Crankshaft Pin and Connecting Rod Bearing Inspection
Crankshaft Pin and Connecting Rod Bearing Inspection
Piston, Piston Ring and Connecting Rod Disassembly and Reassembly
Crankshaft Pin Diameter
- Use micrometer to measure crankshaft pin diameter at several points and calculate taper and out-of-round conditions.
Replace crankshaft or regrind crankshaft pin to undersize and use undersize bearing if calculated taper and/or out-of-round is out of their service limit.
Crankshaft pin diameter
Standard: 49.982 - 50.000 mm (1.9678 - 1.9685 in.)
Crankshaft pin taper ([a] - [b]) and out-of-round ([1] -[2])
Limit: 0.01 mm (0.0003 in.)
Connecting Rod Bearing General Information
- Service connecting rod bearings are available in five standard sizes and 0.25 mm (0.0098 in) undersize bearing. The difference of those sizes is thickness.
- Specified colors for identification of sizes are painted at specified location (1) as shown in figure.
Connecting Rod Bearing Visual Inspection
Check bearing shells for signs of fusion, pitting, burn or flaking and observe contact pattern. Replace connecting rod bearings if any abnormalities are found.
Connecting Rod Bearing Clearance
NOTE:
Using connecting rod bolts that are deformed exceeding the service limit could lead to engine problems.
After checking connecting rod bearing clearance, make sure that connecting rod bolts are not deformed exceeding the service limit referring to "Connecting rod bolt deformation" under Piston Pin and Connecting Rod Inspection Piston Pin and Connecting Rod Inspection.
NOTE:
Do not rotate crankshaft while gauging plastic is installed.
1) Clean connecting rod bearings and crankshaft pin.
2) Place plastic gauge (1) with the same width as the crankshaft pin, so that it fits over the bearing, parallel to the crankshaft, avoiding the oil hole.
3) Install connecting rod bearings and its cap. Removal and Installation
4) After three minutes elapsed, remove cap and use a scale (2) on plastic gauge envelope to measure plastic gauge (1) width at the widest point.
Connecting rod bearing clearance
Standard: 0.045 - 0.063 mm (0.0017 - 0.0024 in.)
Limit: 0.065 mm (0.0025 in.)
If measured oil clearance is less than standard value or more than service limit, replace connecting rod bearings with new ones referring to Selection of Connecting Rod Bearing
, and recheck oil clearance.
Depending on measured oil clearance with new bearing, select other bearings using the following procedures and recheck oil clearance:
- More than standard:
Replace bearings with one size thicker or regrind crankshaft pin to under size and use 0.25 mm (0.0098 in) undersize bearings.
- Less than standard:
Replace bearings with one size thinner or regrind crankshaft pin to under size and use 0.25 mm (0.0098 in) undersize bearings.
Selection of Connecting Rod Bearing
Standard size
1) Check connecting rod big-end inside diameter using the following procedure:
- There is stamped number (any of "1", "2" or "3") on each connecting rod and it cap as shown in figure.
- That number represents connecting rod big-end inside diameter as follows.
Connecting rod big-end inside diameter
2) Check crankshaft pin diameter using the following procedure:
- There are four stamped alphabets (any of "A", "B" or "C") on crank web No.5 as shown in figure.
- Those alphabets represent crankshaft pin diameter as follows:
Crankshaft pin diameter
3) Determine new standard bearings to be installed to connecting rod big-end from numbers stamped on connecting rods and the caps and alphabets stamped on crank web No. 5 using the following table:
Connecting rod bearing cross-reference selection table
Undersize
4) Determine target diameter of crankshaft pin for regrinding according to the following procedure.
a) Assemble connecting rod, connecting rod cap and undersize bearings (0.25 mm (0.0098 in.)), referring to step 2) to 5) of "Installation" under Removal and Installation Piston, Piston Ring and Connecting Rod Removal and Installation.
b) Use a bore gauge to measure connecting rod bearing inside diameter "a".
c) Calculate target diameter using the following formula:
Formula for target diameter of crankshaft pin
A = B - 0.054 mm (0.0021 in.)
A: Target diameter of crankshaft pin B: Measured connecting rod bearing inside diameter "a".
5) Grind crankshaft pin to target diameter.
6) Check connecting rod bearing oil clearance.
