Hi all.
im a newbie, please help.
bought a 55 plate Crossfire Coupe, but there is a loud hissing coming from the back of the engine, seemingly from under the MAF sensor.
Car drives great, no loss of powe, gear changes are smooth.
I attach a video.
Please help.

 

There are two hoses that come off the valve covers and connect at the throttle body. Check those hoses and see if wiggling the MAF sensor or Throttle body itself makes a differnce in the noise. Strange it doesn't effect driving. Check for codes.

 

Thanks for replying.

No fault codes at all. Will check the hoses in the light tomorrow

 

I plan to remove the Throttle Body tomorrow, where can I get an O Ring from please?

 

Any Mercedes dealer. Part number A 305 997 03 45 or on line. Here is one option; click

 

Brilliant, thank you