Mercedes-Benz Forum banner
1 - 20 of 25 Posts

· Registered
2007 S550
Joined
·
64 Posts
Discussion Starter · #1 ·
While sitting at idle this morning, my attention was drawn to a vibration coming through my driver seat. I checked my engine/motor mounts and, sure enough, my driver's side motor mount is shot. I mean, the motor looks like it's going to jump out of the car when I put my foot on the brake and give it a little gas. So, I have a new project on the list.

After doing a little research, it appears that there are 3 mounts that I should replace: 2 front and 1 rear (transmission) mount. Google searches turn up videos and info on w220 mount replacements, but I haven't found anything on the w221. Has anyone taken on this task? I could really use some pointers from someone who has changed theirs out, please.
 

· Registered
2007 S550
Joined
·
64 Posts
Discussion Starter · #3 ·
Thank you, Konigstiger! This is very helpful.

I am wondering if I really need to detach the steering coupling to do this job like it states in the instructions. In all of the research I've done (mostly W220 info), nobody messes with the steering coupling. Although, different car so it may very well be necessary here. I guess I'll find out soon enough.

My "lift" is going to be a hydraulic jack and some wood pieces underneath the engine. I priced out the Mercedes lift/hoist about a month ago. It was around $3K-$4K. I can't justify that at this point.

Given the difficulty in finding DIY information on this, I'll document this as best I can for the forum.
 

· Outstanding Contributor W221 Moderator
2015 S550, 2010 E350 P1/P2, 2002 ML320
Joined
·
2,670 Posts
Given the difficulty in finding DIY information on this, I'll document this as best I can for the forum.
Thank you Jack! I replaced mine a few months back, just cannot seem to find enough time for the documentation part (pics, details, etc.)

My lessons learned (2008 S550 2WD);

*** These mounts are full of liquid, when removing them keep your face out from under them or you will get 'moisturized'!
- I used the Harbor Freight engine support bar, not a professional quality tool but it works, just take care where you set the feet. (https://www.harborfreight.com/1000-lb-capacity-engine-support-bar-96524.html)
- The drivers' (Left in the US) side mount can be removed from the front, just need to use a pry bar to wedge the engine over toward the passenger's side.
- The passenger's side mount is much more easily removed toward the rear if you detach the sway bar mount at the body frame and swivel the sway bar down
- This is the first Mercedes I've owned where the mount tool seems to actually make a difference. (Example of the tool here -- not my listing, just an example. https://www.amazon.com/Mercedes-Offset-Engine-Mount-Wrench/dp/B019L7IDU6)
- Tap out the holes in the new mounts with the correct thread prior to installing them. I had one that was burred a bit and it took me an hour of fiddling with trying to get the top bolt in before I figured it out. I removed it, tapped it and had it back in the car and bolted in place within 10min.
 

· Registered
2007 S550
Joined
·
64 Posts
Discussion Starter · #5 ·
Very helpful info, dlafever! Thank you!

I just purchased the engine support bar from Harbor Freight as you suggested. I like that solution much better than jacking it up from underneath.

I will also purchase the mount tool when I purchase the engine mounts. I'm just waiting for the supplier to verify that I chose the right mounts for my car (they require verification before they ship). I hope to get it done this weekend.

Did you disconnect the steering coupling when you replaced yours?
 

· Outstanding Contributor W221 Moderator
2015 S550, 2010 E350 P1/P2, 2002 ML320
Joined
·
2,670 Posts
No I did not. That is only required if you remove the drivers' side mount rearward. It just seemed like I would not be able to get my hands/tools up in there to do it correctly, so I opted for the forward exit method.
 

· Registered
2007 S550
Joined
·
64 Posts
Discussion Starter · #7 ·
Mission accomplished

I'm happy to report that I replaced both motor mounts and my transmission mount today. :beerchugr:

It was a tedious project, but well worth the effort. It took me about 8 hours. Yes, I'm slow.

What a difference in how quiet my car is! I can't get over it. I can hardly even hear the engine now. I guess that's what it was like when I got the car back in 2008, but I had forgotten how quiet it was.

