VALVE GP-RELIEF 4432169 - Caterpillar

Cylinder Head Body
Inspect the cylinder head for cracks and obvious physical damage. Pay particular attention to the area around coolant ports for cracks. Check for stripped or damaged threads. 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 head.End Covers
Check for cracks, stripped oil port threads and external damage; and if noted, replace the end cover. If the crankshaft main bearings are installed in the end cover, check for excessive wear and flat spots and replace the end cover if necessary.Crankcase
Check all crankcase surfaces for cracks and damage. Pay particular attention to cooling fins. On compressors where ball bearing main bearings are used the difference between the O.D. of the outer race and the I.D. of the crankcase hole should be 0.000 to 0.038 mm (.0000 to .0015 in) loose. This is to maintain the correct press fit. The crankcase must be replaced if the fit is too loose.On compressors fitted with precision, sleeve main bearings the difference between the O.D. of the crankshaft journal and the main bearing I.D. must not exceed 0.102 mm (.0040 in), or the end cover and main bearing must be replaced.The cylinder bore should be checked with inside micrometers or calipers. Cylinder bores which are scored or out of round by more than 0.0123 mm (.0005 in) or tapered more than 0.0123 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. The cylinder bore must be smooth, straight, and round.Pistons
Check the piston for scores, cracks, or enlarged ring grooves; replace the piston if any of these conditions are found. Measure the diameter of the top of the piston and the top two ring lands. [Compare to cylinder bore and piston diameters to be sure the diametrical clearance is between 0.325 mm (.0128 in) minimum and 0.500 mm (.0177 in) maximum].Check the fit of the wrist pin to the piston. The wrist pin should be a light press fit in the piston. This clearance should not exceed 0.015 mm (.0006 in). 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 by rocking the piston. Clearance for connecting rod wrist pin is 0.023 mm (.0009 in) max. Replace the connecting rod if excessive clearance is found. Wrist pin bushing replacement is not recommended for those connecting rods which incorporate them.Check the fit of the piston rings in the piston ring grooves. Check the ring gap with the rings installed in the cylinder bores. Refer to Figure 10 for correct gap and groove clearances.Crankshaft
Check the crankshaft threads, keyways, tapered ends and all machined and ground surfaces for wear, scores, or damage. Standard crankshaft connecting rod journals are between