Calculating maximum permissible refacing dimension
Insert valve and press it firmly against valve seat.
Fig. 225: Measuring Distance Between Valve Stem End (Upper Edge) And Top Surface Of Cylinder
Head Using Depth Gauge
Courtesy of VOLKSWAGEN UNITED STATES, INC.
Measure distance - a - between valve stem end (upper edge) and top surface of cylinder head using a
depth gauge.
Calculate max. permissible refacing dimension from measured distance and minimum dimension.
NOTE:
When repairing engines with leaking valves, it is not sufficient to reface
valve seats and replace valves. Valve guides must also be checked for
wear. This is particularly important on high mileage engines --> Valve
guides, checking.
Valve seats should only be refaced just enough to produce a perfect
seating pattern.
Calculate the maximum permissible refacing dimension before refacing.
If refacing dimension is exceeded, function of hydraulic valve lifters can
no longer be guaranteed and cylinder head should be replaced.
NOTE:
If valve is to be replaced as part of a repair, use a new valve for
calculation.
Minimum dimension
2005 Audi A4 Quattro
ENGINE 1.8 Liter 4-Cyl. 5V Turbo Engine Mechanical, Engine Code(s): AMB
1:01:07 AM Page 151
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