Lycoming IVO-540 Series, Operator'S Manual

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LYCOMING OPERATOR’S MANUAL SECTION 5
VO, IVO & TIVO-540 SERIES MAINTENANCE PROCEDURES
d. Oil Pressure Relief Valve –
These engines are equipped with an adjustable oil pressure relief valve
enabling oil pressure to be maintained within specified limits. If the pressure under normal operating
conditions should consistently be out of limits, adjust the valve as follows: With the engine
thoroughly warmed up and running at a maximum of 2200 RPM, observe the reading on the oil
pressure gauge. Stop the engine, remove the crown nut, loosen the locknut and turn the adjusting
screw in the direction required for correction. Screw in to increase pressure, out to decrease pressure.
When the valve has been satisfactorily adjusted, tighten the locknut, install the crown nut and
lockwire.
4. CYLINDERS. Although the complete procedure for disassembly and reassembly is given here, it is
recommended that, as a field operation, cylinder maintenance be confined to replacement of the entire
assembly. Valve replacement should be undertaken only as an emergency measure.
a. Removal of Cylinder Assembly –
(1) Remove exhaust manifold.
(2) Remove rocker box drain tube, intake pipe, baffle and any clips that might interfere with the
removal of the cylinder.
(3) Disconnect ignition harness elbows from spark plugs and remove spark plugs.
(4) Remove rocker box cover and rotate crankshaft until piston is approximately at top center of the
compression stroke. This approximate position may be located by observing top of piston through
the spark plug hole and also noting the valve action.
(5) Remove rocker shaft covers from cylinder head.
(6) Slide valve rocker shafts from cylinder head far enough so that the valve rockers and thrust
washers can be removed. Remove rotator cap from exhaust valve stem. The rocker shafts can be
removed when the cylinder is removed from the engine.
(7) Remove push rods by grasping ball end and pulling out of shroud tube. Turn shroud tube 90°
either way, this releases detent from spring. Remove shroud tubes by first releasing them from the
seal seat in the cylinder head and then withdrawing from the crankcase. Remove shroud tube
sleeves and seals from outer end of shroud tube and seals from crankcase. Discard all seals. Place
washers, springs and sleeves in proper compartment of cleaning basket.
NOTE
Hydraulic tappets, push rods, rocker arms and valves must be assembled in the same
location from which they were removed.
(8) Remove cylinder base hold down nuts and pull cylinder directly away from the crankcase. Be
careful not to allow the piston to drop against the crankcase as the piston leaves the cylinder.
(9) Use the old cylinder base oil seal ring and criss-cross over the cylinder base studs and around
connecting rods to keep rod from striking crankcase.
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