Steve06

Hello,
Lately I've noticed that my 2007 CLK 350 Cabrio (A209) with automatic transmission makes a persistent rattling/ticking noise that never really goes away and that ticks faster as I drive faster. It is especially pronounced when accelerating, but also still audible when just rolling.

However, when the car is standing, set to neutral gear and I push the gas, there is no such noise at all.

I wonder if it's from the engine or some other moving part and have hoped somebody can help me identify the cause. To help with that, I have recorded an audio sample with my smartphone: http://www.show-room.org/pics/clk_rattling_noise.mp3

What do you think this is?

Many thanks in advance,
Steve

Rudeney

I can't really hear anything particular in your MP3, but I once had a ticking noice in the C240 and it was a piece of sound insulation that had curled and was contacting the drive shaft.

Steve06

Thanks for checking out the sample, you can hear it best at around the 20th second, turning up the volume of course. This is the characteristic ticking I hear all along.

It could very well be a loose piece of sound insulation, as you suggest.

Any other opinions?

dawizard

I think I hear the same thing on my ML350, just a constant tick-tick-tick-tick and I got it checked by the dealer and they (and some folks here) mentioned it was just a result of the Direct Injection engine. It is super annoying and I am still not sure if that is actually a result of direct injection or just

https://mbworld.org/forums/new-m-cla...en-idling.html

(There is another thread where people found out more issues possibly related - https://mbworld.org/forums/new-m-cla...errerid=221431)

Glyn M Ruck

Ticking in the case of DI engines is the injectors.

On M272 engines cars the most common source is the purge valve.

Steve06

Thanks to both for your input,

but I have to stress that, contrary to the videos in the threads mentioned, in my case the ticking noise in question does NOT occur when idling and standing still, only when driving.

labguy

"You got mud in your tires!"

Steve06

Good one, but tyres are brand new.

Glyn M Ruck

Then you need to check for things touching driveshaft, axles, brake related, CV joint on the rear axle, exhaust shields etc.

New tyres ~ have you changed rims? If so could be wrong length rear bolts.

Steve06

Rims are the same. Thanks for the pointers. I'm taking the car to MB next week also for some other issues and hope they quickly find the cause.

Glyn M Ruck

Should be easy to find if they can simulate it. Could even be a cracked flex disc on the propshaft.