Hello all!

I need some fresh eyes on this one and ideas on what could cause this.

Low milage absolutely mint 2010 c250 coupe (i know there is a coupe section but that one is dead and this is not related to body style).

Car has done about 37 200 miles. There is no sounds or any other issue present. No codes, car runs fine, pulls as it should, good mpg etc. Everything looks like new.

About 6000 miles ago i started to have vibrations between 55 - 60 miles, shaking the steering wheel, pedals and seat. Just like when you have unbalance in a wheel. Nothing else out of the ordinary.

Since then and over time the vibration have gotten worst. Still vibrates the steering wheel, pedal and seat shaking but first it started to come at higher speed past 60 miles, then also at lesser speeds. Now i can feel it as in more or less all speeds and at ideal in all gears (D, R, N, P). Car feels horrible to drive, like it what to pull it self apart at high speed and almost skipping down the road at low speed.

Things I have done so far with more or less no change; oil and filter service, sparkplugs, air filter, front thrust arms, checked and adjusted front wheel bearings, checked rear wheel bearings, replaced prop shaft flex discs and support bearing, diff fluid change, transmission service, brakes all around, engine and trans mounts, checked all suspension components without finding anything. Still having no other issue, no noises, rattles, car runs fine.

Now 4 cyl vibrates quit a lot but i do think i might have excessive engine vibrations. I have looked for vacuum leaks without result, without being ang expert I've looked at live data while driving with no result. Tomorrow I'm going to try running the engine without accessory belt just to rule out any pulleys but after that i am out of ideas. Any suggestions? Also I'm thinking that ignition, fuel and vacuum leaks could cause vibration but should that not trigger any codes by now? Or have an effect on how the engine performance. As said before, pulls fine and good mpg.

 

@Dokus - Hi, after reading your post my best recommendation is to isolate if it’s either an ENGINE vibration issue. Or, a DRIVE LINE/SUSPENSION issue.

Youre all over the place and it’s hard to make any specific recommendation on what to check next.

I would recheck all the work you said you have done. Ensure everything is tight and no bolts or nuts are missing.

I had a slight steering wheel shake on the highway when I first got my c250. Ended up being the front rotors.

seeing as you’re saying it is now happening in all gears even at idle, I would look to and engine issue. But, definitely try and isolate.

maybe a clogged PCV system or EGR?

Keep us updated!

ant

 

These car do have a tendency for the accessory belt tensioners to fail. Before you remove the accessory belt just start the car and take a look at the belt tensioner, it should be stable and smooth, with barely any movement. If it is vibrating, shaking or bouncing around it needs replacing. And yes, it can impart quite a bit of vibration into the car, but not usually to the degree your describing.

Have you had the wheels checked to see if you have a buckled rim on one or more of the wheels?

 

Check wheel balance. A screw/nail in the tire could cause it even without losing air. Also bent wheels.

 

I am 100% behind this, the thing is you need to start at the very basics first.
37k milage is low so I dont expect most of the items you have replaced.

 

As written above you need to isolate if this is... wheel/engine/tranny/prop-shaft/...

I just got done dealing with front wheel vibrations at 60mph. It was caused by ball joints + loose bearing freeplay.

Proceed by elimination...
If this is engine/tranny aged rubber mounts... then it won't vibrate front wheels!

 

Thank you. I'm sorry but I must have not been clear. Everything mentioned have already been checked or replaced. Of course I could replace all control arms and bearings but I have find no play. The vibration does not change with rpm or turning, only speed.

The tensioner does move a little. Removing the belt does reduce the vibrations by a tiny amount.

The idel vibration is mostly gone. The vibration at speed is still there but better after replacing all parts mentioned above.

I suspect transmission or differential. Flexdiscs and support bearing made a huge difference on vibration but it's still there, just less due to all the new rubber.

I've also checked everything bolt I can find and get to, nothing is loose.

Thanks for the ideas anyhow

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After reading my own first post I see I have been very unclear.

I did wheel balance and alignment, new tires, tried different wheels before above. After no result and finding no faults I've been replacing parts that could cause vibrations.

 

Got some more clues to go on as new problems have presented themselves.

