Volkswagen Workshop Service and Repair Manuals

Reworking valve seats (engine codes BFH, BJS, BML) Special tools and workshop equipment required t  Depth gauge t  Valve seat refacing tool Procedure   Note t  When repairing engines with leaking valves, it is not sufficient to rework or renew valve seats and valves. Particularly on high mileage engines, it is necessary also to check valve guides for wear → Chapter. t  Valve seats should be reworked only enough to produce a perfect seating pattern. 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. –  Remove camshafts → Chapter. The max. permissible reworking dimension is calculated as follows: –  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:

Short inlet valve	mm	31.8
Long inlet valve	mm	10.2
Short exhaust valve	mm	31.8
Long exhaust valve	mm	10.2

Measured distance -a- minus minimum dimension = maximum permissible reworking dimension. Example:

	Measured distance	10.6 mm
—	Minimum dimension	10.2 mm
=	Max. permissible reworking dimension	0.4 mm

Reworking inlet valve seat a -  = Ø 32.8 mm b -  = max. permissible reworking dimension c -  = 0.9…1.5 mm d -  = max. Ø 38.0 mm r2 -  = radius 2.0 mm Z -  = bottom surface of cylinder head α -  45° valve seat angle β -  30° upper correction angle γ -  60° lower correction angle

Reworking exhaust valve seat a -  = Ø 29.8mm b -  = max. permissible reworking dimension c -  = 1.2…1.7 mm d -  = max. Ø 35.0 mm r2 -  = radius 2.0 mm Z -  = bottom surface of cylinder head α -  45° valve seat angle β -  30° upper correction angle γ -  60° lower correction angle

Valve dimensions for engine codes BFH, BJS and BML   Note Valves must not be reworked. Only lapping-in is permitted. Dimensions of inlet valves

Dimension		Short inlet valve	Long inlet valve
Ø a	mm	33.20	33.20
Ø b	mm	5.98	5.98
c	mm	102.46	136.36
α	∠°	44°40´	44°40´

Dimensions of exhaust valves

Dimension		Short exhaust valve	Long exhaust valve
Ø a	mm	30.20	30.20
Ø b	mm	5.97	5.97
c	mm	102.20	136.20
α	∠°	44°40´	44°40´