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Valve guide seal: replacing > < Valve dimensions

Leon Mk2

Valve seats
Valve seats
–  The valve seats should only be reworked just enough to produce a perfect contact surface in the valve.
When repairing engines with leaking valves, it is not sufficient to rectify or renew valve seats and valves; it is important to check the wear on the guides.
Before reworking, the maximum permissible oversize measurement is calculated. If this measurement is surpassed, the correct functioning of the valve clearance compensation is not guaranteed, and the cylinder head must be replaced.
   
To calculate the maximum permissible oversize measurement, insert the valve and press it firmly against its seat (if the valve is replaced during repair, use a new valve for measuring).
–  Measure the separation “a” between end of valve stem and upper edge of cylinder head.
The maximum oversize measurement is the value which results from subtracting value ·“a” the value of the minimum measurement shown in the table below:
Minimum measurement:
Inlet valve 35.80 mm
Exhaust valve 36.10 mm
  V15-0640
Reworking of inlet valve seat
a - Ø 35.7 mm.
b - 1.6 mm
45° - Valve seat angle
  Note!
The angling of 30° of the valve seat is compulsory due to the flow situation in the intake ports.
  V15-0863
Reworking of the exhaust valve seat
a - = Ø 31.4 mm.
b - = 2.7 mm
45° - = Valve seat angle
  V15-0864

Valve guide seal: replacing > < Valve dimensions