What are the common causes of engine noise in Audi 80?

I have noticed an unusual noise coming from the engine of my Audi 80. What are the possible reasons for this and how can I fix it?

One of the common causes of engine noise in Audi 80 is a faulty timing belt. It is recommended to have it checked and replaced if necessary by a certified mechanic.

Another reason for engine noise could be a malfunctioning valve. To fix this, it is best to take your car to a trusted mechanic for a valve adjustment or replacement.