Valve Dimensions; Machining Valve Seats; Checking Valve Guides - Audi A8 2003 Workshop Manual

Audi A8 2003 ➤
8-cylinder TDI engine (4.2 ltr. 4-valve common rail), mechanics - Edition 12.2013
– Remove relevant cylinder head cover
– Rotate crankshaft until cam of hydraulic compensation ele‐
ment to be checked faces upwards (rotate crankshaft clock‐
wise via central bolt for vibration damper).
– Determine clearance between cam and roller rocker finger.
– Press roller rocker finger down -arrow- using a screwdriver.
If it is possible to insert a feeler gauge of 0.20 mm between cam‐
shaft and roller rocker finger:
– Renew hydraulic compensation element
⇒ "3.4 Removing and installing camshafts", page 167
3.8

Valve dimensions

Note
Inlet and exhaust valves must not be machined. Only grinding-in
is permitted.
Dimension
∅ a mm
∅ b mm
c mm
α ∠°
3.9

Machining valve seats

Note
Valve seats may not be machined due to the very small toleran‐
ces.
3.10

Checking valve guides

Special tools and workshop equipment required
♦ Universal dial gauge bracket - VW 387-
180
Rep. gr.15 - Cylinder head, valve gear
⇒ page 155
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Inlet valve Exhaust valve
28.60 ... 28.80 26.70 ... 26.90
5.968 ... 5.982 5.958 ... 5.972
97.25 ... 97.45 97.35 ... 97.55
45
.
.
45