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Cylinder head, valve gear -> 2.8 Reworking valve seats for Your Volkswagen Touareg SUV First Generation (2002-2010)

Touareg 2003 ➤  
8-cylinder injection engine - Edition 11.2011  
♦ Universal dial gauge bracket -VW 387-  
♦ Dial gauge  
Test procedure  
– Insert new valve into guide. The end of the valve stem must  
be flush with the guide. On account of differing stem diame‐  
ters, only use inlet valve in inlet guide and exhaust valve in  
exhaust guide.  
– Determine rock. Wear limit: 0.8 mm  
lk  
If rock tolerance is exceeded:  
– Renew cylinder head.  
2.8  
Reworking valve seats  
Special tools and workshop equipment required  
♦ Depth gauge  
♦ Valve seat refacing tool  
Procedure  
Note  
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 ⇒ page 65 .  
Valve seats are only to be reworked to the extent required to  
yield a proper surface appearance. Before beginning to rework  
valve seats, calculate the maximum permissible reworking di‐  
mensions. If the reworking dimension is exceeded, the hy‐  
draulic valve clearance compensation can no longer be  
guaranteed and the cylinder head must be renewed.  
– Remove camshafts ⇒ page 56 .  
The max. permissible reworking dimension is calculated as fol‐  
lows:  
– Insert valve and press firmly against seat.  
66  
Rep. gr.15 - Cylinder head, valve gear  
Touareg 2003 ➤  
8-cylinder injection engine - Edition 11.2011  
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 minimumlkdimension.  
Minimum dimension:  
Inlet valves (outer)  
Inlet valve (centre)  
Exhaust valves  
mm  
mm  
mm  
34.0  
33.7  
34.4  
Measured distance -a- minus minimum dimension = maximum  
permissible reworking dimension.  
Example:  
Measured distance  
Minimum dimension  
Max. permissible reworking dimension  
34.4 mm  
34.0 mm  
0.4 mm  
=
Note  
If the max. permissible reworking dimension is 0 mm or below 0  
mm, repeat measurement using new valves. If the result does not  
change renew cylinder head.  
Reworking valve seats  
Reworking inlet valve seat  
a - = ∅ 26.2 mm  
b - = 1.5…1.8 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 - = ∅ 29.0 mm  
b - = approx. 1.8 mm  
Z - = bottom surface of cylinder head  
α - 45° valve seat angle  
β - 30° upper correction angle  
γ - 60° lower correction angle  
2. Repairing valve gear  
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