Check the key seat: it must not be damaged or worn by contact with the key.
Caution! To prevent accidental loosening that would cause serious damage to the engine, always use new self-locking ring nuts (A) for fixing all the timing pulleys.
Check that the tensioner bearings rotate freely without excessive play. The mobile tensioner bearings can be changed after removing the outer circlip (B).
When refitting the new bearings on the pin, use retaining compound. The belts must be in perfect condition; they should be changed every time the engine is overhauled.
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