Thank you guys for the guidance! The Harbor Freight engine hoist worked like a charm and I pulled the passenger side mount through the back by dropping the sway bar. The driver's side mount just dropped straight down past the oil pan.

I will post my DIY experience in the next day or two. Glad to have that project in the rear view!
 

· Registered
2007 S550
Joined
·
64 Posts
Discussion Starter · #9 ·
This job was not super difficult, but it was very tedious. One post that I read said that it is a “fiddle” job because there is a lot of fiddling with the mount bolts, heat shields, and mounts to get them out and into position. I concur with that assessment. The job would have been a little easier if my hands and arms were just a little bit smaller. I made some mistakes along the way and I’ll share them here so that, hopefully, it will prevent others from wasting their time on the same mistakes that I made.

1. I made sure the steering wheel was straight, then secured it with 2 bungee cords to the brake pedal. My hope was that I wouldn’t need to detach the steering coupling as dlafever mentioned he didn’t need to detach his. I wasn’t sure if I would get away with it, so I secured the steering wheel just in case (see Fig. 1).


2. I released the hood latch, then lifted the car and set it on top of my 10” cradles. Since I was going to be working from the top and underneath the car, I didn’t want to lift it very high. The 10” cradles were perfect. I also left the lift arms under the car for added safety since I knew I was going to be crawling under the car (see Fig 2).


3. I opened the hood and removed the engine cover (see Fig 3). 


4. I needed a place to put the feet of the engine hoist that I purchased from Harbor Freight (see dlafever’s link in this thread). When the hood is open, on the far right and left sides of the engine bay, there are plastic pieces that cover metal brackets (See Fig 4). I removed the plastic, exposing the brackets by gently lifting up the pieces. They come right up without any problem. If I hadn’t removed the plastic, it would have fractured under the weight of the engine. This was the only place I could find that looked like it could support the weight of the engine and still fit w/ the Harbor Freight engine mount.

5. I put the engine hoist on the car with the hoist feet over the brackets (see Fig 5). The engine hoist bracket on the car is a loop that is front and center of the engine. You can’t miss it. The chain that came with the engine hoist would not fit through the loop, so I just put the t-end of the bolt through the loop. This worked out fine, although it minimizes your ability to maneuver the engine much when working on the car. I obsessed about how much weight was being transferred to the feet of the hoist and worried that those metal brackets they were resting on would bend. I didn’t need to worry, they were very strong.


6. The next thing I did was tape the special 16mm tool (see dlafever’s link below) that I got on Amazon to the end of a ratchet extension (See Fig 6). I put the tool on the extension such that if I held the extension vertically, the tool made an “L” shape that angles down towards the floor. This is important. If you put the tool on the extension such that it angles up, it will not catch on the bolt nearly as well. The special tool accepts a 3/8” ratchet. All my extensions are 1/2” and short, so I needed to use an adapter and a couple of extensions. While this worked, it would have been better to just have one long 3/8” extension because the added width of the adapter inhibits the turning radius in an area that is already very tight. I would not recommend doing this job without the special tool. Taping the extension(s) to the tool proved to be a good idea - it prevented the assembly from coming apart.


7. After setting up the tool assembly, I made my first mistake by attempting to take off the top bolt of the driver’s side engine mount first. It’s really tight, hard to get the wrench on, and very little room to turn the bolt once the wrench is on the bolt. What I should have done is removed the BOTTOM bolts of both mounts first, then lifted the engine, then taken off the top ones. After about an hour of fiddling with one bolt turning about 1/8 of a turn before having to move the wrench to a different position, I figured this out. So, remember this: remove the bottom bolts on the mounts first, then hoist the engine, then remove the top bolts.


8. Hoisting the engine: One of the reasons this project took me so long is that I was very nervous that I was going to break something while hoisting the engine. Specifically, I was worried about putting too much stress where the engine bolts to the bell housing of the transmission and I was worried about damaging the steering because I didn’t disconnect the coupler. I’m not sure if I should even worry about those things, but I’ve never hoisted an engine, nor have I dropped a transmission, so I don’t know what I should worry about. So, I raised the engine very slowly and stopped frequently to inspect and make sure nothing was binding. I tried to lift as little as possible to get the job done. In retrospect, I probably should have lifted higher sooner because I found myself unable to move the mounts enough to get them in or out, then I’d lift a little, try again, lift a little, try again, lift a little, try again…..


