2006 GTI engine knock

[Pollywaffle]

Hi guys, I bought a 2006 MKV GTI a few weeks ago. It drives great and I really like it!
However, I've discovered this engine knock noise and was wondering if anyone could diagnose it.

Here's a short video to give you some idea:


The sound isn't there when the car kicks over and is cold, but it's there shortly after when a bit warm.
The car still drives great and doesn't seem to be suffering any performance loss.
I've plugged a Vagcom in and I get no engine error codes, except an ABS code: 01314
I've checked the cam follower. It was worn but not broken. It's been replaced with one from the dealership.
The spark plugs were black, but I've cleaned them up for now.
Oil looks fine as it had a service in July.

Could it be running too rich?
Is the cam chain loose?

Any help would really be appreciated.

[Lucas_R]

I cant watch the video at work (work blocks it) so cant comment on most of your questions at this stage.....but the engine in the Mk5 GTI has a timing belt, not a chain. So you can rule that out.

Water pumps are a common failure in the Mk5 too. I'll watch the video tonight and see if i can help further - but there are some VW trained mechanics on here who might be able to help also.

[Snail Style]

Sounds like the cam chain tensioner. The camshaft is belt driven but the intake cam is driven via a chain on the exhaust camshaft.
RE:

Not a huge job but not a one hour job also. Is the noise more so from the rear of the engine/high pressure pump area? And would you describe the sound as "diesely"? If yes to those, then most likely it's the cam chain.

[Pollywaffle]

Thanks for the replies, guys.
Yes, it certainly sounds diesely. The noise seems to be coming from the back of the engine (if you're standing and facing the car while the bonnet is open) and more towards the left. So, I guess where the chain is.
I'm not driving the car at the moment, but I'll have time on Wednesday or Thursday to investigate more.