POSSIBLE NOISE SOURCES POSSIBLE NOISE MISDIAGNOSIS SOURCES
Spongy/soft/aerated lash adjusters. SRV valve axle chatter.
Missing lash adjuster swivel contact pads. Exhaust rocker arm-to-cylinder head cover contact.
Intake rocker-to-camshaft bearing journal contact. Piston pin bore fit.
Rocker arm bind-up. Timing drive hydraulic tensioner tick.
Intake rocker arm-to-spark plug tube contact. Accessory drive belt deterioration.
Excessive cam end play. Piston-to-bore clearance knock.
Broken valve spring. Crankshaft bearing noise.
Broken/loose camshaft sprocket bolt.
Incomplete cam lobe machining.
Cracked lash adjuster cartridge body.
LASH ADJUSTER (TAPPET) NOISE CHART
POSSIBLE CAUSES CORRECTION
1. Engine oil level—too high or too low. This may
cause aerated oil to enter the adjusters and
cause them to be spongy.
1. Check and correct engine oil level.
2. Insufficient running time after rebuilding
cylinder head.
2. Low speed running of up to 1 hour may be required to fully
evacuate trapped air from the valve train system. During this
time, turn engine off and let set for a few minutes before
restarting. Repeat this several times after engine has
reached normal operating temperature.
3. Air trapped in lash adjuster (after 1 hour run
time).
3. See below:
(a) Check lash adjusters for sponginess while installed in
cylinder head. Depress part of rocker arm over adjuster.
Normal adjusters should feel very firm. Very spongy adjusters
can be bottomed out easily.
(b) Before proceeding, perform Lash Adjuster Bleeding
procedure.
(c) If lash adjuster(s) are still spongy, replace with new
adjuster/rocker arm assembly*.
4. Low oil pressure 4. See below:
(a) Check and correct engine oil level.
(b) Check engine oil pressure.
(c) Check for excessive bearing clearance and correct.
(d) Check for worn oil pump.
5. Oil passage to cylinder head(s) plugged with
debris.
5. Check cylinder head oil passages and cylinder head
gasket restrictor for blockage. Clean or replace as necessary.
6. Worn valve guide(s). 6. Ream guide(s) and replace valve(s) with oversize valves
and seal(s).
7. Air injested into oil due to broken or cracked oil
pump pickup tube.
7. Inspect pickup tube and replace as necessary.
8. Collapsed lash adjuster due to debris injestion. 8. Clean debris from engine and replace lash adjuster/rocker
assembly*.
9. Intake rocker arm roller clevis ear(s) contacting
camshaft bearing journal(s) on side.
9. Inspect camshaft end play and all valve train components
for wear. Replace as necessary.
*Lash adjusters are serviced with the rocker arms—do not disassemble.
9 - 120 ENGINE 3.5L LH
ROCKER ARM / ADJUSTER ASSEMBLY (Continued)
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