Piston Removal - Lycoming IO-390-D Series Maintenance Manual

8. Piston Removal

NOTICE: During removal of each piston pin (Figure 18), the piston will disconnect from the
connecting rod.
A. Support the piston and remove the two piston pin plugs (Figure 18) and piston pin from the
piston.
CAUTION
NOTICE: During piston removal, support the connecting rod to prevent damage to the
connecting rods and crankcase:
B. Remove the piston from the connecting rod.
C. Install Torque Hold-Down Plates (ST-222) or equivalent as shown in Figure 19.
CAUTION
D. Start from the top down, use the a commercially available piston ring expander tool to remove
the two top compression rings and the oil regulating piston expander ring (Figure 18).
72-30
Page 208
Piston Assembly
ANYTIME A CYLINDER IS REMOVED, INSTALL TORQUE HOLD-
DOWN PLATES OR EQUIVALENT TO ENSURE A UNIFORM LOAD
ON THE MAIN BEARINGS IN THE CRANKCASE.
Torque Hold-Down Plates (ST-222)
DURING REMOVAL OF THE THREE PISTON RINGS IN THE NEXT
STEP, USE CARE NOT TO SCRATCH THE PISTON.
IO-390-D Series Engine Maintenance Manual
IO-390-D Series Engine Maintenance Manual
Figure 18
Figure 19
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March 2020