Are you feeling vibrations through the seats and maybe even on the steering wheel or dash while sitting at a red stop light? Are these vibrations more noticeable when you car is in Drive or Reverse? If you answered yes, then most likely you need new engine & transmission mounts. If the vibrations intensity changes when your car is in Park or Neutral and are more noticeable in D or R then it is highly likely that your problem is the motor mounts. On most Mercedes Benz the engine mounts start to loose the fluid around the 100k mile mark and they get worse and worse after that. At first you may notice mild vibrations but they will get worse in the next 5k-10k miles.
Your car has 3 engine mounts. Two on each side of the engine and one at the end of the transmission by the output shaft.
The transmission mount is very easy to replace. You simply raise the car, support the transmission with a jack. Remove 4 or 5 bolts on the transmission mount and install new one. If you change your oil you can do this too. Here is a picture of the transmission mount, shown upside down so you can see the location of the bolts. You can get this mount for less about $20 dollars on Amazon, see here.
The two engine mounts are oil filled. Once you replace these you will think that all of the sudden you got a new car. The difference from the old mounts to the new ones is night and day. These amounts are not that easy to replace. Well, if you don’t have the right tools that is. If you have the Mercedes Benz tool for engine mounts than this is an easy job as well. You will need this engine mount tool which you can get on Amazon here for just a few bucks and it’s definitely worth it.
The two engine mounts can range from $50-$100 per set. You can get quality ones, like these ones, on Amazon for a fraction of dealer prices. Here are a few quality oil filled mounts on Amazon. Here is a picture of the two mounts.
Here is a bad engine mount from an E Class that needed replacement. The owner of this car had never replaced them and the car had 140k miles at this point. The interior vibrations were very intense. Once these mounts were replaced, you thought the car had just come out of the factory when you sat inside. The mount split in half and all of the fluid came out, look at the picture and compare it with the new ones above.
We have replaced a lot of these mounts and soon will do a DIY article on how to replace them. The labor on replacing all the three mounts should not be more than 3-4 hours. If your mechanic is charging you more hours than that, he doesn’t have the right tools for the job.
Here is another way you can confirm that your engine mounts are bad. Be careful as you perform this procedure.