Chain noise when engine heats up
 

Hello,

I'm new in this forum and would like to ask if anyone familiar with this issue. I got a 2006 BMW E90 N46 engine. The engine sound when cold start is perfect but when it slowly heats up, there is chain noise that slowly blending in with the engine noise. The car performance is good while the engine is cold but it loses power when it is hot (~104'C but there is no engine hot warning).

However, the chain noise will go away if we rev the engine to higher rpm in park mode and it comes back once it drops to idle rpm. Any idea what could be wrong with this issue? Could it be the timing chain? I replaced the timing chain tensioner but still having the same issue.

There is no error light or sign is shown.

Thanks & Regards
Josh