Hydraulic valve lifters, checking

NOTE:

Replace malfunctioning lifters completely (lifters cannot be adjusted or repaired).
When new lifters have been installed the engine must not be started for about 30 minutes (otherwise valves will strike pistons).
Irregular valve noises when starting engine are normal.

Start engine and run until coolant temperature reaches approx. 80° C.
Increase engine speed to about 2500 RPM for approx. 2 minutes: if necessary, perform road test.

If the hydraulic lifters are still noisy, locate malfunctioning lifters as follows:

Remove cylinder head cover.
Rotate crankshaft clockwise by turning securing bolt for toothed belt sprocket until cams of lifters to be checked are pointing upward.
Measure clearance between cam and lifter.
Push lifter down with a wooden or plastic wedge. If a 0.20 mm feeler gauge can then be inserted between camshaft and lifter, replace lifter if necessary: removing and installing camshafts and camshaft adjuster. See CAMSHAFTS AND CAMSHAFT ADJUSTERS, REMOVING AND INSTALLING .

Fig 1: Pushing Lifter Down With A Wooden Or Plastic Wedge

Courtesy of AUDI OF AMERICA, INC.

NOTE: If irregular valve noise occurs repeatedly during short journeys and disappears after extended driving, the oil check valves must be replaced. See OIL CHECK VALVES, REPLACING .