Diesel engines equipped with hardened valves (pic. 190). They can be recognized by the three grooves at the end of the rod. The design of crackers has also been changed (they have three protrusions on the inner surface) and upper spring plate (marked with yellow paint). The valves in a turbocharged engine have a special design.
In an engine with hydraulic tappets, the valves are shorter. This should be taken into account when replacing valves. Minor damage to the seat face can be repaired by lapping the seat face against the valve seat face as described above.
Check main valve dimensions (pic. 191), paying attention to the difference between intake and exhaust valves. Valves that do not correspond to the data given in table. 3 needs to be replaced. If the end of the valve stem is worn, it can be ground, removing no more than 0.5 mm of material.
The intake valve disc may be ground, provided that the size «G» (pic. 191) will not decrease by more than 0.50 mm.
Exhaust valves cannot be ground as they are made of a special material. Valve repair may include only lapping of its working chamfer or replacement.
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