Lycoming TEO-540-C1A Maintenance Manual page 244

WARNING A STUCK VALVE CAN CAUSE ENGINE DAMAGE.
NOTICE: If one valve is sticking, examine all intake and exhaust valves on all of the engine
cylinders.
The exhaust valve and guide must be examined to measure valve stem movement to identify
excessive wear (bell-mouthing) of the exhaust valve guide and carbon build-up between the
valve guide and valve stem which can cause valve sticking
Refer to the latest revision of Service Bulletin No. SB-388, Service Instruction No. SI-1485, and
Service Letter L197 for additional details.
NOTICE: The Gage (ST-310) is used to examine angular-type valves on engine cylinders.
Although Gage (ST-310) and a feeler gage can be used to measure valve stem
movement, a modified Gage (ST-310) (Figure 4) and a dial indicator are a faster and
easier means to measure valve stem movement, valve guide wear, and carbon build-
up per this procedure.
NOTICE: Do not intermix valve and cylinder components between cylinders. Re-install
serviceable parts in the same cylinder.
A. Examine the exhaust valve and guide on each cylinder as follows:
(1) Disconnect the battery.
(2) Make sure the engine is cool.
(3) Remove the screws, rocker box cover (Figure 5) and gasket from the cylinder head.
Discard the gasket.
(4) Remove the nuts, lock washers, valve rocker shaft cover, and valve rocker shaft cover
gasket. Discard the lock washers and valve rocker shaft cover gasket.
(5) Remove the valve rocker shaft, valve rocker shaft bushing, rocker assembly, and washer.
72-30
Page 214
Figure 4
Details for Modifying Tool P/N ST-310
TEO-540-C1A Engine Maintenance Manual
TEO-540-C1A Engine Maintenance Manual
© 2018 Avco Corporation. All Rights Reserved
November 2018