Crankshaft: Service and Repair

CRANKSHAFT AND PISTON

CRANKSHAFT AND CRANKSHAFT BEARING
1. Clean crankshaft completely and check for cracks by means of red lead check etc., and replace if defective.





2. Measure the crankshaft bend, and correct or replace if it exceeds the limit.

NOTE: If a suitable V-block is not available, install #1 and #5 crankshaft bearing on cylinder block, position crankshaft on these bearings and measure crankshaft bend using a dial gauge.

Crankshaft bend limit: 0.035 mm (0.0014 inch)
3. Inspect the crank journal and crank pin for wear. If they are not within the specifications, replace bearing with a suitable (undersize) one, and replace or recondition crankshaft as necessary.





When grinding crank journal or crank pin, finish them to the specified dimensions according to the undersize bearing to be used.
Crank pin:
Out-of-roundness 0.003 mm (0.0001 inch)
Cylindricality 0.004 mm (0.0002 inch)
Grinding limit 51.750 mm (2.0374 inch) dia. or less





Crank journal:
Out-of-roundness 0.005 mm (0.0002 inch)
Cylindricality 0.006 mm (0.0002 inch)
Grinding limit 59.750 mm (2.3524 inch) dia. or less





4. Measure the thrust clearance of crankshaft at center bearing. If the clearance exceeds the limit, replace bearing.
Crankshaft thrust clearance:
Standard 0.030 - 0.115 mm (0.0012 - 0.0045 inch)
Limit 0.25 mm (0.0098 inch)
5. Inspect individual crankshaft bearings for signs of flaking, seizure, melting, and wear.





6. Measure the oil clearance on each crankshaft bearing by means of plastigauge. If the measurement is not within the specification, replace defective bearing with an undersize one, and replace or recondition crankshaft as necessary.