Mitsubishi diesel engines - Measuring the Connecting Rod End Play

ENGINE MAIN PARTS - INSPECTION AND CORRECTION
2 - 29
3.6 Measuring the connecting rod end play
Install the connecting rod and the rod cap onto
the mating crank pin. Tighten the cap nuts to the
specified torque. Using a thickness gauge,
measure the gap (end play).
If the measured value exceeds the limit, replace
the connecting rod and the rod cap.
Unit: mm (in.)
Standard value Limit
Connecting rod end
play
0.10 to 0.35
(0.004 to 0.014)
0.50
(0.012)
3.7 Inspecting the oil clearance for
connecting rod bearings
(1) Install the connecting rod bearings (upper and
lower) into the connecting rod large end. Tighten
the cap nuts to the specified torque. Measure the
inner diameter of the bearings.
(2) Measure the diameter of the mating crank pin.
The difference between the bearing inner
diameter and the crank pin diameter is the oil
clearance for the bearings.
Unit: mm (in.)
Nominal
value
Standard
value
Limit
Crank pin
diameter
φ48
(1.8912)
47.950 to 47.964
(1.8892 to 1.8897)
―
Oil clearance
for connecting
rod bearings
―
0.025 to 0.072
(0.0010 to 0.0028)
0.150
(0.0059)
(3) If the measured oil clearance exceeds the limit,
replace the bearings. With the new bearings
installed, measure the oil clearance again.
(4) If the measured oil clearance still exceeds the
limit, use the undersize bearings [0.25 mm
(0.0098 in.), 0.50 mm (0.0197 in.), 0.75 mm
(0.0295 in.) U.S.]
Also, grind the crank pin accordingly to the
finished dimension shown below.
Crank pin ground dimensions
Unit: mm (in.)
Finished dimension
0.25 (0.0098)
φ47.75
-0.035
-0.050
(1.881
-0.0014
-0.0020
)
0.50 (0.0197)
φ47.50
-0.035
-0.050
(1.871
-0.0014
-0.0020
)
Crank pin
undersize
0.75 (0.0295)
φ47.25
-0.035
-0.050
(1.861
-0.0014
-0.0020
)
Measuring the connecting rod end play
Measuring the connecting rod bearings
inner diameter
Measuring the crank pin diameter
Measuring
direction
Measuring
location
Thickness gauge
Tightening torque
32.4 to 37.3 N
m
(3.3 to 3.8 kgf
m)
[23.9 to 27.5 lbf
ft]
Measuring
direction
Measuring
location
Tightening torque
32.4 to 37.3 N
m
(3.3 to 3.8 kgf
m)
[23.9 to 27.5 lbf
ft]