[zz4x4]

I had the very common "shaking at idle" issue so decided to replace the engine mounts. It totally solved the problem! The car is smooth once again. Anyway, it went pretty smoothly and took about 3 hours total time. Here is a write-up in case anyone finds it useful. Please let me know if I need to address any of the content!
Jeff
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• Open hood and remove the air intake ducts to allow room to work
• Disconnect the battery due to shock hazard working near the hot starter terminal.
• Jack up / lift vehicle to a moderate height that can allow access to the engine from the top as well as bottom. I set mine using a 2 post frame lift to about 30 inches from the ground.
• Remove the lower engine cover panel under the vehicle.
• Using a 13mm socket, remove both lower engine mount bolts and set aside
• Using a floor jack or suitable lifting device, raise the engine via a piece of wood under the oil pan. The engine can be lifted about 3 inches before the AC hoses begin to show signs of stress. I don’t recommend going much further than this!
• Lower the steering rack about 2 inches. Using a deep well 18mm socket , retain the nut inside the subframe channel on the two rear bolts. Using another 18mm impact socket or wrench loosen the two rear bolts. Do not fully remove the rear two bolts but make them as loose as possible while still keeping the nut on the bolt. Completely remove the two front steering rack bolts using an 18mm open end wrench and impact socket. This will allow the rack to hang down but still allow easy reinstallation.
• At this point it is necessary to remove the upper engine mount bolts. On the V8, there is little room for a socket due to the exhaust manifold. With the engine raised it’s much easier to do this step though. From the top use a 16mm ( or 5/8”) ratcheting box end wrench and loosen the bolts. They will not come out due to their length, but the engine mounts will drop off the bolts when they are loosened enough.
• From the bottom of the car, fish the right side engine mount rearward and pull out between the cat , bellhousing, and subframe. You may need to raise the engine a tad if it won’t come out. It may take a little finessing and tugging to remove. The left side mount will come out towards the front between the steering rack and subframe.
• Press the new mounts into the same areas the old ones came from. Get into a position under the car where you are supported and can hold the engine mount against the upper bracket with one hand and still reach the upper bolt with a couple fingers of the other hand. As you press the mount against the upper bracket, screw the bolt into the mount. Just a couple threads is all you need. Now spin the mount clockwise to tighten while keeping a finger on the bolt. After several spins, you will feel there is a place where the mount locating pin will pop into the recess on the upper mount bracket. At this point the mount will no longer spin. You can now go to the top of the engine and fully tighten the bolt to ~55NM. Tightening the upper bolt is much easier while the engine is lifted so I recommend doing now.
• Reinstall the two front steering rack bolts / nuts and tighen all four bolts to spec.
• Lower the engine slowly watching for the engine mount threaded holes to stay in alignment with the subframe holes. Mine required no side to side adjustment but could be necessary with a crow bar.
• Reinstall lower mount bolts using Locktite and torque to ~35NM.
• Reinstall air ducts, lower engine cover, connect battery and your done!

 

[Ramunsa]

nice write up Thanks

 

[roadster49]

Did you have any problem inserting new mounts into position? Do you think this could be done if using jack stands? great write up. I am trying to find some pictures to help me visualize this. Thanks

 

[zz4x4]

I definitely think it can be done using jackstands for the chassis and a hydraulic floor jack to lift the engine. Lifting the engine to the right height is key to being able to remove / install the mounts since the subframe and other parts get in the way. Just take it slow and keep an eye on the engine connections (like the AC hoses).

 

[W220HI]

Nice write up! I have done this on my W210 and was wondering if it would be a real pain on this platform. Thanks for the info!
Jason

 

[Kilek]

• Lower the steering rack about 2 inches. Using a deep well 18mm socket , retain the nut inside the subframe channel on the two rear bolts. Using another 18mm impact socket or wrench loosen the two rear bolts. Do not fully remove the rear two bolts but make them as loose as possible while still keeping the nut on the bolt. Completely remove the two front steering rack bolts using an 18mm open end wrench and impact socket. This will allow the rack to hang down but still allow easy reinstallation.

