9 - 32
ENGINE
INTAKE/EXHAUST VALVES & SEATS (Continued)
Fig. 34 Checking Valve Tip Height and Valve Spring
Installed Height
1 - SPRING RETAINER
2 - GARTER SPRING
3 - VALVE SPRING SEAT TOP
4 - CYLINDER HEAD SURFACE
ROCKER ARM / ADJUSTER
ASSEMBLY
DESCRIPTION
DESCRIPTION - ROCKER ARM
Rocker arms are made of light weight permanent
mold aluminum alloy with a roller type follower oper-
ating against the camshaft (Fig. 35). The valve actu-
ating end of the rocker arms are machined to retain
hydraulic lash adjusters, eliminating the need for
manual valve lash adjustment.
DESCRIPTION - ROCKER ARM SHAFTS
The rocker arm shafts (Fig. 36) are tubular steel
and are supported by several forged aluminum alloy
pedestals, which are fastened to the cylinder head.
Four shafts are used, one for each intake and
exhaust rocker arm bank on each cylinder head. The
shafts are hollow to provide a duct for lubricating oil
flow from the cylinder head to the valve mechanisms.
One hollow dowel per pedestal is used to locate the
pedestal to the cylinder head, orient the exhaust
rocker shaft, and serve as a cam bearing oil feed pas-
sage.
Fig. 35 Rocker Arm Assembly
1 - RETAINER
2 - SWIVEL PAD
3 - ROLLER
Fig. 36 Rocker Arms and Shafts
DIAGNOSIS AND TESTING
LASH ADJUSTER (TAPPET) NOISE DIAGNOSIS
Proper noise diagnosis is essential in locating the
source of a NVH complaint. Locating a lash adjuster
(tappet) type noise can sometimes be difficult. As a
result, an initial misdiagnosis may occur.
Refer to the following chart indicating possible lash
adjuster (tappet) noise sources and possible sources
that could lead to a misdiagnosis.
Refer to Lash Adjuster (Tappet) Noise Chart for
Possible Causes and Correction of a lash adjuster
(tappet) type noise.
LH