5. Loosen the locknuts at the upper ends of the push
rods, next to the clevises, and unscrew the rocker arms
from the push rods.
Some service operations may be performed on the
NOTE: If the rocker arms and shafts
valve and injector operating mechanism without
from two or more cylinders are to be
removing the cylinder head:
removed. tag them so they may be
reinstalled in their original positions.
Adjust valve clearance.
Replace a valve spring.
Replace a rocker arm.
Replace a rocker arm shaft or bracket.
Wash the rocker arms, shaft, brackets and bolts with
Replace a fuel injector.
clean fuel oil. Use a small wire to clean out the drilled
oil passages in the rocker arms and rocker shaft bolts.
It is also possible to replace a push rod. push rod
Dry the parts with compressed air.
spring, the spring seats or a cam follower without
removing the cylinder head. However, these parts are
Inspect the rocker arm shaft and rocker arm bushings
more easily changed from the lower side when the
for wear. A maximum shaft to bushing clearance of
cylinder head is off the engine. Both methods are
.004" is allowable with used parts (refer to Page 10-2-
covered in this section.
137). Service replacement bushings must be reamed to
size after installation.
To replace the exhaust valves, valve guides and valve
seat inserts, the cylinder head must be removed (refer
Inspect the rocker arms for galling or wear on the pallets
(valve or injector contact surfaces). If worn, the surface
may be refaced up to a maximum of .010". However,
proceed with caution when surface grinding to avoid
Remove Rocker Arms and Shaft
overheating the rocker arm. Maintain the
1. Clean and remove the valve rocker cover.
2. Remove the fuel pipes from the injector and the fuel
NOTE: Immediately after removing the
fuel pipes, cover the injector fuel inlet
and outlet openings with shipping caps
to prevent dirt or foreign material from
3. Turn the crankshaft, or crank the engine with the
starting motor, to bring the injector and valve rocker
arms in line horizontally.
NOTE: Do not bar the crankshaft in a
left-hand direction of rotation with a
wrench or barring tool on the crankshaft
bolt, because the bolt may be loosened.
4. Remove the two bolts which secure the rocker arm
shaft brackets to the cylinder head. Remove the
brackets and shaft.
CAUTION: When removing the rocker
Fig. 3. Removing Push Rod from Upper Side of
arm shaft, fold the three rocker arms
Cylinder Head using Tool J 3092-01
back just far enough so the shaft can be
removed. Do not force the rocker arms
all the way back with the shaft in place
as this may impose a load that could