Yesterday morning at start when rolling I got a loud whine. Went away after a short time. Same after leaving work.

Since then the whine comes and goes at lower speed but always present at higher speed, say 50 mph and above. The whine randomly varies in volume. It's not very loud now, more like a humming. It's not rpm or gear dependent. Revving at idel, no whine. If I coast the whine decrease in volume, with acceleration it increase to some extent but then stay on the same level of noise

Gearbox shifts fine, no stuttering or similar. Everything is working fine. Expect that I still have the vibrations. Also, from time to time and also when standing still a clapping or knocking noise have randomly start to appear. Sounding like it's coming form the middle. Also not rpm or gear dependent.

Since it's not rpm dependent and only appear at speed other than the knocking which can come also when standing stil I start to suspect the transmission or tourqe converter.

Thoughts?

A few times before I've heard the knocking but it is much louder now. I've changed the transmission fluid with the FCP euro kit. Fluid looked good. Very little metal on magnets.

 

Hi,
Is your 250 rear drive or a 4wd Mercedes?

Do you have a garage that can lift the car and when the wheels are up, you start it and drive it through the gears to see if you could recreate the sound then the engineer investigates it from underneath?

 

Rear wheel drive.

Did some more investigation today. The whine or humming is there now even when idling but it's very very faint. Using a stethoscope I can here the whine is coming from the transmission. The whine is increasing while driving up to a certain level then just changing if I accelerate or not.

Vibrations are randomly increasing or decreasing at speed above around 50 mph but has settle down quite a lot since all the new rubber parts.

Before deciding on a new transmission, have anyone tried additives in the 7g tronic such as liqui moly 5135 or instant shudder fixx?

 

Shudder fix or a fluid conditioner might help if the vibrations are coming from the torque converter. But they don’t fix anything. They just change the friction characteristics of the fluid a bit to cause damaged converter clutches to work smoother for a while.

Just off the top of my bald head since I can’t get my hands on your car, vibration may be the converter and whine or hum may be the front pump. Neither of those is a fatal transmission failure. But I won’t give you any more than 50% chance of that being correct. The converter could be a bit expensive, but only requires dropping the transmission to replace. The front pump is not expensive or particularly labor intensive but does require bench service on the transmission.

My reason for the low probability is the very low mileage on your car. I’ve never seen a W or X204 with a transmission or converter failure at 37k miles.

 

Can you get vibrations when you sit in the car doors and windows closed in park or neutral through out the revs?
I would run it all on the 2 post hoist with someone looking at the drive shaft, trans and engine to see it it can be replicated and then at certain rpm held there until it has been identified.

I don't think it will be tyres , wheels, driveshafts or transmission and also the torque converter I would be extreamly surprised if it had any issue.

Have you had the engine scan tested?

 

Vibrations only while moving at highway speed.

Whine with various degree at all speed coming form transmission.

I ran the car on jackstands but could not get enough speed without runing a risk of falling off. Sure I could get in on a lift.

Other than the transmission the diff, halves shaft or wheel bearings could cause this issue. The vibration or whines does not change while turning left or right. No codes, no indication of anything wrong other than whine and vibrations.

Only reason I'm thinking transmission is due to the whine.

 

Well. The sound have been getting worse and I do not think it's the trans anymore but rather the diff.

Whine in varying degree at all speeds above 20 kph.

Worst when could, very loud the first 20 sec at start then it settles to a lesser more stable whine.

If I drive at freeway speed and take my fot off the gas the whine becomes less. Gas and it becomes louder.

If I switch to neutral at highway speed the whine goes away.
Vibrations also decrease.

Does this sound like diff issues to you?

 

This is from a cold start

 

For others with the same noise. The issue was a faulty center support bearing. The noise only came when the car was sitting outside making me not notice it at first.

So that is solved.

I still have the vibrations, but after replacing all the parts mentioned above it's very minor. It only occurs above 60 mph. The vibration decrease when I turn the steering wheel just like bad wheel bearings. I have already replaced the front ones which made no difference. I don't think it's the rear ones. Vibrations comes in the steering wheel, pedals and a little in the seat. Similar to an unbalanced wheel. I've already tried two sets and are out of ideas. Any suggestions?