Can't figure out vibration
 

I bought a 2003 CLK55 AMG (W209) with 72k miles. The car ran well, PPI had only minor problems (oil leak from one valve cover, minimal rear seal leak, etc). I'm a relatively mature driver and haven't abused the car at all. After about 1500 miles or so I noticed a vibration coming from under the right side of the transmission/passenger floor area at about 1200-2200 rpm under light acceleration. Took it to the dealer; they found loose bolts on a heat shield and engine diagnostic showed misfire but not enough to trigger CEL. Tightened and replaced bolts, got new spark plugs and wires- all 16 of them- and no more misfire. But vibration came back about 125 miles into road trip. It's a very low pitched buzz coming from under the passenger front floorboard intermittently at same rpm as before and only under light acceleration. It goes away with hard acceleration or easing off the pedal. At one point it sounded like the car was gonna apart from it but it disappeared as soon as I accelerated hard out of a corner. The car is a coupe not cab so it's not a cowl shake type of problem. Anybody here had the same problem or have any ideas?

I think it could be a few things. The CLK has a few issues that can cause vibration.

-First, if you have a warranty for it, go get the tires balanced, its a great first step and free from some places if you buy from them (discount tire!)

-Transmission Mount (cheap and easy to replace with basic skills)

-Motor Mounts (not as cheap or easy, but not terrible either)

-Driveshaft Couplings

-Worn suspension bushings

-Warped brakes (probably not tho)

-Blown strut (not as likely for vibration)

Those are at least some good places to start checking.

Vibrations on the internet are tough. Under moderate load 91ser covered most of it. You will have to climb under the car to inspect though. I found this one time.

https://cimg9.ibsrv.net/gimg/www.mbw...43a0e86acc.jpghttps://cimg9.ibsrv.net/gimg/www.mbw...43a0e86acc.jpg
You can see the gap on the carrier bearing rubber, 0.5" slop.

The only other vibration we might have missed is a bad coil pack. I replaced all of mine and many problems went away.

Cheers, Gator

re-check rear heat shield

Thanks for the suggestions but it turned out to be coolant contamination in my torque converter. So $4700 later I've got a new radiator, torque converter, and other various needed repairs/maintenance items done. The car runs/drives like a dream; it's exactly what I bought the car believing it would be. I've owned 911's, a 930, a BMW 645, and an SL500 and I have to say this is my favorite! What a great combo of blinding fast and real luxury!

Wow, you are amazing, glad you have it fixed!

post some photos of your car if you can..