TM-9-2815-202-34 Technical Manual for 8V71T Engines for M109 Howitzer Download
Page 518 of 670
TABLE 6-2 TM9-2815-202-34 6-34. PISTON AND CONNECTING ROD MAINTENANCE (TRUNK TYPE) (Cont) • • (2) (3) NOTE Use feeler gage to check piston to liner clearance. Use a spring scale attached to feeler gage to measure amount of force in pounds required to withdraw feeler gage from between piston and liner. Select feeler gage with thickness requiring six pounds pull to move. Piston to liner clearance is 0.001 inch greater than thickness of feeler gage used. For example, a 0.004 inch feeler gage indicates 0.005 inch clearance when withdrawn with a six pound pull. Feeler gage must be perfectly flat and free of nicks and bends. With cylinder liner (1) installed in cylinder block (6), hold piston (10) upside down in liner and measure clearance in four places, 90 degrees apart. Clearance must be 0.0045 to 0.0083 inch with new parts. Allow a maximum clearance of 0.0120 inch for used parts. If binding occurs between piston and liner, remove piston and examine piston and liner for burrs. Remove burrs on piston with a fine stone. Remove burrs in liner with fine flat hone and recheck clearance. f. Fitting Piston Rings (1) Insert ring inside cylinder liner in normal area of ring travel. Using piston to push ring down, measure ring gap with feeler gage. Refer to Table 6-2 for ring gap specifications. Repeat procedure for balance of compression and oil rings. File or stone both ends of compression ring from outer surface to inner surface to prevent chipping or peeling of chrome plating on ring. (2) File ends of compression ring if ring gap is too small. Ends of ring must remain square, and chamfer on outer edge must be approximately 0.015 inch. 6-36