Clonking sound out of SR18DE

[Ka-Bluey]

Hey guys hows things?
I've been looking at my sisters N14 GTI hatch and there is a clonking sound coming out of the engine when its idleing (whether in D or N or P). I put a screwdrive up agains the rocker cover and can hear loud clonking inside around the timing chain area, its not constant maybe every 2 second it would clunk for about 1 second and so on.
Does anyone have any idea what it could be?
Im gonna take the cover off tomorrow and have a look, just wanted to see if anyone knows what it could be.

Thanks, very urgent.

[Ka-Bluey]

Problem resolved, with further investigations and more listening with the screwdriver i found out that the alternator is busted up inside.

Mods, can delete this post.