Mercedes W212 Shudder

Tomorrow's a big day. It's not my birthday. It's not a holiday. It's not even your birthday (unless it is, in which case, happy birthday!). It's... the first time I visit a Mercedes-Benz service department.

Did I just buy a Benz? Nope. We've had this 2012 E350 now for like 6 years. This is simply the first time that the car will visit a Mercedes dealer service department under our ownership. Everything else just gets handled at our local private shop.

It's going in for a nasty vibration or shudder that it's been experiencing. I want to know if any of you have experienced something similar or if you have any ideas. Here's what I've noticed:

• It happens when the engine is at lower RPMs.
• It usually occurs when the accelerator position is increased, but not enough to cause a downshift. For example, when starting up a hill.
• RPMs wiggle around just a little bit, when it happens, but the wiggle might be the torque converter lockup (if it even does that).
• The shudder lasts about 3/4 of a second.
• You can definitely feel it, but it is also quite audible as the whole car vibrates.
• The transmission shifts fine, doesn't slip at high power settings, and the CEL is not illuminated.

I had been thinking that something was up with the transmission. The dealer told me that there is a flush that they recommend around the ~90,000 mile mark. We're right around there. Maybe there is something going on there. But perhaps the driveshaft, or a coupler, or a CV is to blame? The car is RWD. It also continues to pass state inspection, so it might not be the CVs because I assume they'd spot that issue. The local shop recommended I take it to the dealer.

So, what do you think?

Not sure what it is but that's not CVs or a driveshaft. CVs tend to get a little play in them and make clicking noises until they break apart, driveshafts tend to make chirping noises and have vibration in specific speed ranges when the U-joints wear out. This sounds like it's transmission-related or possibly engine-related.

Thank you for chiming in! I wonder if the car uses those rubber donuts to join the drive shaft to the transmission or differential, or if it has a center support bearing? Those were the sorts of failure points I had in mind. I've never had a car where one of those failed, so I'm not sure how to recognize the symptoms. I'll find out tomorrow anyway!

Thanks! 

That *might* but those rubber donuts? What do they call 'em.. guibos I think. But I haven't had any donut failures here yet. 

My Merc w126 had two Giubos, one on each end of the driveshaft. My take is that they are not your problem if its so sudden and it goes away so quick. 

Bad engine mount?  just guessing

The service manager and I just took it for a drive. We are both kind of thinking that it might be the drive shaft support bushings. They will diagnose it for me today and let me know.

We do believe the engine mounts are worn, but we don't think it's causing this specific problem. We'll cross that bridge another day.

So we're back to what I originally thought was wrong with the car--way back when this started occurring--the transmission. The technicians inspected the car and they believe the torque converter and trans need a flush, and that the shift solenoids should be bled. We're going to give it a go and see whether it comes around. If this is really the problem, then this is very good news because this is significantly less-expensive to perform than a driveshaft replacement. Of course... if this is the problem, but flushing it doesn't fix it, then there may be a 2012 E350 up for sale in the Cars for Sale forum for completely unrelated reasons...

In the meantime, I'll continue to drive the fastest vehicle I'll ever drive (i.e. the loaner) until tomorrow evening.

That's what a slip/sticking torque converter clutch feels like.  It's almost like an engine misfire.  Have fixed many with BG fluid/additive.

I am not sure what "bleeding the solenoids" means, they are kind of self bleeding.   If they are doing a flush that includes a cleaner stage (like the BG process) then he may mean that they exercise the solenoids while the cleaning solution is in the fluid, which is not a bad idea.  (I usually would just run 'em up the road and back, if the job timing worked out)

Yep torque converter clutches not fully engaging.  Had an old Mercury DisSable that would do exactly this when climbing big grades in lockup until the trans warmed up.  It would throw a code for TCC Applied Clutch.  Like clockwork.  If this is the same 722.9 ZF trans the rest of the E-series got, a new torque converter is not particularly expensive or hard to replace.  Even a full used trans is a single stack of high society and you can swap it out in an afternoon.