In our 2000 Mercedes E320, we keep hearing noises. When we accelerate we hear like a light chain noise. Like when you ride a bicycle, and stop moving the pedals, you hear that noise coming from the chains. Its sounds like that. Then when it is at low RPM, we hear a distant ''rocks in a can'' noise. What could be wrong? The gas mileage is a little lower than usual too. The oil has been changed so l do not think it is that. Does it need a tune up? What do we do???

Take it to your Mercedes dealer. It is trying to tell you that it needs some of Mercedes' very expensive TLC. lol

Is this sound more noticeable if you are outside and the car drives by? Some E-Class around this age start exhibiting rattling catalytic converter problems. If one or both of the catalysts are starting to break apart, that could also explain the drop in fuel mileage.

Take it to the dealer,,,,,,,,the ''rocks in a can'' noise is likely to be a bad catalytic converter, it is covered under warranty for 8 years/80,000 miles. The change in fuel economy could also be caused by converter issues, but may also be a faulty sensor on the engine. The dealership service tech can do a ''short test'' to check all of the electrical systems on the vehicle.

If over 200,000 miles,its due for a timing chain.

sounds like a chain huh. Ur probably right could be the timing chain. Its a lil costly. Take it in immediately.

Look at the exhaust system. Might be something loose in there.

Have the timing chain checked too.