Checking Valves - Audi A8 2003 Workshop Manual

8-cylinder TDI engine (4.2 ltr. 4-valve common rail), mechanics - Edition 12.2013
♦ Dial gauge - VAS 6079-
Procedure
– Insert valve into valve guide.
• End of valve stem must be flush with valve guide.
Note
Only insert inlet valve into inlet guide and exhaust valve into ex‐
haust guide, as the stem diameters are different.
– Determine amount of sideways play.
• Wear limit for inlet and exhaust valve guide: max. 1.0 mm.
Note
If the wear limit is exceeded, repeat the measurement with
♦
new valves. Renew cylinder head if wear limit is still exceeded.
Valve guides cannot be renewed.
If the valve has to be renewed as part of a repair, use a new
♦
valve for the measurement.
3.11

Checking valves

– Visually inspect for scoring on valve stem and on seating sur‐
face.
If scoring is clearly visible:
– Renew the relevant valve.
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Audi A8 2003 ➤
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3. Servicing valve gear