rcchris7

Hi guys,

New to owning an MB. Previous have been driving a lot of GMC, Lexus, BMW but decided to purchase a very poorly maintained 2010 Mercedes C300 to save. I got the car at 149,000kms running rough, a quick look showed signs of neglect (original plugs, air filter full of leaves, brake pads worn to steel and gouging rotors.. etc.) but that car was priced appropriately, plus I enjoy turning wrenches. One issue I haven't been able to resolve is a vibration I have. It really makes the car feel like a 1990's Toyota Corolla rather than a 2010 Mercedes. It starts as soon as the car is turned on and matches the RPM whether the car is in park, neutral, or drive. Under load it is worse (going uphill while accelerating to highway speeds it shakes similar to hitting the rumble strips on the side of the highway). When the car is up to speed and I'm just maintaining speed it runs until I accelerate to pass, the vibration is back. Looking to solve this problem because I figure it will only cause more damage if I ignore it.

From everything I've read and my own knowledge I'm leaning towards the torque converter being the cause. My thinking is that this is the only part that is turning whether the car is in drive or neutral. Initially I read that it is likely the flex discs or rear transmission mount but it is repeatable when the car is in park or neutral. Other possibilities I haven't ruled out would be motor mounts, power steering pump, or even a bad idler pulley. I can post of video if you feel it would help diagnose. Looking for some insight and advice from the MB community more familiar with these cars before I start throwing parts at this car hoping it goes away.

I try to do all my own work but it sure is cold in the driveway these days - to date I've caught the car up on the following parts:

-Repaired ESL... what a pain. I changed the motor myself when it died while locked. I'd love to share some advice if anyone needs it.
-Spark Plugs
-Air Filters
-Rotors & Pads
-Fresh Oil & Filter
-Rear Struts

Parts still on route are to be installed:
-Fuel Filter
-Windshield Washer Motor
-Cabin Filter

Thanks in advance for any advice!

W204Motorsports

My guess is the Engine mounts are toast. I would also look into a transmission mount while at it.

I was wondering what was wrong with the rear shocks? Bouncy ride/leaking?

sege

Maybe consider an out of balance or worn CV joint on drive shafts

rcchris7

Right Rear shock was blown, bouncing and pulling even so I replaced the set. Is the hydraulic fluid leaking from the mounts able to be seen to diagnose the motor mounts? Wouldn't hurt to replace them anyhow. I'll order a set off RockAuto

rcchris7

If the drive shaft comes out I'll certainly get it balanced. I'll be heading under the car to look at the flex discs and I'll check the driveshaft for play while I'm under the car.