9. Driver’s side engine mount: This one was the most difficult for me. Access is very tight (See Fig 7). As mentioned before, getting the top bolt off the mount is very tedious, but goes a lot faster when the engine is hoisted a little. For one thing, there’s just a little better angle. And another benefit is that you can push on the engine and it will move a little, giving you even more room. I was able to drop the mount straight down between the chassis and the oil pan. When putting the new mount in, I brought it up through the same passage. However, I had to hoist the engine a bit more because the new mounts are taller than the old mounts. Now, here’s a little pointer. The mounts have a rubber cover that goes over the top of them. This cover moves all over the place when you are trying to get the mount positioned. Next time, I will tape the rubber cover to the mount to prevent it from sliding around. Also, I would draw a vertical line at the metal tab all the way down the side of the rubber cover so that it’s easy to see where the tab is located. The metal tab faces outwards and slides into the notch on the engine mount. I spent a lot of time lining this thing up and getting that cover just right. Also, when you are installing the new mount, tighten the top bolt down first and to the proper torque spec. Well…yes, I used a torque wrench and I tightened it to spec, but since the special tool moves the leverage point, I’m not sure how accurate the torque is. The mount will be hoisted with the engine so the bottom bolt hole may be too high to start. If it is too high, wait until you install the other mount before lowering the engine to get the bottom bolt in.


10. Passenger side engine mount: This one was easier for me. I figured there were 3 options to get the old mount out and the new mount in: i) remove the alternator and take it out/in the front of the engine; ii) remove the exhaust and take it out/in the back; iii) remove the bottom bolt on the sway bar link and 2 bolts on the sway bar bracket and pull it out the back (just as dlafever did). I pondered all 3 options and came to the same conclusion as dlafever. The easiest alternative is option #3. The only drawback is that the sway bar link attaches to the top of the steering knuckle (although there is no need to detach the upper end), which means an alignment might be necessary if you go this route. Fortunately, an alignment doesn’t appear to have been necessary for me. I forgot to take pictures of the sway bar link, but you will see it and the bracket clear as day when you are contemplating how you are going to get the mount out and in. Once you have the old mount out and the new mount in place, then bolt the top first. Then, when the top one is done, lower the engine in small increments until the bottom mount bolt is long enough to reach the bolt hole and get that bolt started. Then, go over to the driver’s side mount and get that bottom bolt started if it isn’t already started. Once both bottom bolts are started, then lower the engine completely and tighten the bottom bolts to the proper torque specs.


11. To finish up, I reinstalled the sway bar link bolt, took off the engine hoist, put the engine cover back on, put the plastic covers in the engine bay back on, put the splash guards back on, removed the bungee cords from the steering wheel, and took the car off the cradles.


12. The next day (actually, later the same day since I did the motor mounts until about 1:30am), I did the transmission mount. It is really easy and there are several videos on how to replace a transmission mount on youtube, so I won’t go into detail on that here.

All-in-all, this was a long and tedious project. I spent about 8 hours on this, primarily because I was so cautious and because I tried removing the top bolts before hoisting the engine. If I had to do it again in the near future, it would probably take me about 3 hours as long as I didn’t run into any seized bolts or anything unexpected. Special thanks to Konigstiger for the WIS instructions (which include the torque specs) and dlafever for the guidance on the engine hoist, steering coupler not needing to be removed, and the hydraulic fluid in the face (which, yes, it did happen to me too, even though you warned me)!
 

Attachments

· Registered
2008 S550 4Matic
Joined
·
2 Posts
I know this thread is a little old but I was wondering where exactly you jacked up the transmission from when replacing the mount. It's my first time doing any sort of repairs short of oil/fluid changes and I just wanted to be extra sure so I don't damage anything.

