Hydraulic Lash Adjuster

A tappet-like noise may be produced from several items. Check the following items if a tappet-like noise is present:

1. Engine oil level too high or too low. This may cause aerated oil to enter the adjusters and cause them to be spongy.
2. Insufficient running time after rebuilding the cylinder head. Low speed running up to 1 hour may be required.
3. Turn the engine off and let set for a few minutes before restarting. Repeat this several times after the engine has reached normal operating temperature.
4. Low oil pressure.
5. The variable timing system filter in cylinder head or the oil passage to the cylinder head is plugged with debris.
6. Air ingested into oil due to broken or cracked oil pump pick up.
7. Worn valve guides.
8. Rocker arm ears contacting valve spring retainer.
9. Rocker arm loose, adjuster stuck or at maximum extension and still leaves lash in the system.
10. Oil leak or excessive cam bore wear in cylinder head.
11. Faulty lash adjuster.

Lash Adjuster Inspection:

• Inspect the lash adjusters for "sponginess" while installed in the cylinder head with the camshaft at base circle. Depress the portion of the rocker arm over the adjuster. Normal adjusters should feel firm when pressed quickly. When pressed very slowly, lash adjusters should collapse.
• Remove any suspected lash adjusters, and replace.
• Before installation, verify the adjusters are full of oil. This can be verified by minimal plunger travel when lash adjuster is depressed quickly.