| Special tools and workshop equipment required |
| t
| Valve seat re-facing tool |
Note | t
| When repairing engines with non airtight valves, it is not enough to reface or to replace the valve seats and the valves. Particularly on high mileage engines, it is necessary also to check valve guides for wear → Chapter. |
| t
| The valve seats should only be reworked just enough to produce a good seating pattern. Before re-facing, the max. allowable re-facing value must be calculated. If the reworking dimension is exceeded, the hydraulic valve clearance compensation can no longer be guaranteed and the cylinder head must be renewed. |
| The max. permissible reworking dimension is calculated as follows: |
| –
| Insert valve and press firmly against valve seat. |
Note | If the valve is to be renewed as part of a repair, use a new valve for the calculation. |
|
|
|