Hello, I have come to this valuable guide and find myself confused at the point of lowering steering rack. I can not see the space to lower the rack more than just 0,6 inch. I have marked it to the picture. Could you please kindly advice where would it go?

 

[Kilek]

...unless steering rack will move forward :dunno:

 

[crunk04gtp]

Couple pics and comments after doing 1/2 this job.

Kilek, that steering rack comes pretty far forward, but my experience was the tolerances are still pretty tight. That hole is where it attaches to the vehicle

I suggest definitely having two 18mm sockets for the steering rack frame.

The bolt on top of the mounts is a bear. I ended up making a double angled breaker bar to be able to crack it. What I could not figure out though is now to properly torque it?

For those who have not but might attempt the job, notice the recess. I feel like if you got lucky on a ratcheting wrench that was just so it might be doable, but I definitely have no idea how y'all got a torque wrench on that thing given the exhaust manifold and proximity to firewall. My only thought was that you maybe had the engine up higher which made the side of the engine bay issue less of a problem? I feel like I went a bit higher than the recommended three inches though (didn't measure). Didn't see stress on a/c lines but didn't want to push my luck in case there was something I was missing.

Only did the passenger and tranny mounts. Hopefully doing the driver side over the break. I'll include some more pictures as that one looks to be considerably more tricky.

 

[muqaddar]

This write up was very helpful. I just did both engine mounts on my 2002 cl500. The passenger side was very easy. I did not have to drop the steering rack for the passenger side. Just used a short 16mm wrench to access the top bolts of the motor mounts. It's available on ebay specific to mercedes. Just do a search for mercedes engine mount wrench. Mine was $16. Without this wrench I would not have been able to get the top bolt torqued correctly on both sides. I also bought a 5/8" wrench socket to be used with this wrench on the driver side. Without it I was unable to get enough leverage and clearance to loosen the driver side top mount bolt head.

The driver side did give me a little trouble. Dropping the steering rack as suggested did not give me enough clearance. Since I did one side at a time I was unable to get the engine lifted to a proper height to allow enough clearance to slip old mount out and new one in. I did not want to remove both lower mount bolts at the same time in order to keep engine somewhat aligned. I went to Home Depot and bought a long 40mm height M8-1.25 bolt and threaded that into the bottom passenger side mount hole 2-3 turns. This allowed the passenger side to stay aligned. I was then able to lift the engine to allow enough clearance to allow removal and installation of the driver side mount. You'll need someone to put their finger on the driver side top bolt head to keep it from spinning while you install the driver side mount from underneath.

All in all a ver simple diy.

The dealer quoted me $1000 to replace both front mounts (parts and labor). What a joke! I got my mounts from autohausaz for $160. Follow this guide and save youself a bundle.

-Chet

 

[KevCarver]

I get a lot of movement in my shifter when I step on the gas hard from a standstill. So much so that it won't move side to side if I'm using manual shifting. Can I get away with just the trans mount, or do I need to do the engine mounts too?
'01 S430
I've been kicking around the idea of replacing them since I got the car in Feb, but was doing other stuff first. Also, my first attempt at putting the car on stands almost ended badly. Went a bit pear-shaped as I was lowering it back to the floor.

 

[muqaddar]

I see no problem in just doing the transmission mount. It's really easy. If it doesn't fix your problem then you can do the engine mounts later. I've also heard stuff about a bushing on the shifter going bad and requiring replacement. That could also be your problem.

I made my own car ramps using wood 2x10's, stacked 4 deep. When I need to lift the car on all sides I drive up on the ramps and then I use wooden blocks cut to about 30 inch lengths stacked 4 deep on both rear wheels. Makes it nice and level and also easy to work on.

 

[fasz]

Muqaddar, the car ramps are very interesting, please can you post a photo.

 

[KevCarver]

Indeed. Pics required!
Thanks for the reply. I'll have to look into that shifter bushing.

