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Drilled holes on brake discs filling up and causing brake fade

Discussion in 'Suspension, Steering & Brakes' started by NickS1984, Aug 13, 2019.

  1. NickS1984

    NickS1984 New Member

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    2016 GLE 350d AMG Line Premium Plus
    Hi there! I'm hoping that someone can please help me....
    I have a 2016 GLE 350d, and in March took it to my local Mercedes to have new brake pads. The first pads were great, stopped the car like you wouldn't believe, these new pads however have been a nightmare. Every 600-700 miles maximum the drilled holes on the discs are filling right up with brake dust and as they fill up the pedal becomes less responsive and the bite moves further down the pedal leaving a period of travel on the pedal before braking starts. I've taken it back to Mercedes, who have bled the brake lines again and they are saying theres no problem - but there is! Its brake related, and I worry having my 2 young children in the car that eventually they will just do nothing.
    The old pads never caused those holes to fill up ever, so it must be related to these new pads somehow, I just have no idea how.
    Could it be poor, cheap or faulty pads? Have they messed up the install? Please help me....
    The one thing that strikes me is that if I brake hard, I mean emergency brake, it gets a little better temporarily before returning back to how they are.
    I really am lost, I know theres a problem, and I know it isn't right, I just need a little direction from someone who knows what this is or may be.

    Thankyou in advance for any help...
     
  2. Blobcat

    Blobcat Moderator

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    Hello and welcome

    When was the brake fluid last changed? If over 2 years ago get it changed
     
  3. OP
    NickS1984

    NickS1984 New Member

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    Hello Blobcat. Thankyou for your message.
    It was done, again by Mercedes, 16 months ago. The dealership checked that before they bled my brakes again and said it was fine.
    Its like there isn't enough pressure being applied to the pads and discs to create the gas to keep the holes clear and so they are filling up decreasing the braking effectiveness. I know when they are filling up cause I can literally feel it in the pedal and how the car brakes.
    Do you have any other suggestions as to what this may be please?
    Many thanks
     
  4. Blobcat

    Blobcat Moderator

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    How are you (or your garage) cleaning the holes? I’ve had them fill with rust on cars before and spent an hour or four drilling them out with a 4mm electric drill (battery ones go flat too soon...)

    The only reason there won’t be sufficient pressure is if there is air in the brake fluid from previous overheating of the brakes. Which If they’ve bled the brakes they suspect or found a spongy pedal.

    If they’ve tested the fluid moisture content and it’s below the level to change then your next option is change the pads and possibly the discs at the same time.

    I had a brake imbalance earlier this year which you couldn’t really feel. The discs and pads had some marks and discolouration on (probably from very hard sustained braking). The cure was new pads and discs (and I had the fluid changed at the same time).

    Depending upon how you brake you can “cook” the discs which seriously impacts on braking performance.
     
  5. LostKiwi

    LostKiwi Senior Member

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    The holes filling won't cause brake fade under normal usage. Drilled discs areca styling gimmick on most road cars.
    It sounds to me that the new pad material is inferior to what was originally fitted.
     
  6. carlls

    carlls Senior Member

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    hi and welcome
     
  7. AMGeed

    AMGeed Senior Member

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    As above, the holes filling with brake dust won't reduce your braking effectiveness.

    I suspect the pads may be glazed, thus reducing braking power.
     
    stwat likes this.
  8. Dean Fletcher

    Dean Fletcher Senior Member

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    Hello and welcome. I had this when changed over to brembo brakes. Eventually they did start to work and there the best brakes iv bought. I have a feeling that your new pads ain't up to the task.
     
  9. OP
    NickS1984

    NickS1984 New Member

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    I cleaned the holes with an Allen key, as crude as it sounds, and it did clear them well - both the front and rear disc. I then jet washed them clean. The material moved relatively easily and it was definitely only brake dust. There was no rust or anything else present.
    A full disc and pad change would not be cheap, and so it is something I would like to avoid if possible for obvious reasons, but I understand that is the ultimate fix.
     
    Wighty likes this.
  10. malcolm210

    malcolm210 Senior Member

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    I’d look into changing the pads only, Brembo are a good quality option to those fitted at the dealer, it does seem that the pad material has been changed by MB. The only downside is that it will affect your remaining warranty if that bothers you
     
  11. Wighty

    Wighty Senior Member

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    An mot test would detail the braking force applied on each axle and may highlight a fault ? It's a cheap test anyway .
     
  12. Blobcat

    Blobcat Moderator

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    That's exactly what picked up on my issue, had the calipers stripped down and cleaned - made no difference so new discs and pads and happy days again :)
     
  13. ajlsl600

    ajlsl600 Senior Member

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    yr right. clean holes find out what previous pads were,go back to them
     
  14. Wighty

    Wighty Senior Member

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    I only thought of it because I tend to read the braking forces on my mot certificate to identify any braking issues , especially as Wighty Garage Services is doing the work :oops:
     
  15. Blobcat

    Blobcat Moderator

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    I do it by lap times :rolleyes:

    I'll have to call into that garage on my travels :D
     
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  16. Wighty

    Wighty Senior Member

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    It's a hard garage to find , no recommendations , cash only , no guarantees , only works occasionally in good weather , very little knowledge base , willing to try out work on other peoples cars first :D
     
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  17. Oldspanners

    Oldspanners Senior Member

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    I've had many incidences of the disc being "blued" after repeated heavy braking (admittedly under competition circumstances) after which no amount of cleaning or pad changes would restore the original braking efficiency or feel. In these circumstances the only cure was a change of discs and pads.
     
    Blobcat likes this.
  18. Blobcat

    Blobcat Moderator

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    Still sounds better than a main dealer :D :p
     
  19. Naraic

    Naraic Moderator

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    Other replies have advised you that the holes are merely cosmetic...but you seem to have ignored those replies.
     
  20. Pullman

    Pullman Senior Member

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    Not sure if this has been mentioned.... Mercedes brake pads are now asbestos free, most car manufacturers are ,, which means they are harder.... think you can still get pads which are softer and more efficient .. not sure if they are completely free of asbestos tho'..

    Sent from my Nexus 5 using Tapatalk
     

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