Confirmation on Motor Mount - PeachParts Mercedes-Benz Forum

dproudfo · #1 07-08-2008, 11:42 PM

Hey everyone,

I'm planning on ordering a replacement motor mount tomorrow for my '95 E420 (86K on the clock) and have done the following diagnostics:

The car has a low rumble at a stop with the transmission in Drive. Rumble increases (is more constant) with the AC compressor running. When transmission is shifted to Neutral the rumble goes away completely. When shifted to Reverse I'm unable to notice any rumble.

This leads me to think that it's just the passenger motor mount (visibly is collapsed) and not necessarily both mounts. At $110 a pop it would be nice to resolve the issue with a single replacement. (not to mention the fact that it would be a little bit easier to replace than the driver's side mount)

Just wanted to get a little feedback prior to ordering the part.

Thanks in advance!!

duxthe1 · #2 07-09-2008, 12:17 AM

In the shop we would replace both. As a DIYer I think your best bet is to just do the passenger side mount. It is under more stress than the drivers side mount and fails sooner. It is also the easier of the two to replace and is certain to resolve your problem. It would be a good idea to check your trans mount while you are under the car. If it's bottomed out I'd do it at the same time. To check just pull down on the driveshaft behind the front flex disc. If it's got some spring to it, its still good. If it has no give or you can bottom it out then replace it. It's relatively easy to replace and I don't think it is as expensive as the motor mount.

deanyel · #3 07-09-2008, 12:26 AM

Motor mounts should be replaced in pairs.

G-Benz · #4 07-09-2008, 03:10 PM

Quote:

Originally Posted by deanyel

Motor mounts should be replaced in pairs.

Like brake pads, shocks, tires...and shoes!

dproudfo · #5 07-21-2008, 03:25 PM

I'm in the process of replacing BOTH front engine mounts on the E420. As of now I have the passenger side mount replaced (which is the easy one). It only took 2.5 hours, which considering the immense amount of room you have in the engine compartment with the V8

isn't too bad. (Solved 98% of the vibration and now it's easy to tell that the driver's side mount has failed when the transmission is in reverse.)

Now the question is how the hell do I get to the driver's side mount? The only post that I could find recommended that I remove the exhaust or ac compressor in order to get to it from underneath. Does this sound right? There is absolutely not way of getting to it from above.

Thanks in advance!

deanyel · #6 07-21-2008, 03:39 PM

Removing the exhaust pipe is not that difficult - two bolts below are easy, two bolts at the top a bit more difficult but doable. One of the upper bolts is not a straight shot so it's nice to have wobble extensions. Breaking the mount top bolt loose can be a struggle from the top or the bottom - probably easier from the top using a lever against your wrench handle.

dproudfo · #7 07-21-2008, 04:01 PM

Quote:

Originally Posted by deanyel

Breaking the mount top bolt loose can be a struggle from the top or the bottom - probably easier from the top using a lever against your wrench handle.

That's how we were able to get to the top bolt on the passenger side but there is zero room to access it from the top on the driver's side. Is it still possible to access it from below?

deanyel · #8 07-21-2008, 04:11 PM

When the engine is raised it looks a lot better on the top. But it is possible to get it from below - with just the right tools. I've done it with a swivel head racheting box wrench. I would think a swivel head rachet would work too. But the problem from below is that your working at such an angle, and with such force, that the wrench or socket wants to twist off the bolt head, which can be controlled by wedging something between the wrench/socket and the engine - also a pain. And there's a very narrow angle to rachet - probably 6 or 8 degrees. Better to work from the top and rig up a lever.

dproudfo · #9 09-03-2008, 12:25 AM

Just wanted to sum up this post on the replacement of the driver's side motor mount. The job was definitely easier to replace than the passenger side. (Maybe I just got lucky)

Pull the front exhaust section (4 bolts) and use extensions and a swivel socket to loosen the bolts on the motor mount. From there you need to loosen all 4 bolts on the actual bracket that's attached to the engine block and remove 3 of them in order to swivel the bracket up and remove/install the new mount. Piece of cake! Total time is approx: 1 hour to 1.5 hours.