COVER AS-AIR CLEANER 4172437 - Caterpillar

6N6639 Top Ring (1) has the mark "UP-1." 6N6640 Intermediate Ring (2) has the mark "UP-2."**Install 5M5487 Oil Control Ring (3) with the gap in the spring 180° away from the gap in the ring.***"Keystone" style piston rings and grooves in pistons. The 5P4812 KEYSTONE PISTON RING GROOVE GAUGE is necessary for measuring these grooves. Put the pin end (A) of gauge "3" in the groove at four places around the circumference. Do this to both grooves. The flat edge (B) of the gauge must be between grooves (1) and (2). If there is clearance between the flat edge (B) of the gauge and the piston at all test locations, for both grooves, the piston is reusable. If the flat edge (B) is in contact with the piston, at any of the test locations, the piston is not reusable. Install a new piston. (4) Bore in piston for pin ... 2.4506 .0003 in.(62.245 0.008 mm) Clearance between pin and bore in piston ... .0003 to .0012 in.(0.008 to 0.030 mm)Maximum permissible clearance (worn) ... .002 in.(0.05 mm)Pin diameter ... 2.4498 .0002 in.(62.225 0.005 mm) When installed in the engine, the "V" mark on top of the piston must be in alignment with the "V" mark on the cylinder block.