Engine Mounts: Function of Age?
 

From the degree to which the engine shakes at shutoff, I suspect I need new engine mounts on my 98 E300D. At only 73k miles this surprises me. But perhaps mounts could need replaced just by virtue of being 15 years old. What do you think?

Rubber dry rots over time. Plus, if anything has leaked oil or fuel onto them they'll degrade even faster.

-J

Yes, time takes its toll on rubber products; don't forget that trans mount as well, it is a fairly low cost item.

BOTH - I've changed 'em out in 10 years, and 4 years. 90K to 150K........ You have to be aware of the symptom(s) of each MB diesel needing them, beyond the shakes. Pricey little suckers on the '99 E300TD.

I'm going to email you a short video of the 98 shutting down....see what you think.

I wouldn't worry too much about the engine wiggling around. The thing that really tells you if the mounts are shot is to put it in drive, neutral and reverse. If there's a big difference in the vibration between the three, you probably need new mounts.

By "big" vibration, I mean one position will feel pretty good but another will have a deep, resonant vibration. Most often, reverse is the smoothest because the engine is rarely torqued in that direction.

On my car, I replaced both mounts and then, about 2 years later, the right mount again needed replacing. I left the other one alone at that point.

By that test my mounts appear to be in good shape.

OK.

Get an eyeball on the mounts. You may see more compression of the left/portside mount, than the right/starboard one.

Although difficult to describe, the car (99 E300) evidenced a 'moaning or groaning' sound when starting out in a low-speed hard right turn out of my driveway. That was the evidence that the left/portside was particularly compressed.

Here too, I would not try to save a buck by buying a cheaper, aftermarket branding set of mounts, other than prescribed by MB.

Here's a shot of my mount after I replaced it. Curiosity got the best of me and I cut it in half using my band saw.

http://i3.photobucket.com/albums/y71...s/423502e0.jpg

The concentric rings of rubber at the top are what actually holds the engine up. That rubber pad in the center will sink and come in contact with the center part when the mount gets weak. This contact is what causes the vibration. Normally, there is damping fluid in the mount and it acts like a shock absorber.

New, the top two alum flanges are 17mm apart. They are considered collapsed at 13mm.

Your 10mm x 3/8 drive socket is probably 13mm OD. Measure it and use it as a feeler gauge.