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Valve stem seals: replace when cylinder head is installed > < Checking valves

Leon Mk2

Valve seats: reworking
Valve seats: reworking
Consult the equivalence table for tools and equipment according to applicability among Seat / VW / Audi / Skoda → Chapter.
Special tools and workshop equipment required
t  Gauge
t  Valve seat re-facing tool
  Note
t  When repairing engines with non airtight valves, it is not enough to reface or to replace the valve seats and the valves. The valve guides must also be checked for wear. This is particularly important on high mileage engines → Chapter.
t  The valve seats should only be reworked just enough to produce a good seating pattern. Before re-facing, the max. allowable re-facing value must be calculated. If the reworking dimension is exceeded, hydraulic valve compensation can no longer be guaranteed and the cylinder head should be renewed.
Calculate the maximum permissible reworking level as follows:
–  Insert valve and press firmly against valve seat.
  Note
If the valve is to be renewed as part of a repair, use a new valve for the calculation.
   
–  Measure distance between end of valve stem (upper edge) and top surface of cylinder head.
–  Calculate maximum permissible machining dimension from measured distance and minimum dimension.
l  Minimum dimension for intake and exhaust valve: 7.6 mm
   Measured distance minus minimum dimension = max. permissible reworking dimension.
Example:
  N15-0660
Example:
Measured distance8.0 mm
Minimum dimension– 7.6 mm
Maximum permissible reworking dimension:= 0.4 mm

  Note
t  If the calculated maximum permissible machining dimension is 0 mm or less than 0 mm, repeat the measurement with a new valve.
t  If the result is again 0 mm or less than 0 mm, renew the cylinder head.
   
Reworking the intake valve seat
Inlet valve seat:
a - Ø 28.7 mm
b - Maximum permissible reworking dimension:
c - 1.5 ... 1.8 mm
Z - Lower edge of cylinder head
α - 45° valve seating angle
β - 30° upper correction angle
γ - 60° lower correction angle
Exhaust valve seat:
a - Ø 25.0 mm
b - Maximum permissible reworking dimension:
c - approx. 1.8 mm
Z - Lower edge of cylinder head
α - 45° valve seating angle
β - 30° upper correction angle
γ - 60° lower correction angle
  Note
Calculating maximum permissible reworking dimension → Chapter.
  N15-0096

Valve stem seals: replace when cylinder head is installed > < Checking valves