DETROIT DIESEL 53
1.2.1
V A L V E AND INJECTOR OPERATING MECHANISM
Three rocker arms are provided for each cylinder; the
1. Adjusting valve clearance.
two outer arms operate the exhaust valves and the
2. Removing and installing a valve spring.
center arm operates the fuel injector.
3. Removing and installing a rocker arm.
Each set of rocker arm assemblies pivots on a shaft
supported by two brackets. A single bolt secures each
4. Removing and installing a rocker arm shaft or shaft
bracket to the top of the cylinder head. Consequently,
bracket.
the removal of two bracket bolts permits the rocker
arm assembly for one cylinder to be raised, providing
5. Removing and installing an injector.
easy access to the fuel injector and valve springs.
It is also possible, if occasion requires, to remove or
The rocker arms are operated by the camshaft through
replace a push rod, push rod spring, spring seats or
cam followers and short push rods extending through
cam follower without removing the cylinder head.
the cylinder head (Fig. 1).
These parts, however, are more easily changed from
the lower side of the cylinder head when the head is
Each cam follower operates in a bore in the cylinder
off the engine. Both methods are covered in this
head. A guide for each set of three cam followers is
Section.
attached to the bottom of the cylinder head to keep
the follower rollers in line with the cams and serves as
To remove and install valves, valve guides, valve seat
a retainer during assembly and disassembly.
inserts and to recondition valves and valve seats, the
cylinder head must be removed. Exhaust valves, guides
A coil spring, located inside of each cam follower, is
and inserts are covered in Section 1.2.2.
held in place in the cylinder head by a spring seat and
spring seat retainer.
Several operations may be performed on the valve
Lubrication
mechanism without removing the cylinder head from
the cylinder block, while the head must be removed
The valve and injector operating mechanism is
for certain other operations. The operations NOT
lubricated by oil from a longitudinal oil passage, on
requiring removal of-the cylinder head are:
the camshaft side of the cylinder head, which connects
with oil passages in the cylinder block. Oil from this
Fig. 1 - Injector Operating Mechanism (In-Line
Engine Shown)
Fig. 2 - Cam Follower and Guide Location
SEC. 1.2.1 Page 1
July, 1972
