Mitsubishi diesel engines - Measuring the Clearance between the Piston Pin and the Pin Boss; Measuring the Connecting Rod Bend and Twist

ENGINE MAIN PARTS - INSPECTION AND CORRECTION
2 - 28
3.4 Measuring the clearance between the
piston pin and the pin boss
Measure the piston pin diameter. Measure the
bore size of the piston pin boss. If the difference
between them exceeds the limit, replace with
new parts.
Unit: mm (in.)
Nominal
value
Standard
value
Limit
Piston pin
diameter
φ23
(0.9062)
22.944 to 23.000
(0.9039 to 0.9062)
―
Piston
pin-to-boss
clearance
―
0.006 to 0.018
(0.0002 to 0.0007)
0.050
(0.002)
3.5 Measuring the connecting rod bend and
twist
(1) Measure C and l as illustrated. If measured C is
more than 0.05 mm (0.0020 in.) per 100 mm
(3.937 in.) of measured l, correct the connecting
rod using a press.
Unit: mm (in.)
Standard value Limit
Connecting rod
bend and twist
0.05/100
(0.002/3.940)
or less
0.15/100
(0.006/3.940)
(2) Normally, a connecting rod aligner is used to
measure the connecting rod for bend and twist.
Note: Before measuring the connecting rod for bend,
tighten the connecting rod cap nuts to the
specified torque.
(3) When measuring connecting rod bend with the
piston installed to the connecting rod, place the
piston/rod assembly on a surface plate such that
the top of piston lies on the plate. Then, insert a
round rod with the same diameter as the crank pin
into the connecting rod large end. Using a dial
gauge, measure the top of the round rod for any
variation in height.
Measuring the piston pin-to-boss clearance
Measuring the connecting rod bend and twist
Using a connecting rod aligner to measure
the rod bend and twist
Using a dial gauge to measure
the connecting rod for bend
Measuring
location
Measuring
direction
A
B
C
D
Piston pin
C
C
C
100
0.05
C
100
0.05
Connecting rod twist
Connecting rod bend
l
l
l
l
Tightening torque
for connecting
rod cap nut
32.4 to 37.3 N
m
(3.3 to 3.8 kgf
m)
[23.9 to 27.5 lbf
ft]