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Pelican Technical Article:

Engine Mount Replacement

Nick Czerula

Time:

6 hours6 hrs

Tab:

$200

Talent:

***

Tools:

Set of sockets, (16mm), hydraulic jack, block of wood, wheel chocks, jack stands, floor jack, safety glasses, torque wrench

Applicable Models:

Mercedes-Benz W211 (2003-09)

Parts Required:

Motor mounts and fasteners

Hot Tip:

Replace in pairs

Performance Gain:

Reduce engine vibration

Complementary Modification:

Replace transmission mounts

The motor mounts on Mercedes-Benz W211 models secure the engine to the subframe while insulating the chassis from engine vibration. The mounts are rubber and filled with a hydraulic fluid to ensure the best vibration to stiffness ratio, resulting in a smooth ride and a solid feel. When an engine mount begins to fail, you will feel more vibrations from the engine. The engine may sag in the engine bay or the engine may have excessive movement under torque if a mount is broken. When working under your vehicle, you may notice fluid leaking out of your engine mount. This means the mount has failed and should be replaced. I suggest replacing one side at a time, while supporting the engine from below.

4MATIC W211 models do not have a lot of room for engine movement and access to the mounts. When replacing mounts on a 4MATIC, Mercedes-Benz suggests removing the front drive axles. What I like to do is: for the left side, remove the drive axle, then jack the engine and remove the mount. For the right side, I prefer to remove the alternator. It is faster and easier than getting the drive axle out. When replacing them, it's best to do so in pairs. However, this is no issue with RWD models. With 4MATIC models, pick your battle. If you have time and are up for a day's worth of work, replace both. If time and money are not on your side, replace only the fault side.

Remember that your car may have been serviced before and had parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve, as they grow older. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Jack up the front of your vehicle. See our tech article on jacking up your vehicle.

Remove the engine splash shields and reinforcement plates. Refer to those articles should you need assistance.

The following steps highlight removing the right side engine mount. Only remove the side you are currently replacing. Do one side at a time. The procedure is similar for the left side. I will describe how to replace the mounts for each side and RWD and 4MATIC models. If you are replacing mounts on RWD models, ignore the steps for alternator removing and front drive axle removing.

This photo shows a right side mount (red arrow) on a 4MATC model.
Figure 1

This photo shows a right side mount (red arrow) on a 4MATC model. With the alternator removed you have access to the mount, which can be easily replaced. To replace a right side mount, start by removing the alternator. See our tech article on alternator replacing.

Working on the right side subframe, remove the 13mm lower motor mount fastener (red arrow).
Figure 2

Working on the right side subframe, remove the 13mm lower motor mount fastener (red arrow).

Next, remove the upper motor mount fastener (red arrow).
Figure 3

Next, remove the upper motor mount fastener (red arrow). This bolt it notoriously hard to break free. This is due to its size and lack of access. I suggest using a 16mm wrench to break it free. Then remove it using a long extension.

When replacing the right side mount, you will want to jack as close to the engine mount bracket as possible.
Figure 4

When replacing the right side mount, you will want to jack as close to the engine mount bracket as possible. Next, support the engine from below using a jack. Place a block of wood between the corner of the engine oil pan and jack pad. Raise the jack until the engine mount bracket (red arrow) is about one-inch from the mount.

Remove the mount from the subframe through the front of the engine.
Figure 5

Remove the mount from the subframe through the front of the engine. If you have a RWD drive model, you will simply remove the mount from below, pulling it out from between the engine and the subframe.

Install the new engine mount.
Figure 6

Install the new engine mount. Be sure that the mount tab (red arrow) lines up with the slot (green arrow) on the engine mount bracket. Slowly lower the engine down on the mount. Install the new engine mount nuts and torque.

Working on the left side subframe, remove the 13mm lower motor mount fastener (red arrow).
Figure 7

Working on the left side subframe, remove the 13mm lower motor mount fastener (red arrow).

Next, remove the upper motor mount fastener (red arrow).
Figure 8

Next, remove the upper motor mount fastener (red arrow). This bolt it notoriously hard to break free. This is due to its size and lack of access. I suggest using a 16mm wrench to break it free, then removing it using a long extension. For the left side, it is a bit easier to break it free with a wrench from below. Remove the left front drive axle. See our tech article on front drive axle replacing. When replacing the left side mount, you will want to jack as close to the engine mount bracket as possible. Next, support the engine from below using jack. Place a block of wood between a corner of the engine oil pan and jack pad. Raise the jack until the engine mount bracket is about one-inch from the mount. Remove the mount from the subframe through the drive axle area. If you have a RWD drive model, you will simply remove the mount from below, pulling it out from between the engine and the subframe.

Install a new engine mount.
Figure 9

Install a new engine mount. Be sure that the mount tab (red arrow) lines up with the slot (green arrow) on the engine mount bracket. Slowly lower the engine down on the mount. Install new engine mount nuts and torque.

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Comments and Suggestions:
Jon Comments: I have a 2007 e280 that was fitted with the factory AMG sports pack for that model. Require gearbox and engine mounts.
Did not see that vehicle on your choice list and hope you may be able to assist.
February 9, 2016
  Followup from the Pelican Staff: I’m not the best with part numbers.

Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.

- Nick at Pelican Parts
 
Andie Comments: Does this engine mount replacement procedure & also the transmission mount procedure apply to an 05 C240 4MATIC W203?
I couldn't find any instructions in the W203 section, just wanted to double check before I start.

I appreciate all the information on the site, we'll done.

Thank you!
January 16, 2016
  Followup from the Pelican Staff: Applicable Models:

Mercedes-Benz W211 (2003-09) - Nick at Pelican Parts
 

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