Mark out West

The only clue I had mine were overdue for replacement was oil leaks under the protective covers.

Checking the date codes, all three mounts were installed way back in 2008 at the factory. Not looking too good after 103K miles. About 1" shorter than the replacements.



The transmission mount looked even worse:



All three were totally collapsed but were not exhibiting any telltale signs of failure. It's a DIY job, even with floor stands and a jack, but expect 4 to 6 hours. And get a supply of Band-Aids, you'll need them.

JohnLane

OP they were only about ten years and 60,000 miles overdue!

Done on a hoist this is a two hour job the first time doing it.

An hour with some practice.

I’m sure it is much smoother at idle with fresh mounts.

Mark out West

Maybe some other cars, but did you do a C216 with the M156? Even without all the dead ends and trial-and-error, I still couldn't manage it in less than 2 hours. The WIS manual was very little help as well.

I'm a better than average DIY, and it took an hour alone just to remove the top bolts from the engine mounts. Some folks have posted YT videos and forum threads on how to remove mounts in various other Benzes, and it looks pretty straightforward. The C216 with the M156 is a different beast altogether, as i found out. Just a tiny gap between the wheel well and the valve covers, and partially blocked by the exhaust manifolds. Even with the special tool and a 20" 3/8 extension, I could only get one click at a twist on my ratchet before hitting the wheel tower.



Also, a lot of videos and postings tell you to remove the mounts out the back of the engine. That works for the passenger side mount, but there's no way to wiggle the new mount into place on the driver's side from the rear. Without having to drop the exhaust and remove the steering shaft I eventually loosened and dropped the steering rack slightly to gain the additional 1/2 inch needed to squeeze the new mount into place from the front, and even then it was a 10 minute struggle. Putting the top bolts back into the new mounts was just as time consuming as taking them out - limited space and bad angles.

Replacing the rear mount required removing the cross-brace.

One word of advice specific to the C216 (and maybe the W221). Loosen the A/C pipe vibration mount on the wheel tower before jacking the engine. It's a tight connection and the hose is very inflexible. You'll manage to damage the bracket if you don't.



Anybody else out there that did all three mounts in a hour? Sound off on the tricks.