Cylinders - Lycoming O-320 76 Series Operator's Manual

LYCOMING SERIES OPERATOR'S MANUAL
O-320
(7) Remove cylinder base nuts, then remove cylinder by pulling directly away from crankcase. Be
careful not to allow the piston and connecting rod to drop against the crankcase, as the piston
leaves the cylinder.
b. Removal of Valves and Valve Springs from Cylinder – Place the cylinder over a block of wood so as to
hold the valves in a closed position. Compress the valve springs using the valve spring compressor.
Remove the split keys from the end of the valve stem. The valve springs and valve spring seats may
now be removed from the cylinder head. Hold the valve stems so that the valves will not fall out and
remove the cylinder from the holding block. The valves may now be removed from the inside of the
cylinder.
c. Removal of Piston from Connecting Rod – Remove the piston pin plugs. Insert piston pin puller
through piston pin, assemble puller nut; then proceed to remove piston pin. Do not allow connecting
rod to rest on the cylinder pad of the crankcase. Support with heavy rubber bands, discarded cylinder
base oil ring seals or any other method.
d. Removal, Disassembly, Cleaning, Inspection and Reassembly of Hydraulic Lifters –
(1) Lifter can be withdrawn by fingers.
(2) Being careful not to scratch socket, insert a screw driver into lifter and push. This will force the
trapped oil out of the vent hole and release the pressure on the circlip.
(3) Remove and discard the circlip.
UPON RELEASE, CIRCLIP MAY SPRING UP WITH GREAT FORCE. BE CAREFUL!
(4) Remove the spring, plunger and socket from the lifter and clean the parts and the lifter body in
solvent. Inspect the lifter body for the following imperfections:
Spalling – If the face of the lifter shows small nicks or indentations near the center of the face, it is
considered pitted or spalled. The pitting will constitute small irregular holes, not to be confused
with Rockwell hardness check marks which are round and even. The area covered by spalling will
vary with different lifters, but regardless of the degree, the lifter must be replaced.
Scoring – The lifter face is scored when small scratch like lines are found on the surface. These
marks are usually found near the outer edge of the face and will appear to radiate from the center.
Other scoring marks may be present and extend to the center of the lifter face. Any lifter, with this
condition in evidence, must be replaced.
Face Wear – The operation of the lifter provides that the lifter rotates during wiping operation of
the cam. This will form a groove, or path. This path will extend all the way across the face and
deeper penetrations will be noted at the center of the face. If the wear is excessive, it will be
noticeable to the touch if the fingernail is rubbed across the lifter face. This condition requires
replacement of the lifter body.
MAINTENANCE PROCEDURES
CAUTION
SECTION 5
5-7