Subaru Outback 2010 idling very loudly

My car has been in at Subaru for a month as well as at my mechanic a Subaru specialist and they have not been able to determine the cause.. They have put in on the computer and no issues have been detected. They have also checked the
Air filter housing, inspected for bulletins,inspected vacuum hoses, removed the DPF, no blockages,inspected inter cooler, inspected EGR valve- blocked the EGR valve from manifold and the vehicle still had the noise present, inspected the throttle cable, ultilised chassis ears, removed intake valve to view cracks all good, sent FPRS to Subaru- were unsuccessful in determining cause.

Has anyone else experienced this issue or have any suggestions. Subaru's next suggestion is to remove the engine and inspect the valve clearance

G'day & Welcome Verity J.

Diesels can be a bit "clackity clack", my Triton sounds like a barrel of loose bolts and nuts when it starts up. As the vehicle is 7 YO I guess things could be loosening up a little. Does it really sound any worse than other diesels?