1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

GLA gearbox/drivetrain 'shunting' - what did they do?

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by sidewaze samm, Oct 14, 2019.

  1. sidewaze samm

    sidewaze samm Member

    Messages:
    24
    Likes Received:
    1
    Joined:
    Jun 12, 2012
    Location:
    greater manchester
    Your Mercedes:
    '14 GLA 250 4matic
    My car is a GLA 250 4matic auto, 2014, 55k miles.

    Over the past two months or so I've noticed symptoms that are getting worse (or I'm becoming more aware of...). When driving at a constant slow/moderate speed (say, under 25mph) I feel and hear what I can only describe as 'shunting' in the drivetrain. It seems to come from the centre of the car to the rear somewhere - not from the front. The noise/feel is subtle and disappears in the increased road noise at higher speeds. It is linked to road speed and at constant speed is fairly regular, but not totally. It just feels like there's a tiny amount of slack in the drivetrain that is being taken up and then relaxed again, even at steady throttle opening on a flat road.
    [​IMG]

    So now the odd thing...
    Four days ago, I went in to MB for MOT and mentioned this to them. I asked whether someone could just drive round the block with me, to advise whether there is an issue or whether "they all do that". (I've had the car for nine months now).
    My car goes off to the workshop for MOT, and returns two hours later. I'm told the technician took it for a test drive and could see no problem. "Sorry sir, but we're much too busy now for the technician to go out in the car again with you..."
    So, somewhat bemused, I drive home thinking "the car will be due a service before Christmas when the warranty runs out, so I'll take it somewhere else".

    But on the journey home and in the week since, there has been no repeat of this shunting issue, None at all. [​IMG]

    So anyone got any ideas on what they did to my car ? I just do not believe it's a simple coincidence.

    cheers
     
    Jim2 likes this.
  2. malcolm210

    malcolm210 Senior Member

    Messages:
    3,637
    Likes Received:
    656
    Joined:
    Aug 21, 2005
    Sounds propshaft/driveshaft related the tech may have found one of the couplings slightly loose an easy fix 5 min job
     
    Jim2 likes this.
  3. John Laidlaw

    John Laidlaw Senior Member

    Messages:
    21,593
    Likes Received:
    6,127
    Joined:
    Nov 15, 2013
    Location:
    Wirral
    Your Mercedes:
    UnMercs BMW i8 Volvo XC90
    Do you normally do a lot of stop start town type driving?
    Suspect the tech gave it some beans on the open road..
    However, check with them (or your paperwork/service history) whether the ATF has been changed or due to be.....
     
    Jim2 likes this.
  4. OP
    sidewaze samm

    sidewaze samm Member

    Messages:
    24
    Likes Received:
    1
    Joined:
    Jun 12, 2012
    Location:
    greater manchester
    Your Mercedes:
    '14 GLA 250 4matic
    That was an initial thought - but I was told very clearly that the tech took it for a spin and found nothing wrong. If something was done (bear in mind the car was having its MOT) then why not mention it?
    Conspiracy theory - is there a related issue that MB would rather people didn't know about?
     
  5. OP
    sidewaze samm

    sidewaze samm Member

    Messages:
    24
    Likes Received:
    1
    Joined:
    Jun 12, 2012
    Location:
    greater manchester
    Your Mercedes:
    '14 GLA 250 4matic
    Yes I spend a fair bit of time on local, rush-hour driving. But I'm also known for using a fair bit of the 200bhp, and regularly use motorways too...
    Isn't the gearbox supposedly a sealed for life affair?
     
  6. ajlsl600

    ajlsl600 Senior Member

    Messages:
    3,450
    Likes Received:
    1,291
    Joined:
    Nov 18, 2013
    Location:
    france
    Your Mercedes:
    clk3202001,sl6002003 with everything,A class 170cdi auto
    bizarre was thinking something to do with the TC . but if it went away ? anyway i would confirm yr visit ,yr request ref this issue in writing and request an in writing reply. send it recorded delivery. as you say warranty soon out and if no proper record you leave yrself open to "no one said anything, we dont know anything about the matter "
     
  7. OP
    sidewaze samm

    sidewaze samm Member

    Messages:
    24
    Likes Received:
    1
    Joined:
    Jun 12, 2012
    Location:
    greater manchester
    Your Mercedes:
    '14 GLA 250 4matic
    My thoughts also. I've now booked the car in again, as the engine management light has come on now...
     
