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Valve dimensions > < Renewing valve stem oil seals with cylinder head removed

A3 Mk2

Checking hydraulic bucket tappets
Checking hydraulic bucket tappets
  Note
t  The hydraulic bucket tappets cannot be serviced.
t  Irregular valve noises when starting engine are normal.
Special tools and workshop equipment required
t  Feeler gauge
t  Wooden/plastic wedge
Procedure
–  Start engine and let it run until the radiator fan has switched on once.
–  Increase engine speed to about 2500 rpm for approx. 2 minutes; perform test drive if necessary.
  Note
If the irregular valve noise stops but repeatedly re-occurs when driving short distances, then the oil retention valve is defective. Fitting location: in oil filter bracket → Item. The oil retention valve cannot be renewed separately.
If the hydraulic tappets are still noisy, locate defective tappet as follows:
–  Remove cylinder head cover → Chapter.
–  Turn crankshaft until cam of bucket tappet to be tested is at top:
t  Vehicles with manual gearbox: push vehicle forwards with 4th gear engaged and ignition switched off.
t  Vehicles with dual clutch gearbox: remove centre noise insulation and rotate crankshaft in clockwise direction via crankshaft sprocket central bolt.
   
–  Determine clearance between cam and bucket tappet:
–  Use wooden or plastic wedge to press down bucket tappet.
If it is possible to insert a feeler gauge of 0.20 mm between camshaft and bucket tappet:
–  Renew hydraulic bucket tappet → Chapter „Removing and installing camshaft“.
  Note
t  After installing the camshaft, the engine must NOT be started for about 30 minutes. The hydraulic tappets have to settle (otherwise valves will strike pistons).
t  After working on the valve gear, turn the engine carefully at least 2 rotations to ensure that none of the valves make contact when the starter is operated.
  A15-0529

Valve dimensions > < Renewing valve stem oil seals with cylinder head removed