Measuring The Clearance Between The Piston Pin And The Pin Boss; Measuring The Connecting Rod Bend And Twist - Mitsubishi diesel engines Service Manual

ENGINE MAIN PARTS - INSPECTION AND CORRECTION
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.
Nominal
value
Piston pin ƒ Ó 23
diameter
(0.9062)
Piston
pin-to-boss
• \
clearance
3.5 Measuring the connecting rod bend and
twist
Measure C and l as illustrated. If measured C is
(1)
more than 0.05 mm (0.0020 in.) per 100 mm
(3.937 in.) of measured l, correct the connecting
rod using a press.
Standard value
0.05/100
Connecting rod
(0.002/3.940)
bend and twist
(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.
2 - 28
Unit: mm (in.)
Standard
Limit
value
22.944 to 23.000
(0.9039 to 0.9062)
0.006 to 0.018 0.050
(0.0002 to 0.0007) (0.002)
Unit: mm (in.)
Limit
0.15/100
(0.006/3.940)
or less
Measuring
location
• \
Measuring the piston pin-to-boss clearance
C
l
Piston pin
Connecting rod bend

Measuring the connecting rod bend and twist

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]
Using a connecting rod aligner to measure
the rod bend and twist
Using a dial gauge to measure
the connecting rod for bend
Measuring
direction
C
l
l
C 0.05
l
100
C
Connecting rod twist
D
C
A
B
0.05
100