Valve seats, reworking

WARNING: This page is about a different car, the 2004 Volkswagen R32. However, it is still accessible from the selected car via links, so may be relevant.

Special tools, testers and auxiliary items required

Depth gauge
Valve seat refacing tool

Work procedure

NOTE:

When repairing engines with leaking valves, it is not sufficient to rework or replace valve seats and valves. It is also necessary to check the valve guides for wear. This is particularly important on high mileage engines, refer to Valve guides, checking .
The valve seats should only be reworked just enough to produce a perfect seating pattern. The maximum permissible reworking dimension must be calculated before work is carried out. If the reworking dimension is exceeded, the function of the hydraulic lifters can no longer be guaranteed and therefore the cylinder head should be replaced.

Removing camshafts, refer to Camshafts, removing and installing .

Maximum permitted refacing dimension is calculated as follows:

Insert valve and press firmly against seat.

NOTE:

If the valve is to be replaced as part of a repair, use a new valve for the calculation.

Fig 1: Identifying Distance Between End Of Valve Stem And Upper Edge Of Cylinder Head

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Measure distance - a - between end of valve stem and upper edge of cylinder head.
Calculate max. permissible reworking dimension from measured distance - a - and minimum dimension.

Minimum dimensions:

Short intake valve	mm	31.8
Long intake valve	mm	10.2
Short exhaust valve	mm	31.8
Long exhaust valve	mm	10.2

Measured distance - a - minus minimum dimension = max. permissible refaced dimension.

Example:

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

Fig 2: Reworking Intake Valve Seat

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Reworking intake valve seat

a - = 30.6 mm

b - = Max. permissible reworking dimension*

c - = 0.9 to 1.5 mm

d - = max. dia. 35.0 mm

r2 - = Radius 2.0 mm

Z - = Cylinder head lower edge

α - 45 ° valve seat angle

β - 30 ° upper correction angle

γ - 60 ° lower correction angle

Fig 3: Reworking Exhaust Valve Seat

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Reworking exhaust valve seat

a - = Dia. 26.7mm

b - = Max. permissible reworking dimension*

c - = 1.2 to 10.7 mm

d - = max. dia. 29.0 mm

r2 - = Radius 2.0 mm

Z - = Cylinder head lower edge

α - 45 ° valve seat angle

β - 30 ° upper correction angle

γ - 60 ° lower correction angle