Passat Sedan 4Motion W8-4.0L (BDP) (2002)
Valve Seat: Service and Repair
Valve seats, reworking
Special tools and equipment
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Depth gauge
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Valve seat refacing tool
Work sequence
Note:
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When repairing engines with leaking valves it is not sufficient to renew valve and replace valves. It is also necessary to check the valve guides for
wear. This is particularly important on high mileage engines.
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The valve seats should only be reworked just enough to produce a perfect seating pattern. The maximum permissible reworking dimension must be
calculated before work is carried out. If the reworking dimension is exceeded, the function of the hydraulic lifters can no longer be guaranteed and
therefore the cylinder head should be replaced.
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Remove camshafts.
The maximum permissible reworking dimension is calculated as follows:
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Insert valve and press firmly against seat.
Note: If the valve is to be replaced as part of a repair, use the new valve for the calculation.
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Measure distance -a- between end of valve stem and upper edge of cylinder head.
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Calculate maximum permissible reworking dimension from measured distance and minimum dimension.
Minimum dimensions:
Measured distance minus minimum dimension = maximum permissible reworking dimension.
Example:
The max. permissible reworking dimension is shown on illustrations for reworking valve seats as dimension "b".