Hydraulic Lash Adjuster Bleeding

Fig 1: Rocker Arm Positioned On Base Circle Of Camshaft

Courtesy of DAIMLERCHRYSLER CORP.

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. Ensure the rocker arm is positioned on the base circle (1) of the cam. See Fig 1. Rotate engine as necessary.
   Fig 2: Purging Air From Lash Adjuster

   Courtesy of DAIMLERCHRYSLER CORP.

   1 - SPECIAL TOOL 8351

   2 - OIL AIR RELIEF SERVICE ACCESS HOLE

   3 - ROCKER ARM ASSEMBLY

   4 - INTERNAL CHECK BALL

   5 - VALVE TIP

   6 - HYDRAULIC LASH ADJUSTER WITHIN ROCKER ARM

4. For intake rocker arm positions:
   • Adjust Special Tool 8351 (1) Release Probe's gauge pin to extend approximately 20 mm (0.787 in.). Then, carefully insert the release probe gauge pin into the lash adjuster (6) service access hole (2). See Fig 2.
     CAUTION: If probe tip (1) breaks off within the lash adjuster (6), replace the affected rocker arm (3).
   • Gently unseat lash adjuster's internal check ball (4).
   • While the internal check ball (4) is held unseated, press the rocker arm (3) into the valve tip (5), allowing the lash adjuster (6) to fully collapse. Hold this fully collapsed position for about one second or longer.
   • Slowly release the rocker arm (3), thereby allowing the lash adjuster (6) to extend, which in turn refills the high pressure chamber with non-aerated oil.
   • Remove probe to allow check ball (4) to seat.
   • Recheck for sponginess. If the lash adjuster (6) sponginess is not completely or nearly eliminated, then repeat procedure.
   • If the spongy condition cannot be removed, replace effected rocker arm(s) (3).
5. For exhaust rocker arm (3) positions:
   • Adjust Special Tool 8351 (1) Release Probe gauge pin to extend approximately 20 mm (0.787 in.). Then, using two release probes, carefully insert gauge pins into the lash adjuster service access holes. See Fig 2.
     CAUTION: If probe tip (1) breaks off within the lash adjuster (6), replace the affected rocker arm (3).
   • Gently unseat BOTH lash adjuster's internal check ball (4) at the same time.
   • While the internal check ball (4) is held unseated, press the rocker arm (6) into the valve tip, allowing the lash adjuster to fully collapse. Hold this fully collapsed position for about one second or longer.
   • Slowly release the rocker arm (3), thereby allowing the lash adjuster (6) to extend, which in turn refills the high pressure chamber with non-aerated oil.
   • Remove probes (1) to allow check balls (4) to seat.
   • Recheck for sponginess. If the lash adjuster (6) sponginess is not completely or nearly eliminated, then repeat procedure.
   • If the spongy condition cannot be removed, replace effected rocker arm(s) (3).
6. Install cylinder head cover(s).