Drilled holes on break discs filling up and causing brake fade

NickS1984

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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...
 

Bellow

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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.
.

Sounds more like the pads are 'glazing'. Not fade as that is a high temperature phenomenon, and holes filling with dust isn't helping - other than possibly providing a clue to the problem.
 
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NickS1984

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Sounds more like the pads are 'glazing'. Not fade as that is a high temperature phenomenon, and holes filling with dust isn't helping - other than possibly providing a clue to the problem.

Thankyou for your comment. Why would the pads constantly be glazing? Is there or could there be a mechanical reason for this? If they are glazing, which is a valid suggestion, surely there must be a reason why
 

Mactech

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I have the same car without issues. As your problem started with the change of pads, I think that is the first place to look.
The discs holes aid cooling, but should not be clogging with pad material, which indicates that the pads are defective or simply the wrong material for the application...despite being fitted by a Mercedes dealer.
Brakes can be very fickle things, the wrong surface finish on the discs, the wrong cleaning solution used or a duff set of pads can all have similar results.
If your dealer is not helpful you maybe better off just getting a new set of pads fitted by a well respected Indie....who uses the correct pads.
 

whitenemesis

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IIRC one of the tasks listed in WIS to be carried out at routine servicing is to clear out the disc perforations.
Pretty sure this is never done, certainly never done on any of my Mercs
 

Bellow

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Thankyou for your comment. Why would the pads constantly be glazing? Is there or could there be a mechanical reason for this? If they are glazing, which is a valid suggestion, surely there must be a reason why

Glazing is usually caused by continual light applications of the brakes and the loss of braking isn't really noticed. Then, after a heavy application, the glaze is removed and the familiar 'bite' is restored. I think this is what you are noticing.

Mactech's advice post#5 is spot on.
 

renault12ts

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Try ceramic pads...the holes will not fill up then.

Though, as you've been advised on the other side, the holes are largely cosmetic (but with some aid to cooling) but will not give the symptoms you describe it filled.

BTW...if you had brake fade...you'd know all about it!!!
 

grober

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There are 8 brake pad variations and 6 disc variations listed on EPC meaning the chance of getting the wrong combo fitted are quite high. The Merc dealer should have been able to ascertain which combo applied to your chassis no from WIS but it seems its normal dealer practice not order non common parts in advance for jobs. Usually if required or not in stock they are an overnight delivery from MB central stores but sometimes parts can be on back order or there is pressure on ramp occupancy or the customer is champing at the bit meaning they fit what's at hand/available locally in a "close but no cigar scenario" .
 

Will

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Careful use of a suitable sized drill bit and use of a pressure washer usually takes care of blocked holes on drilled discs.

But regards the lack of performance - you have to retrace your steps to where it went wrong? Pads, surely worth ruling those out as already advised :)
 
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NickS1984

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I have the same car without issues. As your problem started with the change of pads, I think that is the first place to look.
The discs holes aid cooling, but should not be clogging with pad material, which indicates that the pads are defective or simply the wrong material for the application...despite being fitted by a Mercedes dealer.
Brakes can be very fickle things, the wrong surface finish on the discs, the wrong cleaning solution used or a duff set of pads can all have similar results.
If your dealer is not helpful you maybe better off just getting a new set of pads fitted by a well respected Indie....who uses the correct pads.

Thanks for your comment. Unfortunately I think that you may be correct, but I will be pursuing Mercedes to change them before I do it myself, considering the cost. For how helpful they have been so fat, it may come to it though.
 
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NickS1984

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Thanks to everyone for your help and comments, I appreciate all of them! It looks clear that one way or the other I am going to need new pads, be it original spec (that should be on there now) or even updated ceramic. Its also been a great comfort to know that the holes should not be filling up with dust and that I'm not going mad!
 

Ghost84

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I've found this on my C250. just blast with the jet wash when ypou clean the car.. :)
 

whitenemesis

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On my RS3 i used a small piece of round wood i found in the garage & every few washes just ''pocked'' them clean with that.
Doesn't that push the debris into the ventilation spaces?
 

Will

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I think the problem is more the fact that they are clogging up so quickly. This has never been a big issue on the majority of cars I’ve had with drilled discs, certainly not as regularly as it seems for the OP?
 

Continental

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I found on my w203 the latest Pagid pads supplied by MB to be overly aggressive and way too much brake dust absolutely everywhere rims looked black all the time.

Switched to brembo pads and discs BUT made sure to clean up the brake shims from the pagids and use them on the Brembos. Much happier now.
 

Gazwould

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Exactly my experience , I wondered what make of pad could produce so much dust .

2019-06-05 06.45.07.jpg

I was washing the wheels three times a week despite doing low mileage .

Off they came and they're Pagid .
 

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