NOTE: When repairing engines with leaky valves, it is not enough to treat or replace the valve seats and valves. Especially in engines with a long service life, it is necessary to check the valve guides for wear.
NOTE: Valve seats should only be machined to the extent necessary to achieve a flawless working surface. The maximum allowable machining allowance should be calculated before machining. If the machining allowance is exceeded, the hydraulic clearance adjustment function in the valve drive may be impaired (hydraulic compensators), which will entail replacing the cylinder head.
Calculate the maximum allowance for machining as follows:
- insert the valve into the guide and press it firmly against the seat;
NOTE: If the valve is replaced during repair, a new valve should be used for measurements.
- measure the distance A between the end of the valve stem and the top edge of the cylinder head (fig. 2.216);
- calculate the maximum allowable machining allowance based on the measured distance A and the minimum allowable dimension.
Minimum dimensions:
- Inlet valve - 43.4 mm
- Exhaust valve - 43.2 mm
Measured distance minus minimum dimension = maximum allowance for machining.
(The information is presented on the website: VWmanual.ru)
Example:
- Measured distance - 44.1 mm
- Minimum size - 43.4 mm
- Maximum allowance for processing 44.1-43.4=0.7 mm
Intake valve seat machining
a - 35.7 mm
b - 1.6 mm
45° - Valve support surface angle
NOTE: 30° milling of the valve seat is necessary due to the flow ratio in the intake port.
Exhaust valve seat machining
a - 31.4 mm
b - 2.7 mm
45° - Valve support surface angle
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