Rocker Arm & Valve Lash Adjuster: Inspection

NOTE: Ensure valve lash adjusters are kept clean. DO NOT disassemble valve lash adjusters. Use clean diesel fuel only for cleaning valve lash adjusters.

NOTE: Use of Lash Adjuster Retainer (MD998441) helps facilitate valve lash adjuster air bleeding.

Immerse valve lash adjuster in clean diesel fuel. While lightly pushing down inner steel ball using Air Bleed Wire (MD998442), move plunger up and down 4-5 times to bleed air. See Figure. Remove air bleed wire and press plunger. If plunger is hard to push in, lash adjuster is normal. If plunger can easily be pushed in until it bottoms out, bleed valve lash adjuster again and retest. If after bleeding, valve lash adjuster can still be depressed easily, replace valve lash adjuster.
After completing air bleeding, hold valve lash adjuster upright to prevent diesel fuel from leaking out. Place valve lash adjuster in to Leak-Down Tester (MD998400). After plunger has gone down .008-.020" (0.2-0.5 mm), measure time taken for plunger to lower .04" (1 mm). See Figure. With diesel fuel at 59-68°F (15-20°C), it should take 4-20 seconds for plunger to lower .04" (1 mm). Replace as necessary.