I have a ‘03 C320 4matic T-model with (only) 80.000 miles on it. The car runs great but there is an annoying ticking noise coming from the engine, especially when the engine is cold. It sounds like ticking with a pencil on a table. The ticking follows the rpm. When the car leans forward (e.g. on a hill) the noise fades away. I only hear it when it idles.
I thought it might be the oil level, or the wrong oil grade, but the garage says it’s not… They do hear it also, but have no idea what it could be…
any suggestions?
Thanks

 

I have 1998 SL 500R That only has 60K miles doing the same thing let me Know if you find the problem

I am thinking that it may have something to do with the exhaust system?

 

Usually ticking, especially when the engine is cold, involves the valve train. However, you can't rule out vibration (something get loose and then taps with the engine run, muffler baffles). The best way to pinpoint the location of the noise is to use a pipe (PVC) and use it just like a Dr. uses a stethoscope. You'll be able to find the source of the noise and then continue from there. Good luck.
B.E. Griffith

 

Found it!
After many garage visits, corresponding with MB specialists, etc. I finally found the reason for the annoying ticking noise. The complicating factor is that it gets worse when the car was cold, and will disappear when the car is tilted forward.
Today I went to see the local MB dealer. I didn’t have much faith when a young ‘kid’ walked back to the car with me. The ticking was barely audible because the car was warm, but he picked it up within seconds. It’s the ‘purging valve’ he said (a small unit at the driver’s side of the engine). His description of the noise it makes was an exact match…
No big deal according to him. Everyone knows what kind of noise it makes….