Rocker Arm Assembly: Testing and Inspection

LASH ADJUSTER 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 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.

POSSIBLE NOISE SOURCES
Spongy/soft/aerated lash adjusters.
Missing lash adjuster swivel contact pads.
Intake rocker-to-camshaft bearing journal contact.
Rocker arm bind-up.
Intake rocker arm-to-spark plug tube contact.
Excessive cam end play.
Broken valve spring.
Broken/loose camshaft sprocket bolt.
Incomplete cam lobe machining.
Cracked lash adjuster cartridge body.

POSSIBLE NOISE MISDIAGNOSIS SOURCES
SRV valve axle chatter.
Exhaust rocker arm-to-cylinder head cover contact.
Piston pin bore fit.
Timing drive hydraulic tensioner tick.
Accessory drive belt deterioration.
Piston-to-bore clearance knock.
Crankshaft bearing noise.





LASH ADJUSTER (TAPPET) NOISE CHART