A4 Quattro Wagon L4-1.8L Turbo (AEB) (1999)
Valve Seat: Service and Repair
Valve seats, refacing
Note: If a perfect contact pattern isn't obtained after hand lapping valves, 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 low compression due to leaking valves, it is not sufficient to reface or replace the valve seats and valves. It is
especially important to check valve guides for signs of wear on high mileage engines.
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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 between end of valve stem and camshaft center axis (camshaft center axis is located at the level of cylinder head upper edge).
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Determine maximum allowable refaced dimension using distance measured and minimum dimension.
Distance measured minus minimum dimension = maximum allowable refacing dimension.