Rattle from under vehicle

[Gazza120665]

Hi everybody. Just joined mb club and hoping that someone can help me. I've got a c180k w204 on a 2004 plate with quite low mileage for its age. Runs like a dream but since it's mot in may, i keep getting a rattling noise from beneath the car around the mid section. No rattling on start up from cold or while driving. Only seems to occur when the car is started up after being driven for a while. Only way to describe the noise is its a rattle with a sort of "air escaping" sound. Louder vibration when engaging gear. The garage that did the mot spent 2 hours checking it over. Even though the noise didn't occur at the time, they couldn't find any faults with the car. No lodd of power at all. Please help. Its doing my head in. Thanks in advance.

 

[A.J.]

Hi Gazza120665, welcome to the forum. Is that a loose exhaust you are hearing like a broken exhaust bracket or something similar ?. By the way your C180 is a W203 not a W204.

 

[LostKiwi]

It could possibly be heatshields come loose or a baffle breaking up in the centre box. As the exhaust heats up the noise will stop as the metal expands to fill the gap.

 

[Gazza120665]

Hi ADJ & LostKiwi.
Thank you both for a prompt reply. I shall have a look at those items that have both mentioned. Much appreciated.

 

[Gazza120665]

Hi ADJ.
The noise is more of a vibration rattle than a loose bracket. I'm not sure it's a bracket issue as the garage have checked all connections and couldn't find any faults. What I can't understand is the sort of air popping noise as I engage drive or reverse. It definitely sounds like something to do with the exhaust system though.