GEAR 1786550 - Caterpillar

Cylinder Head Body
Inspect the cylinder head for cracks or damage. With the cylinder head and head gasket secured to a flat surface or crankcase, apply shop air pressure to one of the coolant ports with all others plugged, and check for leakage by applying a soap solution to the exterior of the body. If leakage is detected, replace the compressor.End Covers
Check for cracks and external damage. If crankshaft main bearing (32) is installed in end cover (34), check for excessive wear and flat spots and replace if necessary.Crankcase
Check all crankcase surfaces for cracks and damage. On compressors where ball bearing main bearings are used the difference between the OD of the outer race and the ID of the crankcase hole should be 0.007 mm (.0003 in) tight to 0.058 mm (.0023 in) loose. This is to maintain the correct fit. The compressor must be replaced if the fit is too loose.On compressors fitted with precision, sleeve main bearings, the difference between the OD of the crankshaft journal and the main bearing ID must not exceed 0.13 mm (.005 in). If the clearance is greater than 0.13 mm (.005 in) the bearing must be replaced.The cylinder bores should be checked with inside micrometers or calipers. Cylinder bores which are scored or out of round by more than 0.013 mm (.0005 in) or tapered more than 0.013 mm (.0005 in) should be rebored or honed oversize. Oversized pistons and piston rings are available in 0.25 mm (.010 in), 0.50 mm (.020 in) and 0.75 mm (.030 in) oversizes. Cylinder bores must be smooth, straight and round. Clearance between the cast iron pistons and cylinder bores should be between 0.05 mm (.002 in) minimum and 0.10 mm (.004 in) maximum.Piston Rings
Check the pistons for scores, cracks or enlarged ring grooves; replace the pistons if any of these conditions are found. Measure each piston with a micrometer in relation to the cylinder bore diameter to be sure the diametrical clearance is between 0.05 mm (.002 in) minimum and 0.10 mm (.004 in) maximum.Check the fit of the wrist pins to the pistons and connecting rod bushings. The wrist pin should be a light press fit in the piston. If the wrist pin is a loose fit, the piston and pin assembly should be replaced. Check the fit of the wrist pin in the connecting rod bushing by rocking the piston. This clearance should not exceed 0.0178 mm (.0007 in). Replace the connecting rod and cap assembly which includes the wrist pin bushings if excessive clearance is found. Check the fit of the rings in the piston ring grooves. Check the ring gap with the rings installed in the cylinder bores. Refer to Fig 13 for correct gap and groove clearances.
Fig 13 Ring ConfigurationCrankshaft
Check the crankshaft threads, keyways, tapered ends and all machined and ground surfaces for wear, scores, or damage. Standard crankshaft journals are 28.555 mm (1.1242 in) to 28.575 mm (1.1250 in) in diameter. If the crankshaft journals are excessively scored