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Valve guides: verification > < Camshafts: checking axial clearance

Leon Mk2

Valve seats: Reworking
Valve seats: Reworking
Special tools and workshop equipment required
   
t  Ruler -T40100-
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.
  W00-10297
–  Measure distance between end of valve stem and upper edge of the measuring guage -T40100-.
–  Calculate maximum permissible machining dimension from measured distance and minimum dimension.
Highest dimension: Inlet valve 1.0 mm, Outlet valve 0.9 mm
Maximum dimension minus measured distance of the valve protrusion = max. permissible reworking dimension.
  Note
Material thickness measuring ruler -T40100- = 7.7 mm.
Example for intake valve:
   Material thickness -T40100- - measured protrusion = valve protrusion dimension
   7.7 mm - 7.2 mm = 0.5 mm
   Maximum inlet valve dimension - valve protrusion = max. permissible machining dimension.
   1.0 mm - 0.5 mm = 0.5 mm → Remark
Max. permissible reworking dimension of the inlet valve = 0.5 mm
1)  The maximum permissible reworking dimension is shown on illustrations as dimension „b“ .
  N15-10641
Reworking the intake valve seat
  N15-0096
a
b
c
Z
α
β
γ		= Ø 34.8 mm
= maximum permitted reworking dimension1
= 1.3 - 1.9 mm
= cylinder head lower edge
= 45° valve seat angle
= 30° upper correction angle
= 70° lower correction angle

2)  Calculating maximum permissible reworking dimension → Chapter
Reworking the exhaust valve seat
   
a
b
c
Z
α
β
γ		= Ø 29.0 mm
= maximum permitted reworking dimension1
= 1.9 - 2.0 mm
= cylinder head lower edge
= 45° valve seat angle
= 30° upper correction angle
= 70° lower correction angle

3)  Calculating maximum permissible reworking dimension → Chapter
   

Valve guides: verification > < Camshafts: checking axial clearance