A1EK

Hi Guys

I recently have been getting a little engine rattle around 65mph. I have a CLK 230K and it sounds like its a heat shield in the engine or something, however its strange how its only when I reach 65 mph and I do not get the noise at slower speeds over bumps etc?

I also thought it could be more serious, something around the supercharger? or vent flap? has anyone had a rattle like this?

A1EK

I found that the rattle is actually just at a certain revs not speed, around 2300rpm. I was thinking perhaps the belt tensioner?

beefstallionAMG

If its a heat shield, put the car on a lift and start tapping with a rubber mallet. Its difficult to diagnose over the internet. There is a multitude of things that could rattle on a W208.

Start with the exhaust, gently tap oil pan, suspension components until you find the rattle. The majority of exhaust heat shields do not serve a purpose other than to idiot proof a car parked in tall grass or over leaves. If there's nothing delicate by the rattling heat shield, the simplest fix would be to pull it off.

You could have a suspension component rattling also. Lift the car and check the wheels for vertical and horizontal play. Simple overlooked suspension rattles could be loose steering gear bolts, or wheel bearings out of spec that need tightening.

beefstallionAMG

Check your serpentine belts for cracks. Inspect the crankshaft pulley and accessory pulleys. Typically problems with a belt would cause a squeak not a rattle and would be fixed with belt dressing if the components check out.