When the valve stem is pushed in from above, this may be due to age, but often due to poor hardness of the valve or adjusting bolt. These parts must have the same hardness, which is of course the original case, but if one of these parts has been replaced by another quality, this can cause problems, resulting in broken valve stems. To be sure, install valve stem caps that protect the valve stem. You may need to replace the adjusting bolts rather than disassemble your engine to replace the valves.
The use of valve stem caps changes the geometry of the valve and will need to be repaired by placing adjustment plates under the rocker shaft (see Options tab).
These hardened valve stem caps are suitable for valves with a top of 8 mm. Valves with a 9 mm stem also have an 8 mm top and are therefore also suitable for these caps.
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