NOTE: Examples used in this article are general in nature and do not necessarily relate to a specific engine or system. Illustrations and procedures have been chosen to guide mechanic through engine overhaul process. Descriptions of processes of cleaning, inspection, assembly and machine shop practice are included.
Always refer to appropriate engine overhaul article, if available, in the ENGINES section for complete overhaul procedures and specifications for the vehicle being repaired.
Rocker Studs
Rocker studs are either threaded or pressed in place. Threaded studs are removed by locking 2 nuts on the stud.
Unscrew the stud by turning the jam nut. Coat new stud threads with Loctite and install. Tighten to specification.
Pressed-in stud can be removed using a stud puller. Ream stud bore to proper specification and press in a new oversize stud. Pressed-in studs are often replaced by cutting threads in the stud bore to accept a threaded stud.
Rocker Arms & Shafts
Mark rocker arms for location. Remove rocker arm retaining bolts. Remove rocker arms. Inspect rocker arms, shafts, bushings and pivot balls (if equipped) for excessive wear. Inspect rocker arms for wear in valve stem contact area. Measure rocker arm bushing I.D. Replace bushings if excessively worn.
The rocker arm valve stem contact point may be reground, using special fixture for valve grinding machine.
Remove minimum amount of material as possible. Ensure all oil passages are clear. Install rocker arm components in original location. Ensure rocker arm is properly seated in push rod. Tighten bolts to specification. Adjust valves if required. See VALVE ADJUSTMENT.
PUSH RODS
NOTE: Examples used in this article are general in nature and do not necessarily relate to a specific engine or system. Illustrations and procedures have been chosen to guide mechanic through engine overhaul process. Descriptions of processes of cleaning, inspection, assembly and machine shop practice are included.
Always refer to appropriate engine overhaul article, if available, in the ENGINES section for complete overhaul procedures and specifications for the vehicle being repaired.
Remove rocker arms. Mark push rods for location. Remove push rods. Push rods can be steel or aluminum, solid or hollow. Hollow push rods must be internally cleaned to ensure oil passage to rocker arms is cleaned.
Check push rods for damage, such as loose ends on steel tipped aluminum types.
Check push rod for straightness. Roll push rod on a flat surface. Using feeler gauge, check clearance at center.
Replace push rod if bent. The push rod can also be supported at each end and rotated. A dial indicator is used to detect a bent area in the push rod.
Lubricate ends of push rod and install push rod in original location. Ensure push rod is properly seated in lifter.
Install rocker arm. Tighten bolts to specification. Adjust valves if required. See VALVE ADJUSTMENT.