Saab: saab 9.3SE 2,3 TURBO, engine knocking

Question
my engine has started knocking and is quite noisy, it still starts and is driveable, have you any idea whatb it could be, someone has suggested the timing chain ?

Answer
Steve:
 The knocking you experience can come from a number of sources, some more serious than others. To pin it down require some specifics such as:
a. Does the knocking speed up as the engine does?
b. Does the knocking occur at all engine temperatures, or only when hot, only when cold?
c. Does the knocking intensify with engine loading?
d. Was there any specific circumstance that immediately preceded/caused the knocking?
e. How many miles are on the engine?

 Typical timing chain noises are more like "rattles" since the masses involved are small as opposed to knocking which suggests larger forces/masses colliding.

 If you get back to me regarding the above and I'll be able to better answer your likely problem.

                Hope this helps,
                               Jerry