Reworking valve seats - Audi MB/1B/MC-2 engines

Note - only rework the valve seats enough to produce a perfect contact pattern. Before reworking commences, calculate the maximum reworking dimension.

If the dimension is exceeded, correct functioning fo the hydraulic tappet cannot be guaranteed and the cylinder head must be renewed.

Calculating maximum permissible reworking dimension:

• Insert the valve and press it tightly against the valve seat
• Measure the distance - a - between the valve stem tip and the upper edge of the cylinder head
• Calculate maximum reworking dimension from the measured value and the minimum dimension
• Minimum dimensions:
  • Inlet valve: 34.0 mm
  • Exhaust valve: 34.3 mm
• Measured value -a- minus minimum dimension gives the maximum permissible reworking dimension -b*-