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Pelican Technical Article:

Engine Mount Replacement

Tom Morr

Time:

1 hour1 hr

Tab:

$150

Talent:

***

Tools:

16mm, 13mm, 8mm wrench, 16mm, 13mm, 8mm socket with extension

Applicable Models:

Mercedes-Benz R170 (1998-04)

Parts Required:

New engine mounts

Hot Tip:

Make sure you support the engine correctly when replacing the mounts

Performance Gain:

Smoother shifts and driving

Complementary Modification:

Replace transmission mount

The engine mounts on a car are what hold the engine to the chassis. Almost all engine mounts have a rubber portion that allows a small amount of flex to reduce vibrations from the engine. These can wear out and cause all kinds of problems including difficult shifting and vibrations while the engine is running. The rubber portion of the engine mount is particularly susceptible to failure and if you have 75,000 miles or more on your car your mounts are probably in need of replacement. Heat and oil can take its toll on the mount, causing the rubber portion to crack and separate. When this happens, the mount collapses and no longer supports the engine correctly. Replacement is easy and should only take an hour.

Begin by jacking the car up and securing it on jackstands. Please see our article on safely jacking up and supporting your vehicle.

You will want to remove the under body engine tray. It is held in place by four 8mm screws. Remove these and lower the tray out of the way.

There are two engine mounts: one on the right and left side of the engine. The mounts are specific to each side as they both have locating points that only fit the proper side. We will begin by replacing the left side engine mount.

You will see the access hole for the lower mounting bolt on the cross member by the A-arm support. Place a 13mm socket and remove the bolt.

While you can use a 16mm wrench and loosen the top bolt from below I found it easier to use a couple of long extensions and remove the bolt from above.

With the two bolts removed place a 6 inch by 12 inch piece of flat wood under the oil pan and gently lift the engine to give you enough clearance to get the old mount out and the new one in. Do not place the jack directly on the pan as you can damage the pan unless you distribute the load. Take care when lifting the engine that you do not strain any electrical or vacuum lines and that you do not lift it enough for the bell housing to hit the chassis. Line up the new mount with the engine support, carefully lower the engine down, replace the bolts and tighten everything up.

Moving to the right side the access hole is on the opposite side of the cross member. Use your 13mm socket and remove the bolt.

There is a shield over the steering dampener that you will want to remove, I have heard of people successfully replacing the mounts without removing it but I have never tried. There are 8mm nuts that need to be removed. Remove the nuts and the shield.

You will now have access to the right side mount. It is a tight fit but you can get a 16mm socket and driver on the nut from below. It is hard to get leverage on this so if needed, you can use a bar to leverage between the engine and the wrench to help break the mounting bolt loose.

Follow the same procedures for lifting the engine and replacing the mount as described for the left hand side.

This photo illustrates how the mounts are specific to each side.
Figure 1

This photo illustrates how the mounts are specific to each side.

You will want to remove the under body engine tray.
Figure 2

You will want to remove the under body engine tray. It is held in place by four 8mm screws (red arrows). Remove these and lower the tray out of the way.

You will see the access hole for the lower mounting bolt on the cross member by the A-arm support (yellow arrow).
Figure 3

You will see the access hole for the lower mounting bolt on the cross member by the A-arm support (yellow arrow).

Place a 13mm socket and remove the bolt (red arrow).
Figure 4

Place a 13mm socket and remove the bolt (red arrow).

While you can use a 16mm wrench and loosen the top bolt from below (yellow arrow).
Figure 5

While you can use a 16mm wrench and loosen the top bolt from below (yellow arrow).

I found it easier to use a couple of long extensions and remove the bolt from above (yellow arrow).
Figure 6

I found it easier to use a couple of long extensions and remove the bolt from above (yellow arrow).

