Audi A3 Squealing wheel/brakes

Any suggestion for the cause of this seen as my dealer claim they are unable to reproduce?
Audi A3 (2003) - after about 10 minutes of driving one of the wheels starts
to give a metalic squeeling sound intermittantly up to about 30mph. When applying the brakes of any pressure the sound disappears. If (when stationary) I press really hard on the brakes the intermittant squeeling sound seems to disappear for a bit longer. Occurs regardless of weather/temperature.
Not long has its MOT and nothing reported there. Had a service at an Audi dealer who said they were unable to reproduce, but couldn't see any problems with the wheel/brakes and suggested its probably dirt so pressure washed the wheel. Made no difference at all.
No warning lights on the dash to indicate low brake pads etc - car doesn't feel any different to drive and brakes still stop the car as good as ever!
Any suggestions to fix this?
Thanks, Andy
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Could be a bad caliper (or, a caliper gunked up with corrosion and road crap), could be air in the brake line to the offending corner...I suppose even a balky master cylinder might cause something like this.
/daytripper '00 s4 6spd
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daytripper knastet inn: :

My guess, air or [too much] water in the break line. Bleed all caliphers, back wheels first, until brake fluid is clean/new (why not, change all of it). In any case, this is a cheap & fast method before looking into other factors.
Air can also be caused by (once) overheatet brake fluid, sloppy bleeding, or broken/old seals in the calipher - if last, a renewal/overhaul kit would be smart[tm] and rather cheap.
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Might also be the (not anymore) sliding bolts on the back calipher(s),
shown by unsymmetrical worn brake pads. Quite common Audi thing ...
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Try to isolate as to which wheel is making the noise. Once the noise starts pull up on the handbrake gently to see if the noise disappears. If it does than the problem is in the rear wheels. Once you isolate the wheel pull the pads and check to see if they delaminated from the backing plate. Also check the rotors to see if they are glazed. If the appear to be glazed pull the pads and calipers to gain complete access. Next take a roughing pad and scratch up the surface to remove the glaze. Also rough up the pads lubricate the caliper surfaces and reinstall and road test.
wrote:

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possibly the wheel bearing?
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Black_RS4
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