speculations exist , when noises come out of the motor, which are not a daily.
Even a rattle in the upper area of the motor occurs very often.
1. The valve play must be
adjusted. (light to medium noise, `tickern` )
2. The camshaft
bearing of the cylinder head has got abrasions.
is worn out.
4. The camshaft
drive chain is worn out or its tension is incorrect ( in consequence of
a defective camshaft drive chain
tensioner). ( medium noise of rattle and hammer )
shafts have too much play.