Also, would you happen to have any extra info/pictures/instructions on tinkering with the sway bar stuff when replacing the motor mounts? I was hoping I might be able to do the motor mounts without having to remove anything, like some youtube videos of other mercedes vehicles depict. I also, only have a jack and was planning to go the jack+blocks of wood route.

Thanks! There's some really great info here!
 

· Outstanding Contributor W221 Moderator
2015 S550, 2010 E350 P1/P2, 2002 ML320
Joined
·
2,670 Posts
When I replaced mine, now and in the past, I've just used a piece of 3/4" plywood roughly the same size as the transmission pan to distribute the weight. You only need to raise the transmission 10mm, just enough to get the old mount out and new mount in. Now, this is from my non-4MATIC experience, not sure how that might change things.
 

· Registered
Joined
·
1,563 Posts
I don't know why people are saying on here it's taken 8 hours. I brought my indy and new motor mounts and tranny mount to a "self serve garage" where you get a bay with a lift for $20 an hour. I basically watched as he swapped out both engine mounts and the trans mount, and was done in exactly two hours. Unbolted the bracket that holds the steering rack, the 2 brackets that hold the sway bar, uncoupled the steering, lift the engine a few inches, out the motor mounts come, in go the new, put back together, Done. The trans mount, took all of four minutes. Maybe having the lift helped a lot. This lift lifts the whole car as high as you want it to be. Mounts were about $80 each for genuine MBZ parts, lift rental $50 and indy labor $300. NOW when sitting at a red light, No vibration, smooth as silk and quiet too. Like a Benz is supposed to be! My indy wasn't aware this shop existed where you can rent a bay with a lift, so he'll be using that service in the future on some jobs, and the shop people are happy to have a contact with a super capable indy who can come to help their customers sometimes. They sometimes get customers who think they can do a job, and learn that they can't. So it was a Win-Win for us all. OH... and the dealer I bought the car from barely two months ago, lied when he said he had "replaced one motor mount". The parts that came off the car were original and not one was any close to new.
 

· Outstanding Contributor W221 Moderator
2015 S550, 2010 E350 P1/P2, 2002 ML320
Joined
·
2,670 Posts
It's about 2h for me at home with the lift. 8hrs ... something went wrong. Wrong tools, wrong approach, wrong something. NOW, 4MATIC I understand is much more involved.
 

· Registered
Joined
·
1,563 Posts
It's always easy for something to go wrong. And 4Matic definitely changes the equation, I'm not sure just how much, Probably in this instance lucky to not have 4Matic, although I wouldn't mind.
 

· Registered
Joined
·
2 Posts
07 s550 4matic
I found it easiest to remove the engine mounts by dropping the steering rack.
Once you have the engine mounts loose, disconnect and lower the steering rack a few inches, then lift the engine as far as it will go.
You should have enough space to remove and insert the engine mounts from the bottom of the car. (some persuasion required)
 

· Registered
2007 S550
Joined
·
203 Posts
07 s550 4matic
I found it easiest to remove the engine mounts by dropping the steering rack.
Once you have the engine mounts loose, disconnect and lower the steering rack a few inches, then lift the engine as far as it will go.
You should have enough space to remove and insert the engine mounts from the bottom of the car. (some persuasion required)
I just did this job a few months ago, no need to drop the steering rack. Following the instructions in WIS, they're good and efficient.
 

· Registered
2005 S430 Tan/Black, 2010 S550 Black/Black
Joined
·
15 Posts
Hello, having trouble with replacing the motor mounts on 2010 S550 4matic. The video below insists that you must remove the cv axles to get enough clearance for raising the engine to put the new mounts in. However, not seeing anyone mention that anywhere else. I’m having issues removing said axles and wanted to confirm if removing the cv axles is necessary for replacing engine mounts on 4matic s550. Link below if interested.

 

· Registered
S500 4Matic 2005, S550 4Matic 2013
Joined
·
1,552 Posts
Yes I had to remove the passenger side cv axle on my 2013 S550 4Matic. I replaced the bushing on the axle while I was in there since it had started to sweep a little. Not a job I would like to do again.
 
1 - 20 of 25 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top