I Just did front engine mounts on my 1999 clk320 (45,000 miles) yesterday. Symptom: vibration only when cold and in drive at a stop. No vibration in reverse at a stop. Once car warmed up, vibration went away. Reasoned that one mount must be bad since the engine torque places pressure on one mount when in drive and the other mount when in reverse. After reading this and other threads (Thanks Pancho, et.al.), my process was to unclip the air filter housing (so as to not stress the intake hose when lifting the engine) place car on 4 jack stands. I did all the following work from under the car: removed the plastic center pan under the engine (4 bolts - easy), removed the steering damper (2 bolts - easy), tried to remove the center link at pitman arm but couldn't get it separated - so left it in place, removed the bottom bolts of the left (driver's side) and right mounts. Removed the top mount with a 5/8 inch box end wrench and pry bar (holding the wrench on top of the nut with my left hand, I was able to wedge the pry bar against the wrench and engine to work the nuts loose (mine were on tight). The right side had a shield over the idler arm that I had to remove and shove out of the way (2 small screws - easy). Using a floor jack and a 2 by 6 piece of wood, jacked up the engine and pulled the mounts out (it was tight with the center link in place but I was able to work the mounts out and get new mounts in by moving the pitman arm and steering link (put key in ignition to unlock steering wheel)- removing 2 single-screw mounts that hold the transmission oil cooler lines and pushing those out of the way helped a little for the left mount). Put new (Corteco 2032411113 - apparently, for a 99 CLK320, there are two different mounts pending the VIN number) - $45 each - rmeuropean) mounts in place being careful notch on top of mount went into slit on engine. Hand tightened top nuts. Lowered engine and put lower nuts in. Tightened using 5/8 box end wrench and pry bar for top nuts. Put shield, trans cooler lines, steering damper, bottom engine shield and air filter cover back in place. Checked rear transmission mount with pry bar - good movement with no clunking - so ok. Lowered car. No more vibration! My cost: $90. I found a shop that would do it for $500.

 

Pancho thank you for the information! I did this job this weekend along with the trans mount and your pictures really helped. My car idles smoothly again!

I was VERY glad that I purchased some ratcheting open-end wrenches for the top bolts. It would have taken a lot longer without them.

Mike
2002 CLK430 Cabriolet

 

Hi,

Great write-up from what I can tell. But when I click on the pictures that Pancho posted, nothing happens. I can only see the thumbnails.

Does anyone know how I could see the pictures (with the write-up)?

Thank you!
Hans

 

I don't recall seeing this in any of the motor mount threads but from my experience its a complete waste of time trying to break the top bolts loose with a ratchet/extension on the 16mm "dog bone" tool made for this job. I couldn't get enough leverage and it was a pain to keep the 16mm tool square on the bolt head. What I did was place the dog bone on the top bolt and use a medium sized pry bar (wedged against the exhaust manifold for leverage) to break them loose (from underneath the car of course). After doing this about 3 times they came out by hand. I fought with the drivers side mount for at least an hour until I tried this. I had the passenger side done in about 15 minutes while stopping to open a beer. I'm pretty confident I could do this job in under 2 hours start to finish if I had to do it again.

Up until this point I followed the write up, had the car in the air on jack stands, etc. I had plenty of room for the mounts to come out underneath without doing anything extra.

 

I see a few people have asked about where to jack up the car. I used a piece of 2x4 between the engine/trans and a piece of 4x4 under the diff and raised it with a floor jack.

Here’s an alternative to using the factory MB jack if you prefer. A 5/8” x 8” stud fits inside the factory jacking point. I assume you could also use a grade 8 bolt. Just be aware of the jack placement if you’re going to put the car on jack stands. And no....my car is normally not this dirty but it's winter here.

 

Just tackled the today, mostly painless. I went with a different route, I couldn't generate enough torque from the bottom for the driver side. Even wedging a bar like some mentioned, that didn't work. I have skinny flexible hands so i was able to squeeze it through from the top. Getting my finger tips on the ratchet was enough to break the bolt loose.

Squeeze hands between those two hoses

 

If you loo at the circled area, you'll see my ratchet

 

I just finished doing this job plus the trans mount yesterday on my 03 CLK 430. A big 'Thank You' to Pancho and others contributing to this thread.
Once I got the car jacked up, I was able to do everything else from underneath without having to disconnect or move anything (lucky me)! Found the driver's side to be less difficult, as the mount had enough room to come out. Passenger side was a little more difficult with the exhaust manifold in the way- just had to jack the engine up a little higher for more wiggle room.
I'm very happy with the ride quality and can't wait to drive again.


Out with the old! I used W209 motor mounts.

Tools of the trade: The tiny 16mm and ratcheting 5/8 were life savers with the upper mounts- with a little leverage from a ratchet.