Hello again Andy -
Thank you for that --that is all helpful.
What you will need to to with this Andy is narrow the noise down fully - To do that have the engine running and use a screwdriver - as a stethoscope.. One in placed firm in your ear to get the best sound - then place the other end on various parts of the engine... when you hit on the area where the fault is / noise is emanating from - the noise will be accentuated in your ear. Just be careful with the belt and pulleys rotating of course - but thats the way to do this.
If you find the noise is accentuated from the timing area - then yes, it will be a worn chain.. and I suspect it will be to be honest - but this is the way to be sure. Replacement of the chain assembly is the only answer to that then.
The other thing that these are known for is DMF trouble / failure - flywheel .. when these are on the way out, they will cause a rattling noise - and as noises "travel" and can be confusing - thats why I said to check as above..
You can do the stethoscope check for this on the gearbox
bell housing - A worn DFM will often cause a vibration through the engine though so bear that in mind.
Again - it should become obvious where the fault is testing as above Andy.
Let me know how you go..and / or let me know if you need anything further on this..
~>>~~~ Meantime - Please do click on the "Exc / Ok rating" for me at this time.. "Thank you" in advance for that .
.. Note that you can get back to me anytime at all after doing the rating - it doesn't close you out --
Best Rgds, MIKE.