Hi folks,

Hoping for a friendly steer on this one. Just purchased a 2017 520d M-Sport touring. Almost every time I start it, after a few seconds there is a louder high pitched rumbling noise coming from the exhaust. It lasts for about 5 - 10 seconds and the stops and it does happen occasionally after that but never when driving on a long run. This is happening daily. I have attached a video which I took a few seconds after I pushed ignition from cold one morning. The car drives great but this is annoying and not something I ever experienced with a 2015 520d I owned up to a few years ago. I have it booked into a local garage next week.

Hi Neville

Sounds as though something is loose in the exhaust a baffle may be

Hope the garage can sort it 

Dave

Thanks, just thought it odd that it only lasts for a a few seconds at a time, hopefully the garage can resolve and nothing too serious. I did see a topic from a few years ago pointing towards DPF regens but no-one seemed to find a solution to those noise issues.

Morning Neville

When a Regen is occurring the engine has to have reached a high operating temp so doubtful at start up

Dave

Thanks again

Folks, this turned out to be the compressor starting up as there is an issue with the air suspension.

All fixed now ?

Booked in early Jan under warranty so fingers crossed, compressor and two bags required apparently. 

Warranty garage having great difficulty finding any 'damaged' part or air leak so therefore I may have a fight on my hands to get anything replaced under warranty.