Lifter / Lash Adjuster: Service and Repair

HYDRAULIC LASH ADJUSTER BLEEDING

NOTE: Use this procedure to manually bleed aerated oil from the lash adjuster and remove sponginess.





1. Run the engine, bringing it to operating temperature in order to freshly pressurize and warm the valvetrain system oil supply.
2. Remove cylinder head cover(s).
3. Rotate engine until the rocker arm is positioned on the base circle of the cam (1).





4. For intake rocker arm positions:CAUTION: If probe tip breaks off within the lash adjuster, replace the affected rocker arm.

a. Adjust the gauge pin of Release Probe 8351 (1) to extend approximately 20 mm (0.787 in.). Then, carefully insert the release probe gauge pin into the lash adjuster service access hole (2).
b. Gently unseat lash adjuster's internal check ball (4).
c. While the internal check ball is held unseated, press the rocker arm (3) into the valve tip (5), allowing the hydraulic lash adjuster (6) within the rocker arm to fully collapse. Hold fully collapsed position for at least one second, or longer.
d. Slowly release the rocker arm, thereby allowing the lash adjuster to extend, which in turn refills the high pressure chamber with non-aerated oil.
e. Remove Release Probe 8351 to allow check ball to seat.
f. Recheck for sponginess. If the lash adjuster sponginess is not completely or nearly eliminated, then repeat procedure.
g. If the spongy condition cannot be removed, replace effected rocker arm(s).





5. For exhaust rocker arm positions:CAUTION: If probe tip breaks off within the lash adjuster, replace the affected rocker arm.

a. Adjust the gauge pins of two Release Probes 8351 (1) to extend approximately 20 mm (0.787 in.). Then, using the two release probes, carefully insert gauge pins into the lash adjuster service access holes (2).
b. Gently unseat BOTH lash adjuster's internal check balls (4) at the same time.
c. While the internal check balls are held unseated, press the rocker arm (3) into the valve tip (5), allowing the hydraulic lash adjuster (6) within the rocker arm to fully collapse. Hold fully collapsed position for at least one second, or longer.
d. Slowly release the rocker arm, thereby allowing the lash adjuster to extend, which in turn refills the high pressure chamber with non-aerated oil.
e. Remove the two Release Probes 8351 to allow check balls to seat.
f. Recheck for sponginess. If the lash adjuster sponginess is not completely or nearly eliminated, repeat procedure.
g. If the spongy condition cannot be removed, replace effected rocker arm(s).
6. Install the cylinder head cover(s).