With the two bolts removed place a 6 inch by 12 inch piece of flat wood under the oil pan and gently lift the engine to give you enough clearance to get the old mount out and the new one in.
Figure 7

With the two bolts removed place a 6 inch by 12 inch piece of flat wood under the oil pan and gently lift the engine to give you enough clearance to get the old mount out and the new one in. Do not place the jack directly on the pan as you can damage the pan unless you distribute the load. Take care when lifting the engine that you do not strain any electrical or vacuum lines and that you do not lift it enough for the bell housing to hit the chassis. Line up the new mount with the engine support, carefully lower the engine down and tighten everything up

Moving to the right side the access hole is on the opposite side of the cross member (yellow arrow).
Figure 8

Moving to the right side the access hole is on the opposite side of the cross member (yellow arrow). Use your 13mm socket and remove the bolt.

There is a shield over the steering dampener that you will want to remove, I have heard of people successfully replacing the mounts without removing it but I have never tried.
Figure 9

There is a shield over the steering dampener that you will want to remove, I have heard of people successfully replacing the mounts without removing it but I have never tried. There are 8mm nuts (red arrow) that need to be removed. Remove the nuts and the shield.

You will now have access to the right side mount.
Figure 10

You will now have access to the right side mount. It is a tight fit but you can get a 16mm socket and driver (red arrow) on the nut from below. It is hard to get leverage on this so if you need to you can use a bar to leverage between the engine and the wrench to help break the mounting bolt loose.

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Comments and Suggestions:
Dave F. Comments: When working on the driver side mount you HAVE to turn the steering wheel to right to about 2 O'Clock in order to get it out.
October 23, 2016
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
erf Comments: Great article, thanks. Two comments:

1 I have to strongly agree with CK - you must remove the nearby bolt on the steering damper and temporarily relocate the damper in order to extract the mount. It's just a physical access thing - no way will the mount come out otherwise.

2 In my '98 230 I found old OEM P/N 2022401917 installed at the left mount. This P/N is contrary to both the Pelican and OEM/EPC catalogs which both recommend 2032400317. These recommended parts *did not* fit my car. The discrepancy was at the top mounting surface - where the mount joins the engine bracket. 2022401917 has a flat surface, while 2032400317 doesn't. 2032400317 simply doesn't work.

Some internet research leads me to believe there are factory variations in play here.
December 28, 2015
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
CK Comments: Great tutorial. I replaced both mounts today as well as the transmission moGreat tutorial. I replaced both mounts today as well as the transmission mount.

I would just like to add a couple things that might help someone else out.

On the left side mount if you remove a bolt on the steering damper and push it back to the rear of the car it gives enough room to remove the mount without having to lift the motor really high.

Also you may want to make sure to have something under the car to catch any oil from the old mount. Mine leaked a lot oil as I removed it.

It took 3 hours total to do both mounts and the transmission mount. I took my time and have never done it before. Easy DIY and saves a ton of $.
Cheryl

I would just like to add a couple things that might help someone else out.

On the left side mount if you remove a bolt on the steering damper and push it back to the rear of the car it gives enough room to remove the mount without having to lift the motor really high.

Also you may want to make sure to have something under the car to catch any oil from the old mount. Mine leaked a lot oil as I removed it.

It took 3 hours total to do both mounts and the transmission mount. I took my time and have never done it before. Easy DIY and saves a ton of $.
Cheryl
October 24, 2015
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
Robert Comments: How do you get the mount past the steering linkage with out removing it
September 26, 2015
  Followup from the Pelican Staff: Did you remove the heat shield? If that didn't give enough room ,t eh linkage may have to be detached. - Nick at Pelican Parts  
kolton Comments: Hey so i replaced the left engine mount using the instructions that the page had shown and it worked great. The downside is when i started the car and put it in gear it shook and rattled more than before i put the new engine mount in. Whats next? Im not sure where to go and what to check from this point?
September 14, 2015
  Followup from the Pelican Staff: Is the engine mount in correct? Check if it sitting flush at both mounting points.- Nick at Pelican Parts  

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