Piston and Connecting Rod
CLEANINGPistons
CAUTION: DO NOT use bead blast to clean the pistons. DO NOT clean the pistons and rods in an acid tank.
Clean the pistons and pins in a suitable solvent, rinse in hot water and blow dry with compressed air. Soaking the pistons over night will loosen most of the carbon build up. De-carbon the ring grooves with a broken piston ring and again clean the pistons in solvent. Rinse in hot water and blow dry with compressed air.
Connecting Rods
Clean the connecting rods in a suitable solvent rinse in hot water and blow dry with compressed air.
INSPECTION
Pistons
Fig. 236
Inspect the pistons for damage and excessive wear. Check top of the piston, ring grooves, skirt and pin bore. Measure the piston skirt diameter (Fig. 236). If the piston is out of limits, replace the piston.
Fig. 237
The upper groove only needs to be inspected for damage. Use a new piston ring to measure the clearance in the intermediate ring groove (Fig. 237). If the clearance of the intermediate ring exceeds 0.152 mm (0.006 inch), replace the piston.
Use a new oil ring to measure the clearance in the oil groove (Fig. 237). If the clearance exceeds 0.127 mm (0.005 inch), replace the piston.
Fig. 238
Measure the pin bore (Fig. 238). The maximum diameter is 40.025 mm (1.5758 inch). If the bore is over limits, replace the piston.
Fig. 239
Inspect the piston pin for nicks, gouges and excessive wear. Measure the pin diameter (Fig. 239). The minimum diameter is 39.990 mm (1.5744 inch). If the diameter is out of limits, replace the pin.
Connecting Rods
Inspect the connecting rod for damage and wear. The I-Beam section of the connecting rod cannot have dents or other damage. Damage to this part can cause stress risers which will progress to breakage.
Fig. 240
Measure the connecting rod pin bore (Fig. 240). The maximum diameter is 40.042 mm (1.5764 inch). If out of limits, replace the connecting rod.