the rocker shaft diameter
Measuring the cylinder head bottom face
for distortion
θ
Measuring the spring for squareness
and free length
Measuring locations
and directions
Measuring
direction
Measuring
direction
Measuring
location
Free length
Spring squareness (gap)