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Reworking inlet valve seat > < Valve timing at 1 mm valve lift

Golf Mk3

Reworking valve seats
Reworking valve seats
  Note
t  When repairing engines with leaking valves, it is not sufficient to rework or renew valve seats and valves. There is also a requirement to check the valve guides for wear. This is particularly important on high mileage engines.
t  Valve seats are only to be reworked to the extent required to yield a proper surface appearance. Before beginning to rework valve seats, calculate the maximum permissible reworking dimensions. If the reworking dimension is exceeded, the hydraulic valve clearance compensation can no longer be guaranteed and the cylinder head must be renewed.
Calculating maximum permissible reworking dimension
–  Insert valve and press firmly against seat.
  Note
If the valve is to be renewed as part of a repair, use a new valve for the calculation.
   
–  Measure distance -a- between end of valve stem and upper edge of cylinder head.
–  Calculate maximum permissible reworking dimension from measured distance -a- and minimum dimension.
Minimum dimension: inlet valve 33.8 mm, exhaust valve 34.1 mm
Measured distance -a- minus minimum dimension = maximum permissible reworking dimension.
Example:
  V15-0640

-		Measured distance -a-
Minimum dimension		35.1
34.4		mm
mm
=Max. permissible reworking dimension0.7mm

  Note
If the measured distance -a- is less than the minimum dimension, repeat the measurement with new valves and if necessary, use shorter valves (valve length -c- → Chapter) or renew cylinder head.
   

Reworking inlet valve seat > < Valve timing at 1 mm valve lift