Hi,

having some difficulty with the brakes sticking on for the mot. happened before but with a back brake now the front brakes are doing it just as it went for its mot...

recent hoses all round, calipers are nice and free and greased, brake fluid clean, no errors showing up with the module, pistons look fine.

what on earth else can cause this??

When i open the bleed screw there appears to be pressure there and the brakes slacken off, why the pressure be holding on, even overnight?

thanks

How about the brake pedal not fully returning?

pressure on all 4 brakes? or just one or more?
Ifone, could be a faulty hose. ell could be more than one, but unlikely to be 4.
If 4 MC a strong contender.

brake pedal seems fine with a bit of slack at the top of the travel.

Cars done almost 100k so maybe the mc is faulty, original brake fluid was a bit dark and brakes when I bought the car were in a total state (why I got the car very cheap)

The two front brakes seem both very tight, rear left also dragging, a bit less on the rear right, again its pressure being held in the system, slacken the bleed screws and the calipers let go and turn freely.

hadn't considered the mc tbh, was suspecting more the ABS system but couldn't see how that was going to hold pressure.

If it is the master cylinder, loosening the pipes then doing then up again should release the pressure until the pedal is pressed again.

good idea, will do that on the mc, fortunately its very accessible. if it lets go I'll pull it apart and see whats going on

thanks

[Edited on 12/3/17 by Mr Whippy]

Probably not relevant but I had a similar issue with my 07 s40. Brakes would randomly bind on the front right after about 70k. New brake hoses pads and discs. I dismantled and rebuild the caliper a couple of times only for it to happen again within a couple hundred miles.

I eventually changed the single front right caliper and the problem has not reoccured in 20k miles. The guy at the motor factor said that caliper part number was an extremely popular replacement part

Hope you get it sorted

Oh well, took off the master cylinder, can't open it easily due to a circlip design with no lugs or holes but did blow through it and can't see any wrong at all. General condition appears very good. Going to just bleed the whole system again and see if it improves....