 

[muqaddar]

Here you go. It was very simple. I used the following length pieces, 24",
42", 60" and 72". Screwed each of the pieces together using 2.5" wood screws. I used 5 screws on each piece. Did this about 6 years ago and they are still going strong. They are heavy to move around but well worth it in my opinion.

 

[Fried Chicken]

Can this be done on an S500 with ABC?
I've already managed to do the passenger side, however the driver side seems exponentially more tricky.

I see the space at the bottom for the mount to be removed (after lowering steering rack), however I'm unable to reach the top bolt for the mount using a wrench (I'm so close though). The problem is the ABC lines that are in the way.

It's possible that I haven't raised the engine high enough

The WIS suggests removing the ABC tandem pump and loosening the A/C lines in order to remove the whole engine mount assembly (including mounting bracket).
I'd rather not do this to put it lightly. I'm considering loosening the tandem pump to reach top engine mount bolt, but my tensioner requires a torx that I do not have and that is where I'm stuck currently.

 

[LWB250]

Not sure if it would help, but there is an offset wrench that's used on the top bolt of the W140 chassis mounts as they are tough to get at:

Amazon.com : Mercedes Benz Offset 17mm Engine Mount Wrench : Other Products : Everything [email protected]@[email protected]@http://ecx.images-amazon.com/images/I/41iVCchp%[email protected]@[email protected]@41iVCchp%2B2L

This is the 17mm version, but there is a 16mm version as well.

As for changing the transmission mount only, do consider it. My motor mounts are fine at 98,000 miles, but I found the rubber in my transmission mount starting to shear off the metal portion, so I replaced it.

Dan

 

[KevCarver]

I found the wrench handy, as well as a second set of hands. I can't comment on ABC as my S430 isn't equipped with it.

 

[Fried Chicken]

The ABC pipes are in the way, I'm not even convinced loosening the ABC pump will allow the proper clearance. I think the Mercedes Offset Wrench might be what I need, but I really don't want to take everything apart simply because I can't reach a bolt that I can literally see. The frustration is immense! I'm absolutely flustered!

 

[Fried Chicken]

It's impossible.

I managed to get a stubby wrench on the bolt, but the bolt is being held on with enough force to stop an aircraft carrier.

I tried some convoluted method of putting a 1/2" breaker bar into the other end of the wrench and bashing it with a hammer. Getting one good hit in takes 10 minutes and 50% of the time you have to reset everything after that one good hit. It didn't budge shit.

Marinating the bolt in penetrating juice for 3 hours hasn't helped shit.

The engine mount itself is completely destroyed, I can literally turn it from the bottom, but it seems to turn infinitely. I have no idea what whichcraft is holding it together.

Yet here I am, a bolt I can see with my naked eye, but cannot for the life of me get off. I bought a set of crows hooks, but the set I bought comes in an array of metric sizes ranging from 10-17mm. It didn't include 16mm, because... life.

The water level from the N64 Zelda game has nothing on trying to get the driver's side motor mount off.
I think the ABC pump has to come off, but by its design, the removal requires disconnecting the lines, which is something I want to avoid about as much as the arab countries want to avoid a jewish neighbor.

If someone has some suggestion, I'm all ears. This has already turned into a two-day job, now it looks like the car is going to be sitting overnight again.

FUCK.

 

[KevCarver]

Where do you live anyway? Maybe someone that's done it and/or has the offset wrench is close enough to lend a hand?
The wrench with a long socket extension to bring it up above the engine is the way to go I think. Can't get full rotations, on it, but you can turn it by repositioning the wrench. A lot. But again, without having had to deal with ABC I can't say for sure. Even without ABC the driver side was significantly more difficult.
The top of the mount is keyed to fit without rotating, if I recall. It's my understanding that they are hydraulic, and similarly if you unbolt the bottom of a shock (or motorcycle fork) you can spin it without affecting the top. That's why the bottom will turn.