Piston Pins and Connecting Rods Inspection
Piston Pin
Visual inspection
Check piston pin, connecting rod small end bore and piston bore for wear or damage, paying particular attention to condition of small end bore bush. If pin, connecting rod small end bore or piston bore is badly worn or damaged, replace pin, connecting rod and/or piston.
Piston pin clearance
Check piston pin clearance in small end and piston. Replace connecting rod and/or piston if its small end is badly worn or damaged or if measured clearance exceeds limit.
Piston pin clearance in connecting rod small end
Standard: 0.003 – 0.014 mm (0.00012 – 0.00055 in.)
Piston pin clearance in piston
Standard: 0.006 – 0.017 mm (0.00024 – 0.00066 in.)
Small-end bore
20.003 – 20.011 mm (0.7876 – 0.7878 in.)
Piston pin dia.
19.997 – 20.000 mm (0.7873 – 0.7874 in.)
Piston bore
20.006 – 20.014 mm (0.7877 – 0.7879 in.)
Connecting Rod
Big-end side clearance
Check big-end of connecting rod for side clearance, with rod fitted and connected to its crank pin in the normal manner. If measured clearance is found to exceed its limit, replace connecting rod.
Big-end side clearance
Standard: 0.25 – 0.40 mm (0.0098 – 0.0157 in.)
Limit: 0.55 mm (0.0217 in.)
Connecting rod alignment
Mount connecting rod on aligner to check it for bow and twist. If limit is exceeded, replace it.
Connecting rod alignment
Limit on bow: 0.05 mm (0.0020 in.)
Limit on twist: 0.10 mm (0.0039 in.)
Connecting rod bolt deformation (Plastic deformation tightening bolt)
Measure connecting rod (1) bolt (2) for diameter “A” on 32 mm (1.25 in.) from bolt mounting surface and diameter “B” on 40 mm (1.57 in.) from bolt mounting surface by using a micrometer (3).
Calculate difference in diameters (“A” – “B”). If it is exceeds limit, replace connected rod (1).
Connecting rod bolt measurement points
“a”: 32 mm (1.25 in.)
“b”: 40 mm (1.57 in.)
Connecting rod bolt diameter difference
Limit (“A” – “B”): 0.1 mm (0.004 in.)