Cleaning and Inspection
INSPECTIONCrankshaft Main Journals
1. The crankshaft journals should be checked for excessive wear, taper and scoring. Limits of taper or out-of-round on any crankshaft journals should be held to 0.025 mm. Journal grinding should not exceed 0.305 mm under the standard journal diameter. Do NOT grind thrust faces of Number 3 main journal. Do NOT nick crank pin or journal fillets. After grinding, remove rough edges from crankshaft oil holes and clean out all passages.
CAUTION: With the nodular cast iron crankshafts used it is important that the final paper or cloth polish after any journal regrind be in the same direction as normal rotation in the engine.
Crankshaft Bearing Clearance
1. The total clearance of the main bearings can only be determined by removing the weight of the crankshaft. This is accomplished by having the engine turned upside down on the engine stand. This will remove all the crankshaft weight off the bearing surface.
2. Place a piece of Plastigage across the entire width of the bearing shell in the bedplate approximately 6.35 mm (0.25 inch) off center and away from the oil holes. In addition, suspect areas can be checked by placing the Plastigage in the suspect area. Torque the bearing bedplate bolts of the bearing being checked to the proper specifications.
CAUTION: Do not rotate crankshaft, or the Plastigage may be smeared.
3. Remove the bedplate and compare the width of the flattened Plastigage with the metric scale provided on the package.
Standard value: 0.022 - 0.062 mm (0.0009 - 0.0024 inch)
Main Bearing Bolts
1. Since the main bearing bolts are torqued using a new procedure, they should be examined BEFORE reuse. If the threads are necked down, replace the bolts.
2. Necking can be checked by holding a scale or straight edge against the threads. If all the threads do not contact the scale, the bolt should be replaced.
Checking Crankshaft End Play
1. Mount a dial indicator to front of engine, locating probe on nose of crankshaft.
2. Move crankshaft all the way to the rear of its travel using a lever inserted between a main bearing cap and a crankshaft cheek, using care not to damage any bearing surface. Do not loosen main bearing cap.
3. Zero the dial indicator.
4. Move crankshaft all the way to the front and read the dial indicator.
Standard value:
0.09 - 0.24 mm (0.0035 - 0.0094 inch)
Limit:
0.37 mm (0.015 inch)
5. Replace No.3 main bearing if limit is exceeded and remeasure.
6. Replace crankshaft if limit is still exceeded.
Optional Crankshaft End Play Check
1. Move crankshaft all the way to the rear of its travel using a lever inserted between a main bearing cap and a crankshaft cheek, using care not to damage any bearing surface. Do not loosen main bearing cap.
2. Use a feeler gauge between number three thrust bearing and machined crankshaft surface to determine end play.