5-12. PISTON ASSEMBLY MAINTENANCE INSTRUCTIONS - Continued
R E P A I R
If piston (4) is reusable, and ring set is to be re-
placed, proceed as follows:
Using a piston ring expander, remove the pis-
ton rings (1, 2, and 3) and discard the rings.
C A U T I O N
Do not expand rings more than neces-
sary to just clear the outside diameter
of the piston (4). Permanent damage to
the ring may result.
Using the piston ring expander; install the oil
control ring (1) in the lower groove of piston
(4), middle ring (2) in middle groove, and com-
pression ring (3) in top groove.
The middle ring (2) installs with the
stepped down shoulder on the bottom
side. Each ring is marked with the letter
R, which designates the side which must
be toward top of piston.
If the piston requires replacement, it is rec-
ommended that the rings be replaced
along with the cylinder (Para. 5-11).
If not already installed, install the piston
rings (1,2 and 3), see REPAIR above.
Set the piston assembly (4) upside down on
clean workbench, ensure that the gaps of piston
rings are staggered at 120° intervals.
Compress the piston rings with a ring compressor.
Place the cylinder (5) upside down on a clean
Position the piston assembly (4) with ring com-
pressor on to the cylinder (5) and push the piston
assembly into the cylinder.
Remove the ring compressor and adjust position
of piston assembly (4) in cylinder so the piston
pin bore of piston is fully exposed below the cylin-
der (5) liner.
Install the assembled cylinder and piston assem-
bly over studs, engaging the top of connecting
rod with piston assembly (4).
Install piston pin (6) in piston and connecting rod
bore, tapping with a plastic tipped hammer. Cen-
ter the piston pin and secure with replacement
lock rings (7).