A4 Cabriolet V6-3.0L (AVK) (2003)
Valve Seat: Service and Repair
Valve seats, refacing
Note: If a perfect pattern isn't created after hand-lapping valve seats, reface valve seats.
Special Tools and Equipment
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Depth gauge
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Valve Seat Refacing Tool
Note:
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When servicing engines with leaking valves, refacing or replacing valve seats and valves is not sufficient. It is particularly important to check
valve guides for wear on engines with higher running performance.
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Only reface valve seats enough until a perfect contact pattern is obtained.
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Before refacing, determine maximum refacing dimension.
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If refaced dimension is exceeded, hydraulic valve lifter function is no longer guaranteed and cylinder head must be replaced.
Determining maximum allowable refacing dimension
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Insert valve and press tightly against valve seat.
Note: If valve is replaced during repair, use new valve for measurement.
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Measure distance -a- between valve stem end (upper edge) and upper cylinder head surface using a depth gauge.
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Determine maximum allowable refacing dimension using distance measured and minimum dimension.
Measured distance minus minimum dimension = max permissible refaced dimension.
Note: If the maximum allowed refaced dimension is 0 mm or less than 0 mm, repeat measurement using new valve. If measurement result is still 0