Low, deep "Shroo" sound from rotor when braking, HELP!? :o

[eresseraca]

Kind of annoyed at the van finally thought I had everything except an oil leak fixed and then a new problem is here.

Yesterday driving at city speed and braking all of a sudden a low pitched "shroo" sound appeared from the right side disc brake/wheel well. I've done two test drives since I heard it the first time. It kind of happens randomly it seems, when pressing the brake pedal it brakes completely normally without any feel of uneven pull to one side or the other but the "shroo" sound appears and continues after releasing the pedal, and sometimes goes away when braking the next time or just pushing the brake down lightly a few times.

Drove it some 40km today, both city and highway, no problem but one or two times when braking more intensively the sound appeared again for briefer moments... The noise isn't super loud but still loud enough in city traffic that there's no question that is its coming from the right front and is connected to braking. The sound kind of reminds me of when something (leafs and stuff) would gets stuck in between the mudguard and tyre of a bicycle starting making a continuous 'schooohrooooo', but a lower pitch... kind of static sounding, constant intensity.

Makes me think the caliper sticks to the rotor. But when comparing to the sounds on Youtube videos of a stuck caliper which is more of a scary screeching noise than a low pitched shroo I kind of wonder if it might be something else.

Another thing that I first suspected was a rock or some debris that had gotten stuck in between the pad and the disc, and that it found its way out by itself. But then on my second test drive the sound was there for brief moments again. So kinda rules the stone/debris problem out doesn't it, if it comes and goes like that?

The rotor which I checked when putting the studded tires one a few months ago was nice and even and now when checking after I first heard the noise there's a groove in the disc/rotor. It's about 0,5cm wide and goes evenly around the whole disc. It's rough textured to the extent that if I feel it with my finger it's definitely as if something hard that has scraped/grinded the rotor down all around. (see attached pics)

A rock or something would fit here as well, but that would not explain why I get it only now and then and also why the sound continues after braking when the brake pedal is released.

MOT inspection back in October had no comments on the brakes or their behaviour.

I haven't owned a ton of cars so first question is... should I be worried? Then... Any thoughts on this, help, ideas or similar experiences for any of you guys?

Disc01.jpg

Disc02.jpg

Disc03.jpg

[gotgcoalman]

Is taking the wheel off and "fliping" the caliper to remove the pads an option?
Something is causing the nasty scoring on the disc.
If it had been on the back then I would have said a stone caught between the back plate and disc
but this is on the outer/front.

[cherniy_chack]

I think that you need to remove the wheel and inspect the condition of the brake pads.
Perhaps they are worn down to metal.

[gotgcoalman]

pads down to metal would cause scoring right across the disc.
un even pad vear due to sticky caliper slide pins causes scoring either top or bottom of the disc.
the wear indicates there is friction material on the pads and something harder than feroddo is
comming into contact with the disc at the marked point.

Wheel off spin the hub and listen/look is the best course of action.

[cherniy_chack]

gotgcoalman,there is a very simple way to solve the problem: remove the wheel, remove the brake calliper and pads and inspect everything.
This can take 1 hour.

[eresseraca]

Many thanks guys for the input!

I agree with gotcoalman, if the pad was worn to metal then the noise would occur everytime I brake, and I would most likely feel a difference in balance between the left and the right side as well. Most of the times the braking is completely normal, did try everything from normal braking down to where the ABS kicks in.

Good to know that sticky caliper slide pins causes scoring either top or bottom of the disc as well, that means it can probably be ruled out.

Seems that this is most likely some very hard debris material of some kind, somehow found its way in there and now is stuck on the pad

Damn it... the timing on this is bad, we've got minus degrees and 10cm of snow outside and I don't have a garage here in the city. Might need to drop it in for a service station to check this for me then if I don't come to think of someone who could lend me their a garage with enough height

If I find a garage to check it myself, the caliper sits with two bolts right, in the same way as in this video? (video is a 2007): https://youtu.be/gwdt1psZXac?t=1m28s

Just loose those two bolts and no need to disconnect any hoses and worry about fluid and air right?

[vanfox]

Couple of points:
That's not a Smiley, would it were that simple!
He forget to mention when retracting the pistons you may well get a drop or ten of brake fluid overflowing the master cylinder all over your engine bay paint.

[eresseraca]

Alright, so had time to do a proper inspection today in daylight. Discs are severely worn at the edges... just didn't see this in the dark. So that means that pads might very well be worn as well, even if gotcoalman pointed out that pads down to metal should score the disc all over.

Look as if need a proper brake overhaul, new pads and discs.

Since it's minus degrees, snow and winter up here this means that I won't start fiddling with this myself, nor can I wait until summer with it. So I guess the only option is to open the wallet and drop it off at a service stations for a new set

Oh, and vanfox. I didn't check the whole vid through so might very well be some glitches in the instructions. Was just looking for a video showing how the calipers are bolted and how to get them off.

Disc05.jpg

Disc04.jpg

[MinorMatt]

Im with the coalman...

Pads don't wear totally evenly and you may be down to the metal at one side and have a small amount on the other.

Symptoms are entirely consistant with worn pads. Some pads even have acoustic indicators in the material that make this noise when replacement is overdue...

[vanfox]

Oh, and vanfox. I didn't check the whole vid through so might very well be some glitches in the instructions. Was just looking for a video showing how the calipers are bolted and how to get them off.

No glitches just completely the wrong video. Your note says 2007......

[eresseraca]

Thanks MinorMatt!

Vanfox, sorry my bad, I misunderstood you. Though you meant there was something wrong with the video writing:

He forget to mention when retracting the pistons you may well get a drop or ten of brake fluid overflowing the master cylinder all over your engine bay paint.

and yup my note says 2007 as I just wanted to point out that I was aware this was on a newer model, but still asking the question whether the Mk5's calipers bolts in the same manner with two bolts on the back holding it in place. But since this afternoons findings means a complete brake overhaul I'm leaving it to the service station anyways

[cherniy_chack]

Replacing the brake pads is a routine operation, but if you have never done this, then trust the experts.
The minimum thickness of a solid brake disc is 12.15 mm, vented-24.3 mm