Engine mounts

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Issues - Engine Mounts

Many Mercedes-Benz owners experience vibrations through the interior of the car, the steering wheel and the seat which is the first sign that your engine mounts are failing or have failed.

BenzWorld Member zz4x4 reported that he had the very common "shaking at idle" issue so he decided to replace the engine mounts. It totally solved the problem! The car was smooth once again. The job went pretty smoothly and took about three hours total time.

Other M-B owners have reported having a smooth idle until you put the car into gear, then a vibration is noticed.

Diagnosis - Engine Mounts

Diagnose failed engine mounts by following these steps;

  • Park the car with the front pointing in a "SAFE" direction, ie with no one in front and a considerable distance from objects.
  • Open the hood.
  • Have someone apply the service AND foot brakes.
  • Stand in a position to the side of the car such that you can observe the engine movement. Do not stand in front of the car.
  • Ask the Helper to gently "REV" the engine on and off.
  • Observe how much rotational rolling movement there is in the engine.
  • Decide if the amount of engine movement is excessive. You will know what "excessive" is. If the engine was Rocking and Rolling SEVERAL inches up and down you have BAD ENGINE MOUNTS!

DIY Replace - Engine Mount Front

Tips - Engine Mount Front

  • WIS specifies removing the ENTIRE Engine Mount, both the engine mount AND the portion that connects it to the engine block. This worked fine on the RIGHT mount, but on the LEFT, a hose prevented taking the mount out/or installing, in one piece. This required a combination "Bottom-Side" and "Top-Side" approach.
  • Caution; when you turn the left engine mount over to remove the mount-to-bracket bolt, be careful of the fluid in the mount. If the rubber has deteriorated badly, when the mount is flipped over, the fluid can pour onto your face.
  • Even though genuine M-B mounts are expensive, the general opinion is to NOT buy aftermarket brands.
  • The original mounts on the Mercedes-Benz are made by Lemforder.
  • If a vehicle lift is not available, put the car up on jack stands and remove the front wheels for better access under the car.
  • Have a hydraulic jack available to support the engine and to lift it slightly during the replacement procedure.
  • Disconnect the battery before starting as you do not want to short out the starter motor connection etc.
  • Before you start purchase a long 40mm length M8 x 1.25 bolt to be used as an alignment tool. During the procedure you will be lifting the engine slightly after releasing both engine mount bolts. If you do not want to remove both engine mounts simultaneously in order to keep the engine perfectly aligned, thread the 40mm bolt into the bottom right side mount hole 2-3 turns. This allows the right side to stay aligned while lifting the engine and replacing the left side mount.

Method A - Engine Mount Front

http://www.benzworld.org/forums/showthread.php?t=1388342

Method B - Engine Mount Front

These instructions apply to Mercedes-Benz cars with the V6 and V8 engine.

http://www.mercedesmedic.com/diy-engine-mount-replacement-with-pictures-video-mercedes-benz/

DIY Replace - Engine Mount Rear/Transmission

A Rear Engine and Transmission Mount DIY replace is a super easy job. It actually takes more time to get the car lifted, as it does to R/R the mount, plus, as opposed to the "expensive" front mounts, the Rear is a measly $30 bucks.

Tips - Engine Mount Rear/Transmission

  • One suggested "variation" from the WIS technique is to not REMOVE the cross-member. You can loosen it sufficiently to get the mount in/out if you minimally (1 or 2 cm) raise the transmission pan.


Special Tool - Engine Mounts

A special M-B offset wrench/spanner is available to assist with replacing M-B engine mounts. See [1]

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