TURBOCHARGER GP 9Y1286 - Caterpillar

Illustration 1 g00524461
(1) Markings on pistonEach piston has markings which are stamped on top of the piston. The markings are used to orient the piston assembly to the cylinder block. (2) Piston diameterNote: Measure the piston diameters that are perpendicular to the piston pin bores. Table 1 gives the dimensions for standard pistons and pistons that are oversize.
Table 1
Dimensions for Piston Diameters    
Bore Size     Standard at Assembly     Service Limit (1)    
Standard    
93.955 to 93.985 mm (3.6990 to 3.7002 inch)    
93.770 mm (3.6917 inch)    
Oversize
0.25 mm (0.010 inch)    
94.205 to 94.235 mm (3.7089 to 3.7100 inch)    
94.020 mm (3.7016 inch)    
Oversize
0.50 mm (0.020 inch)    
94.455 to 94.485 mm (3.7187 to 3.7199 inch)    
94.270 mm (3.7114 inch)    
( 1 ) A piston which exceeds this limit must be replaced.
Illustration 2 g00524465
(3) Diameter of piston pin bore Measure the piston pin bore diameter. Subtract the piston pin diameter from the bore diameter. The clearance between the bore and piston pin ... 0.000 to 0.016 mm (0.0000 to 0.0006 inch) (4) Diameter of piston pin Minimum ... 29.994 mm (1.1809 inch) Maximum ... 30.000 mm (1.1811 inch) Service limit ... 0.080 mm (0.0031 inch)
Illustration 3 g00524467
(5) Identification mark on piston ringsInstall the piston rings with the identification mark toward the top. (6) Top piston ringPiston ring end gap for a standard bore Minimum ... 0.30 mm (0.012 inch) Maximum ... 0.50 mm (0.020 inch) Service limit ... 1.50 mm (0.059 inch) (7) Intermediate piston ringPiston ring end gap for standard bore Minimum ... 0.30 mm (0.012 inch) Maximum ... 0.50 mm (0.020 inch) service limit ... 1.50 mm (0.059 inch)Note: The position of the end gap of the oil control ring is 180 degrees from the ends of the ring expander. (8) Oil control piston ringPiston ring end gap for a standard bore Minimum ... 0.30 mm (0.012 inch) Maximum ... 0.50 mm (0.020 inch) Service Limit ... 1.50 mm (0.059 inch)
Illustration 4 g00849910
(9) Side clearance of ring grooveInstall new piston rings in the ring grooves of the piston. Measure the side clearance of the ring groove with a straight edge and feeler gauge. Table 2 gives acceptable clearances of the ring groove.
Table 2
Clearances of the Piston Rings    
Piston Rings     Width of Ring     Side Clearance of Ring Groove     Service Limit (1)    
Top Piston Ring        
0.070 to 0.110 mm (0.0028 to 0.0043 inch)    
0.200 mm (0.0079 inch)    
Intermediate Piston Ring    
2.00 mm (0.079 inch)    
0.045 to 0.085 mm (0.0018 to 0.0033 inch)    
0.150 mm (0.0059 inch)    
Oil Control Piston Ring    
4.00 mm (0.157 inch)    
0.025 to 0.065 mm (0.0010 to 0.0026 inch)    
0.150 mm (0.0059 inch)    
( 1 ) The piston must be replaced if the piston rings exceed these clearances.Position the piston rings according to Illustration 5.
Illustration 5 g00524492
(A) End gap for top piston ring (B) End gap for intermediate piston