Front brakes binding

[mattfx81]

I've read a few threads on here regarding this. Since my front brakes started binding on my 2001 1.4 berlingo, i've fitted new discs, pads, calipers, flexi hoses, new fluid and the caliper carriers have been cleaned of all corrosion, it bleeds up ok aswell and the pedal feels normal. Still doing it though, Ive read about a servo relief valve possibly causing this? Could a fault on the ABS system also cause this problem?
Im pulling my hair out now and cant really afford to throw any more money at fitting new parts, im self employed with a new baby at home.
Any help appreciated.

Matt

[brodfather11]

Sticking brakes can be caused by the brake caliper piston sticking, caliper sliding pins sticking/bent , which mine had, or faulty master cylinder not letting the fluid back to the reservoir. There is a check valve on the servo unit which lets air flow in only one direction, not sure about a servo relief valve though. Since you've changed the calipers the piston can be ruled out and if the calipers are sliding ok I would opt to check the master cylinder.
Are they binding all the time or just now and again?.
The ABS unit gets a lot of blame for things going wrong when its not at fault.

[mattfx81]

Cheers for the reply.
That check valve on the servo must be what ive read about is that an interchangeable part or does it require a whole new servo unit?
Im there a check or any procedure I can do on the master cylinder to check its function?

[brodfather11]

I think the check valve can be obtained separately. If you have a diesel engine the vacuum is provided by the vacuum pump on the engine , a petrol engine provides a vacuum via the intake manifold which if not working properly would make your brakes feel hard to operate.
Are your brakes are sticking on all the time or just occasionally? When they are sticking on, jack it up and see if the front wheels are free, if not open a bleeder to see if there is any pressure in the brake lines, remembering that they have a split system, one half of the master cylinder works one front wheel and the diagonally opposite rear wheel. If after opening the bleeder and the fluid spurts out and the wheels turn easy then I would change the master cylinder
Another problem comes to mind is that the brake light switch is not allowing the brake pedal to return properly thus keeping the pedal slightly under pressure

If your problem was only on the back wheels then the load limiting valve mounted on the rear sub frame would be a suspect.

[mattfx81]

It was intermittant but is constant binding now, when its bled up they spin freely. Ive not noticed the back brakes binding or they dont feel like they are. I will have a look at that brake light switch. Is it possible to adjust the pedal aswell?

[ron]

If you have free play on pedal,I would suspect the mastercylinder.

[mattfx81]

How do you define free play, do you mean pedal going all the way down or inconsistant pedal? If I pump it a few times it goes solid and stays solid with the ignition off

[brodfather11]

The fact that the wheels spin freely when you bleed them points again to the master cylinder

If you press your brake pedal with your fingers and it should have some movement before it gets hard, that's free play. I doubt if you can adjust the pedal, if there's no free play then the master cylinder rod is pushing against the back of the brake pedal or something is stopping the pedal coming right back (pedal return spring broken?) and releasing the pressure in the master cylinder/brake pipes. The seals/valves in the master cylinder can distort and stop fluid returning to the brake fluid reservoir.

You said "If I pump it a few times it goes solid and stays solid with the ignition off "

When the pedal is hard then keeping your foot on the pedal to keep it solid, start it up and the pressure should ease, you'll feel it through your foot , That's the servo working.

[mattfx81]

A second master cylinder solved the problem first one was faulty. Got a new problem now though engine is knackered, bottom end is going...

[ron]

A second master cylinder solved the problem first one was faulty. Got a new problem now though engine is knackered, bottom end is going...

Don't drive it.Whip off the sump & rod caps.Check crank journals for ovality & scoring.If caught quickly enough you won't need to grind the crank.Iff crank is good,fit a new oil pump as well as shells.If not too difficult,change the main bearing shells as well.Good luck.:thumbsup::thumbsup: