Hart6

Hi all. I've been chasing two problems with my 05 320CDI recently; a secondary jump/judder when going over bumps, and a highway speed vibration on deceleration.

Had another look under the car today and this time focused on the transmission mount. I'd ignored it before because it looked fine, and certainly hadn't collapsed or anything like I've seen elsewhere. However, I discovered it's quite soft; soft enough that with just my hand I can squeeze it causing the transmission and propshaft to move. With a pry bar it's extremely easy to rock. I also then felt the transmission lever while driving, and sure enough I can feel it wobble when going over bumps or move back and forth as I accelerate/decelerate.

My question is, does this definitely sound like a shot mount? How soft should the mount be to absorb vibration from the transmission? Car is booked in to be looked at in a couple of days, but if people think that this is a potential contributor to either or possibly both issues, then I'm going to cancel and change the mount first.

The reason I think there's a chance that this is responsible for possibly both issues is that both have got worse at the same time, and I can see how a shot mount could cause them. The weight of the transmission moving about could certainly cause some underfoot shudder, and if the propshaft isn't being controlled properly or is out of spec angle wise when there's no drive, then I can see that it would transmit a fair bit of vibration. The flex discs are fine.

Basically I'm just looking for someone to tell me whether or not it's worth giving a go?

tusabes

It’s a common failure item , a necessary maintenance item $39 part and 15 minutes labor so it should definitely be changed as part of ruling out the posdibilities

wallyp

I agree - this is one of the few parts on the W220 that should be changed out of suspicion.

Hart6

Thanks for the input both. I've got one on the way.

Hart6

Just a quick update on this. Changed the mount. As everyone has said, it's a very straightforward job (half a dozen screws holding the undertray, and then four bolts total to remove the mount, jack under the transmission). While it hasn't cured my vibration, it has made a significant different to the overall ride quality, particularly in reducing that feeling of a second bounce through the car. It's worth noting that my mount did look generally fine. A little tired perhaps, but no obvious deterioration. When I compared softness old vs. new side by side I was actually concerned that replacement wasn't going to do anything, but it most certainly did. As other people have said in the past - if you've not changed yours, just do it - even if you don't think there's a problem!