Damn Brakes!!

[hotdeffender]

 

The brakes on my car just will not bleed. If you keep pumping, then you get a reasonable bit of brake pressure, but as soon as you let it go for a few seconds, its back on the floor next time you press it!

It has had new wheel cylinders (no leaks)

Its on its second new master cylinder (no leaks)

I have even replaced the rubber pipes from the resovoir to the master cylinder.

you can see that the plastic union for the front brake circuit inlet on the master cylinder is bubbling away when you pump the pedal.

We have used the pressurzed easy blled kit. the simple non return bleed pipe and the traditional 2 man method and litres of brake fluid. it just wont have it.

There are no bubbles coming out at the wheels, so weather they are just supplying nasty cheap master cylinders i dont know.

Any ideas?

[Rusty's Uncle]

Not sure about the bubbles inside the plastic union which does not sound right but one of the major problems can be down to the brake shoes springing back on the self adjustors. Bleeding with the hand brake full on might help. You can also isolate individual wheels by using brake pipe clamps on the flexible hose to track down problems, good luck 

[ChrisRLewis]

Perhaps the master cylinder required a bench bleed before it was installed?

[Pete126]

I have in the past had someone press the brake pedal down slowly while I loosened the pipes on top of the master cylinder until it started pumping fluid through, then nip it up and go through the brake bleeding sequence again  

[damon500]

The best solution I have found to bleeding brakes is simply to gravity bleed them, just fill the reservoir and undo the nipples one at a time starting from the furthest point from the master cylinder. Normally if you leave them open for about 15-30 mins each and keep the reservoir topped up it works a treat.
Also remember that even if you bleed the brakes fully you won't actually get proper pedal travel until you have (self) adjusted the brake shoes- once you manage to get the pedal to go solid at the bottom of its travel then (carefully!) drive backwards and forwards a few times and hit the pedal sharply- this will provide the initial adjustment of the shoes.
Once you have done this a few times you should have half pedal travel- when you drive the car the pedal travel will then start to further reduce as you brake more often and the shoes bed in and adjust out to full travel.
Hope this helps! 

[hotdeffender]

Cheers guys, ill give it a go, I think ill try a new master cylinder as w

ell.

[ChrisRLewis]

If you do remove the master cylinder or replace, don't forget to bench bleed it does save a lot of problems.

[youtube]http://www.youtube.com/watch?v=vOuDEiwiozQ[/youtube]

[GTMaster]

Also something i noticed when i had fixed the brakes:  brake pedal travel can also be adjusted/affected by the brake light switch. When i adjusted mine the brake pedal didn't come up as high and there was a  smaller amount of play before the brakes functioned...