TM 10-4930-351-14
0109 00
INSTALL PISTON RINGS (Refer to Figure 5)
INITIAL SET-UP:
Tools:
Materials/Parts Required
Caliper, Vernier
None
(WP 0113 00, Item 3)
Feeler Gauge
Equipment Condition:
(WP 0113 00, Item 3)
Piston and rings removed
1.
Inspect cylinder, piston and piston rings.
a.
Insert the first compression ring (1) in the top of the cylinder. Measure and record the gap between the ends of the
ring. Remove the ring and repeat the procedure with the second compression ring (2) and the oil scraper ring (3). If
the ring gap is more than 0.02 inches or less than 0.01 inches, replace the cylinder.
b.
Measure and record the piston skirt diameter (4) between 0.200 and 0.393 inches from the base of the piston skirt.
c.
Measure and record the inside diameter of the cylinder.
d.
Subtract the piston skirt diameter (4) from the cylinder inside diameter. The difference should be 0.002 - 0.003
inches. If clearance is greater than 0.003 inches, replace cylinder/piston.
2.
Thoroughly clean piston (5) ensuring all carbon deposits are removed from piston top and ring grooves.
3.
Install rings on piston (5) using the following steps:
NOTE
Install piston rings from top of piston.
a.
Install oil scraper ring (3) in bottom piston groove. Rotate ring to place gap in line with one end of piston pin (6).
b.
Install second compression ring (2) in middle piston ring groove with internal bevel toward top of piston (5). Rotate
ring to place gap 120 in either direction from the gap in the oil scraper ring (3).
c.
Install first compression ring (1) in top piston groove. Rotate ring to place gap midway on the longer arc between oil
scraper ring (3) gap and second compression ring (2) gap (120 from each of the other two rings).
4.
Inspect rings to ensure all three piston rings move freely in grooves. Check the clearance between each piston groove
and each piston ring as follows. If any measurement exceeds the specified value, replace the piston.
a.
First compression ring (1) must have 0.009 inches clearance.
b.
Second compression ring (2) must have 0.007 inches clearance.
c.
Oil scraper ring (3) must have 0.006 inches clearance
0109 00-6
