Brake Bleeding

[FurioKid]

Hoping someone can help, i've serviced all my brake calipers and replaced all brake pipes and hoses and the master cylinder during an overhaul. Rebled the braking system and got fluid coming out of all the bleed nipples but the pedal still goes to the floor, but is solid if you pump it.

However discovered that if i pull the rear load sensing valve so ias its open more the pedal is more solid and the brakes work better??

Any ideas? does it mean the rear load sensing valve is knackered or theres still air in the system causing the valve to not pressurize fully??

[jay28]

New poster! (less than 10 posts)

Theyre an absolute git to bleed!! Best way is to pressure bleed it. Do you have the car flat on the deck?

[FurioKid]

No gotta have it jacked up so as to get underneath

just can't work it out cos i've got fluid coming out of every nipple with no air but if you press the brake pedal it goes straight to the floor and none of the brakes lock on. if you pump the pedal a couple of times the pedal is better the brakes lock on showing that theres still air

But as i've said if i pull the rear load sensing valve out more the pedal is more solid and the brakes lock on with one press of the pedal

[FurioKid]

Anyone?!

[Chris Hebden]

It takes blooming ages matey! I cabled tied my load valve all the way on and with someone sat in the car i opened the bleed valves up one at a time and got them to keep pumping the pedal (slowly- emphasise) until the majority of air was out and then went to the slow way of bleeding the brakes (open, down, off, blah blah). Worked a treat!

[FurioKid]

Ah right so if i pull the rear valve open and keep it open via cable tie etc then the fluid can run through easier?! or should i push the lever in then cable tie it?!

[Chris Hebden]

From under the car, push the lever upwards/frontwards and then hold it there with a cable tie. You'll notice when the brake pedal is pushed the lever will move down/backwards if its not held with a cable tie

[FurioKid]

Yeah i know what you mean, ok i'll have a go trying that. Thanks for the help mate

[FurioKid]

Well had a go at doing what you suggested and cable tied the load valve so as it doesn't move when the pedal is pressed and tried bleeding the brakes again. I've got fluid coming out of all 4 bleed nipples yet the brake pedal still goes to the floor on the first pump and then goes hard after 2-3 pumps but goes to the floor when left and tried again.

Been getting the pedal pumped up hard then opening the nipples and only fluid is coming out, and gone round every corner and done it a few times but still no better?!

Help please?!?!?!?

[Chris Hebden]

Sounds like you have other issues in that case mate. I would be looking at replacing the master cylinder as the next step, but thats just me

[Tiny Tim]

We had a similar problem with Beardo's Clio. New Master Cylinder sorted the problem. For the sake of what, £30 odd quid, you'll have a nice new trusty master cylinder

[djinuk]

he stated in his first post hes replaced the master cylinder.

[Tiny Tim]

My bad, he did.

Ahhh servo... if that's leaking it wont be giving any pressure.

[Chris Hebden]

I thought if the servo wasnt allowing pressure the pedal would be firm and not soft? Its the only next logical step though?

[FurioKid]

Did think servo but weren't sure to be honest. if it is the servo then if when i pump the pedal up, would it not sink as the pressure discipates?? whereas the pressure stays there until you let off the pedal and leave it for a sec then try it again.
One little thing, the pipe from the servo goes to the inlet manifold doesn't it? Trying anything at the mo but frustrating :-(

also is it worth putting the weight on the rear wheels when bleeding at all? i know theres fluid coming through all the bleed nipples but just feels like theres air there somewhere

[FurioKid]

Anyone?!?!?!?

[FurioKid]

Right i've had another go, this time i've put the rear arms on axle stands so as to put the weight on the compensator. Rebled the rear calipers and still the fluid comes out with no air?! However now the pedal appears firmer and stays firm for longer, takes a couple of mins then try it and it goes to the floor?! Taken the breather pipe off the inlet manifold and pumped the pedal and the servo appears to be working. The breather pipe goes to the outlet on the back of the inlet manifold?

i'm seriously confused, anyone who can help or fancies having a look?

[michael tierney]

make sure your handbrake and rear pads are correctly adjusted first.then i would suggest either pressure bleeding or vacuum bleeding the system.start at the furthest nipple from the pedal then the second furthest ect.

[FurioKid]

yeah i've rechecked my rear calipers and they can't get any tighter on the adjustment. i really am confused by this now. i can pump the pedal up and it stays hard for about a min, then goes to the floor when retried

[Alastair]

It is one of two things mate, either you have a leak some where, or your new master cylinder is fooooked... the pressure must be going somewhere!

[FurioKid]

What about the one way valve on the servo or the one in the inlet manifold?!

[RussellT]

I have had similar issues and I think that maybe if you get air in the master cylinder its a B to get out. I suggest that you try bleeding opposite corners at the same time. You need a pressure bleeder and open opposite corners then have a mate gently press the pedal repeatedly while you look for air coming out. Also tap the lines and calipers to encourage bubles to move out of the system. You will need a big bottle of brake fluid.

Hope that helps

[Pete@Backyard Racing]

brake bleeding sequence

1. left rear
2. right front
3. right rear
4. left front

make sure uve got pleanty ov dot 4 fluid, keep an eye on the res level and keep topping up, get a gunsons ezi bleed from halfords,connect it to a tyre (max 20psi pressure) make sure your brake bias valve is fully open. you may have to bleed the system 2 or 3 times to get it right.
unbolt the 1 way valve on the inlet manifold to servo you should only be able to blow 1 way down it.

[FurioKid]

Cheers lads, i'll look into a pressure bleed kit and try it that way, i'll keep you posted

[tobester]

Sounds like your master cylinder seals are faulty, provided there is no leaking fluid evident around any hose/pipe joins or caliper piston seals i'd confidently say it is a duff master cylinder, particularly as you say you can "pump it up" and when left for a while it sinks to the floor, get it swapped for an alternate unit. It won't be servo.

[FurioKid]

Just another quick thing is that if i start the engine the pedal is worse, like theres no pressure there is difficult to even pump up hard?!