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 .
LIFTERS
Hydraulic Lifters
Before replacing a hydraulic lifter for noisy operation, ensure noise is not caused by worn rocker arms or valve
tips. Also ensure sufficient oil pressure exists. Hydraulic lifters must be installed in original location. Remove
rocker arm assembly and push rod. Mark components for location. Some applications require intake manifold,
cylinder head or lifter cover removal. Remove lifter retainer plate (if used). To remove lifters, use a hydraulic
lifter remover or magnet. Different type lifters are used. See Fig. 13 .
On sticking lifters, disassemble and clean lifter. DO NOT mix lifter components or positions. Parts are select-
fitted and are not interchangeable. Inspect all components for wear. Note amount of wear in lifter body-to-
camshaft contact area. Surface must have smooth and convex contact face. If wear is apparent, carefully inspect
cam lobe.
Inspect push rod contact area and lifter body for scoring or signs of wear. If body is scored, inspect lifter bore
for damage and lack of lubrication. On roller type lifters, inspect roller for flaking, pitting, loss of needle
bearings and roughness during rotation.
Measure lifter body O.D. in several areas. Measure lifter bore I.D. Ensure components or oil clearance is within
specification. Some models offer oversize lifters. Replace lifter if damaged.
If lifter check valve is not operating, obstructions may be preventing it from closing or valve spring may be
broken. Clean or replace components as necessary.
Check plunger operation. Plunger should drop to bottom of the body by its own weight when assembled dry. If
plunger is not free, soak lifter in solvent to dissolve deposits.
Lifter leak-down test can be performed on lifter. Lifter must be filled with special test oil. New lifters contain
special test oil. Using lifter leak-down tester, perform leak-down test following manufacturer's instructions. If
leak-down time is not within specifications, replace lifter assembly.
Lifters should be soaked in clean engine oil several hours prior to installation. Coat lifter base, roller (if
equipped) and lifter body with ample amount of Molykote or camshaft lubricant. See Fig. 13 . Install lifter in
original location. Install remaining components. Valve lash adjustment is not required on most hydraulic lifters.
Preload of hydraulic lifter is automatic. Some models may require adjustment.
NOTE:
Some manufacturers require that a crankcase conditioner be added to engine
oil and engine operated for specified amount of time to aid in lifter break-in
procedure if new lifters or camshaft are installed.
1998 Chevrolet Pickup C1500
GENERAL INFORMATION Engine Overhaul Procedures