Valve Seats, Reworking: Procedure

WARNING: This page is about a different car, the 2014 Volkswagen Touareg, 2013 Volkswagen Touareg, 2012 Volkswagen Touareg, and 2011 Volkswagen Touareg. However, it is still accessible from the selected car via links, so may be relevant.

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 .

Only reface valve seats enough until a perfect contact pattern is obtained. 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.

-- Remove the camshafts. Refer to CAMSHAFT, 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.

-- Measure distance -a- between end of valve stem and upper edge of cylinder head.

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

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- 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 minus minimum dimension = max. permissible reworking dimension.

Example

	Measured distance	10.6	mm
-	Minimum dimension	10.2	mm
=	Maximum permissible reworking dimension	0.4	mm