A-Class - W169 - Heavy vibration when accelerating.

shaungjones

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Hello and thanks in advance for any suggestions with regard to this issue.

Our A-Class 160CDI SE has now competed some 112,000 miles and is 06 registered.

I regularly swap from summer to winter tyres.

In late April we switched back to the summer set of tyres and soon afterwards began experiencing a heavy vibration through the car if we accelerated hard.

I have had the Star read out performed and no codes are showing.

My garage has checked all the usual areas, engine mounts, wheels and tyres etc and the report is all OK.

They have a wish to check the passenger side drive shaft but I have put off spending more money on diagnostics until I shared this with all Mercedes Club forum users.

The fuel consumption is normal. Just the driving experience is poor. Pick up seems sluggish - you have to really put your foot down. On an incline the vibrations seem worse. There doesn't seem to be a speed or gear being used that shows the problem over any other time.

The car is feeling like a bag of nails and I wonder if any other owners have experienced this problem ?
 

grober

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Have you got the CVT transmission? Lots of problems with these at high mileage - torque convertors for one.
 
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shaungjones

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Yes we do have a CVT gearbox. It has already had some electronic speed sensors replaced because the originals went hay wire.

How could we determine if "torque converters" were the fault ?
 

WG M-B

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It does sound like a possible tic fault. If you find a garage with star diagnosis equipment they can switch off the Tc lockup clutch and test drive
 
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shaungjones

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Can you just expand "tic fault" please ? To check, are you suggesting turning off the traction control and lockup the clutch ? On a test drive what symptom are we looking for to prove the tic theory ?

Thanks so much for responding.
 
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shaungjones

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So far as I can tell my MkII A-Class with CVT gearbox does not have a dual mass fly wheel.

The forums tell me they show problems on cold start and that is not the problem I am experiencing.

Thanks for your suggestion.
 

grober

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The gearbox has a form of clutch and a torque convertor.They sort of combine together to lock up the transmission drive controlled I believe by a solenoid valve driven via the CVT electronic control unit. While the phrase "lock up clutch" sorta conveys the impression this clutch is either engaged or not it is actually programmed for "slippage " to minimise driveline vibrations at certain rpms. You can imagine that such an arrangement might be prone to wear and that any malfunction of same might give risen to vibration in the driveline. In the test mode W-G MB refers to I imagine that this clutch activation/slippage can be defeated temporarily in order to test whether this is the source of the problem? Chances are you may need a new Torque convertor assembly- part of the logic being if you are costing the labour of removing and part stripping such a box- then complete replacement may be the best option for long term repair.
 
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shaungjones

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Very many thanks for the explanations.

In my analysis I would not say that vibrations occur at certain rpm's - simply put - if you demand a spritely period of acceleration currently the car shakes pretty much throughout - especially if on an incline. As soon as you ease off the accelerator the vibration stops. Even change up of gears in such a sequence doesn't change the vibration one bit.

This maybe why my garage are minded to check the passenger side drive shaft.

As background the car has had one drive shaft replaced - the longer one after the original simply snapped off at the gear box side.

Are there any instances of such driveshafts causing vibrations ?

If you drive steady I have no issue with the gear change so I am hoping it is not the gear box but all these pointers provided give me more ammunition to discover what may have gone wrong.
 

WG M-B

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Sorry it meant to read Tc
If the Tc is deemed to be at fault then you can renew the trans fluid and filter and add some secret magic juice to try and stop it;)
 
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shaungjones

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This all sounds very interesting. Thanks.

Using the Star machine you suggest we can turn off the tc (torque converter) lock up clutch.

Then do a test drive and see if the vibration is still felt - if not then most likely this is the fault.

With the tc lockup clutch off how is the gear change likely to be - very clunky ?

Secret magic juice - prey tell ??

I have two actions, one to phone Mercedes Customer Help line to see if they have any suggested action and call Chester Automatics in Sandycroft who may be willing to assist.
 
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shaungjones

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I am very pleased to advise that the problem has been solved.

I got agreement from my independent garage to remove and inspect the near side drive shaft. They also quoted for an aftermarket replacement.

Yesterday they were pretty happy with the incumbent and were puzzling over what to do next. They also removed and looked at the offside driveshaft (replaced by Mercedes main dealer at 70k miles). They did note a small hole in one of the rubber bellow covers and had ordered the part.

Today there was a further review of the near side driveshaft and finally it was observed that a bearing may have dropped and caused a groove to wear - this looseness was most probably the source of the vibrations.

So a new nearside driveshaft was fitted and problem solved. Thanks for all contributions and I hope my experience helps other A-Class owners.:)
 

grober

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I am very pleased to advise that the problem has been solved.

I got agreement from my independent garage to remove and inspect the near side drive shaft. They also quoted for an aftermarket replacement.

Yesterday they were pretty happy with the incumbent and were puzzling over what to do next. They also removed and looked at the offside driveshaft (replaced by Mercedes main dealer at 70k miles). They did note a small hole in one of the rubber bellow covers and had ordered the part.

Today there was a further review of the near side driveshaft and finally it was observed that a bearing may have dropped and caused a groove to wear - this looseness was most probably the source of the vibrations.

So a new nearside driveshaft was fitted and problem solved. Thanks for all contributions and I hope my experience helps other A-Class owners.:)

Glad you got the problem solved-- lot cheaper than an torque convertor problem.:D
 

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