I think there is usually a change in noise/vibration/feel from loaded to unloaded. Might be it's too subtle to differentiate. Otherwise I am inclined to agree with subierubieroo on the vast majority of time it is probably outside the driveline. The fact your driveline was serviced immediately beforehand points at the driveline and in your case possible indexing.
Mercedes driveline rumble
- Thread starter OM605
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JHZR2
Staff member
I’m assuming this is an older MB diesel?
Keep in mind that the u-joint and alignment of driveshaft is different in these cars. So looking or feeling for slop isn’t necessarily an indicator.
There aren’t two u-joints in these designs, transferring the energy between different heights. Ideally the engine, transmission, csb, and differential are all on exactly the same plane. If they aren’t, the one joint allows for a bit of misalignment, but it isnt designed for that in the long term. So you need to ensure everything else is spot on first.
There’s also a center support bearing that can have a bad mount.
But usually it’s attributed to wheels/tires/suspension rubber.
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JHZR2
Staff member
Given the use of only one joint, and the relative locations of the components, this is true. A bad engine mount, which on these cars tends to manifest on only one side, means that there can be a lean and a resultant misalignment. The u joist should be a passive, non functioning device in the basic design of this driveshaft. If things are misaligned between the engine and diff, then it will be in play, different from a typical two joint setup.
JHZR2
Staff member
Should be in FSM, 41-100. Pretty standard across the range.
I don’t know how the mechanic could admit error if they didn’t pull the shaft and re-verify the marks.
He made a mark with a pencil and was probably sloppy when reinstalling the driveshaft. He admitted not knowing about the aforementioned marks and i showed him the picture. He told me having a lot of experience with BMWs and their driveshafts seem to have a master spline or so he told me, and he doesn't know much about MBs.
Update: I have tried unbolting the engine mounts, trans mount and carrier, roll the car back and forth and re tighten but nothing happened. The mechanic says it could be a wheel bearing or CV axle but as i understand, a CV axle would only cause a vibration under load. There's a bit of play at the transmission output bearing too...
Can you lift the car up and run it while off the ground? Maybe see if something stands out while its turning.
I just did this with my little Mazda truck because I am also fighting a vibration. With the truck in the air and idling in first gear I can see the rear of the driveshaft has noticeable run out. Going to yank the driveshaft and take it to a drive line shop and see what they say.
I just did this with my little Mazda truck because I am also fighting a vibration. With the truck in the air and idling in first gear I can see the rear of the driveshaft has noticeable run out. Going to yank the driveshaft and take it to a drive line shop and see what they say.
You’ve tried unbolting engine mounts, but have you simply replaced them? I may have missed that, but I only saw a trans mount replaced. Engine mounts would be high on my list of suspects if they’re original.
I've replaced them as well. Something wrong with the u-joint is on the top of my list right now, even if it seems to move freely. Out of the hundreds of threads i've read on the internet, it looks like people experiencing the same issue had to replace the u-joint. I don't know if it's linked but it's been raining almost non stop for months here and i did not drive the car much. Moisture + modified angle since installing the new parts might have done something.
Problem found! When i thought about giving up i decided to give the rear (new) flex disc a look which was a shot in the dark and understand how it works, then i saw this video:
This is was happened to me, the driveshaft was pushing on the soft portion of the flexdisc. Decided to turn the donut to install it correctly but the metal inserts were pushed when the mechanic installed it the wrong way. Bolting everything again kind of pushed the inserts back as they should be but the flex disc is still not 100% straight.
I'll keep an eye on it but 80% of the vibrations are gone and it drives like a Mercedes again! Big lesson learned, originally didn't want to do the job since i had to do it on my back under the car. In the end all was done wrong, driveshaft alignement, flex disc installation and it caused me a month of headhaches just to redo everything myself again. I don't know how he screwed this one up, this isn't rocket science.
This is was happened to me, the driveshaft was pushing on the soft portion of the flexdisc. Decided to turn the donut to install it correctly but the metal inserts were pushed when the mechanic installed it the wrong way. Bolting everything again kind of pushed the inserts back as they should be but the flex disc is still not 100% straight.
I'll keep an eye on it but 80% of the vibrations are gone and it drives like a Mercedes again! Big lesson learned, originally didn't want to do the job since i had to do it on my back under the car. In the end all was done wrong, driveshaft alignement, flex disc installation and it caused me a month of headhaches just to redo everything myself again. I don't know how he screwed this one up, this isn't rocket science.
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Surprised that any experienced, or competent Euro mechanic would make that mistake.
Being european wasn't enough here.