  8. LostKiwi

    LostKiwi Senior Member

    Messages:
    20,403
    Likes Received:
    9,964
    Joined:
    Aug 25, 2006
    Location:
    Midlands / Charente-Maritime
    Your Mercedes:
    '93 500SL-32, '01 W210 Estate E240, 02 R230 SL500 (Malcolm Spec), 04 Smart Roadster Coupe
    MB gave up on that theory years ago.
    Depending on the box it may be 37500 miles between services or more. None are sealed for life.
    All that meant in the old days was "Sealed till it dies", usually at great expense to the final owner.
     
  9. ajlsl600

    ajlsl600 Senior Member

    Messages:
    3,450
    Likes Received:
    1,291
    Joined:
    Nov 18, 2013
    Location:
    france
    Your Mercedes:
    clk3202001,sl6002003 with everything,A class 170cdi auto

    doubt that policy bothered benz much as averages would have them all out of warranty.
     
  10. John Laidlaw

    John Laidlaw Senior Member

    Messages:
    21,593
    Likes Received:
    6,127
    Joined:
    Nov 15, 2013
    Location:
    Wirral
    Your Mercedes:
    UnMercs BMW i8 Volvo XC90
    As above sealed for life was a flawed policy, needs ATF changes like every metal mechanical part, simple !
     
  11. OP
    sidewaze samm

    sidewaze samm Member

    Messages:
    24
    Likes Received:
    1
    Joined:
    Jun 12, 2012
    Location:
    greater manchester
    Your Mercedes:
    '14 GLA 250 4matic
    Update -
    So, I've finally got the car booked in for service and for this vibration to be looked at. Again.
    This time I went for a drive with the tech - and he agreed with me... a subtle, irregular, speed-related vibration from the rear.
    Left the car with them overnight and have just received a call telling me the cause is my front tyres - cracking slightly in the tread (not bad though, as it's only just been through MOT), and I need new front tyres! Current tread depth around 4mm+ with even wear.

    Really!??

    I'm struggling to believe the small cracks in the tread will cause any issues at the moment at all, let alone a 'chunking' from the back end (nothing present in steering or at front end at all).

    Any opinions?
     
  12. malcolm210

    malcolm210 Senior Member

    Messages:
    3,637
    Likes Received:
    656
    Joined:
    Aug 21, 2005
    Are the wheel fitments staggered if not swap the tyres front to back and see what difference it makes.

    From your description of the fault it could be a 4 wheel drive issue



    The vehicle usually drives from the front wheels and the rear axle electronic clutch only operates to provide 4 wheel drive when conditions dictate, it may be this clutch operating that you can feel especially if it’s faulty and the conditions don’t require it
     
  13. Wighty

    Wighty Senior Member

    Messages:
    7,319
    Likes Received:
    4,397
    Joined:
    Aug 4, 2016
    Location:
    Sunny Essex
    Your Mercedes:
    W211/E320cdi/2009 and CLK200k 2009
    Sounds like you will be out of pocket for 2 front tyres when you next take the tech for a drive round the block . To find the same problem .
    Keep the 2 tyres when they change them ?
     
  14. Blobcat

    Blobcat Moderator

    Messages:
    17,339
    Likes Received:
    4,936
    Joined:
    Feb 8, 2006
    Location:
    Near Grange Moor (not Wakefield...)
    Your Mercedes:
    R171 SLK280 3.0, Land Rover 110 County SW
    Very much doubt it’s due to small cracks in the front tyres.
     
  15. Botus

    Botus Senior Member

    Messages:
    3,253
    Likes Received:
    675
    Joined:
    Jul 29, 2014
    Location:
    UK
    Your Mercedes:
    S500/2010/500
    I can imagine its the same issue as as other models, a result of fantastic (ly bad) engineering when they created the RHD versions

    the GLC is well known for shredding its tyres and making the owner look like an embarrassed fool. It becomes more prominent as the weather gets colder. They mask with a set of free all season tyres. Its to hide the fact the steering geometry on a lock is nothing like it needs to be (or indeed is on LHD cars)
     
  16. Botus

    Botus Senior Member

    Messages:
    3,253
    Likes Received:
    675
    Joined:
    Jul 29, 2014
    Location:
    UK
    Your Mercedes:
    S500/2010/500

Share This Page