Bleedin' Brakes - Help

[mep12345]

A couple of months ago I changed the calipers and discs on my car for XR4x4 and 260mm with no issues.

Last week I replaced the servo and Master cylinder with a pristine second hand servo and a new MC and bled the system. But the brakes felt slightly spongy after the work. So this week I re-bled and they got worse, in fact I had virtually no braking power when I went for a road test and was glad for living in a cul-de-sac with no traffic.

Took system apart and checked thoroughly - there appears to be nothing wrong, no leaks at brake pedal pressure or easybleed pressure of 15psi (I re-bled with this method for the second time today as I prefer the manual pedal way and easybleed returned braking to the ok but slightly spongy feel of before todays work). The flexibles appear sound although they are old (I know these could be part of the cause but as it was OK before I can't see why they should be).

The only thing I have noticed is that when applying the brake pedal occasionally a tiny bubble appears in the reservoir.

I have put over 4 litres of fluid through the system and it comes out of all four corners clear and bubble free. I really think there is still air in there but can't think of what else to do to get it out.

Is there a specific bleeding procedure for this car? If so what is it as I've bled the brakes at least 3 times before with no ssues until now.

Any help appreciated

Mark

[tozerman]

I had a similar problem when I fitted new bigger brakes calipers to my S3c, what I did was to actually bleed the master cylinder itself by basically cracking open each union in turn and letting some fluid/air out and then rebleeding the whole system again

Also I took the rear drums off and manually adjusted the ratchet adjuster as much as I could before the brakes bound on the drums.

Not too sure which one worked as I did them both together

Another way to try and locate the problem is to one at a time take a pipe of the master cylinder and replace it with a bleed nipple, and if that then makes the pedal firm then that is the circuit that has the problem.

Good luck Mark, I bloody hate bleeding brakes, you have my sympathy.
cheers.....Tony..

[GreenV8S]

mep12345 said:

Is there a specific bleeding procedure for this car?

I don't know about that car, but if the system has been drained down then on refilling you need to chase the air out of every pipe and every component. If you're lucky and the installation has been well designed this just means filling and bleeding the brakes, but in other cases you may need to crack pipe unions open to let air out, or unbolt components and turn them over to chase the air up to an outlet.

The fact you have air bubbles coming back into the reservoir is not an encouraging sign, I have to admit. It may be a clue that there is a duff seal in the master cylinder.

[mep12345]

Thanks Tozerman - I've tried your "rear brake adjuster thingy" as I remembered this from the last thread on the subject, I haven't tried the crack the master cylinder unions though may do this tomorrow as I'm sure the air is in that area, could be the slope of the master cylinder that does it and pressure bleeding certainly improved things.

GreenV8S I think the system design in way of pipes etc is pretty reasonable as I've bled these through from dry before without any issues (body off winter before last), although I could take front calipers off tomorrow and see if the air is catching in the iverted U shaped flexibles.

Hopefully another easybleed and caliper "shake" and union "crack" will work

Cheers all

Mark

[mep12345]

cracked the master cylinder unions and the bleed nipple on the spare union again and got a bit of air out - straightened the flexibles and "shook" the calipers no air from here.

Pedal feel is now better, but not perfect, although this could just be me imagining the problem now, certainly it is good enough to drive without any issues

I think the angle of the MC on the car causes air to collect at highpoint which is by the front brake unions and as I fitted a dry brand new MC it wouldn't clear without cracking the unions and it was this tha was giving me the smaa bubbles in the reservoir as these have stopped now. Oh well you live and learn.

Thanks for help as usual

Mark

[tozerman]

Glad you got it sorted Mark, Now get those wheels back on and go for a blast, I'm sat at work at the moment but you have no excusse.
Cheers.....Tony..

[Barkychoc]

Are you just opening the bleed nipples a little bit?
I found that opening mine quite a lot and getting a really good flow rate helped to get the air out.

[clarenceboddiger]

GreenV8S said:

mep12345 said:

Is there a specific bleeding procedure for this car?

The fact you have air bubbles coming back into the reservoir is not an encouraging sign, I have to admit. It may be a clue that there is a duff seal in the master cylinder.

Although I have had to crack unions on a car (VW)

Edited by clarenceboddiger on Sunday 31st May 13:19

[pies]

Pump the brakes till they are solid,then wedge the brake pedal down overnight.I've not idea why this sometimes works but it does

[mep12345]

Chris, started cracking them then opened wide to get good flow. Will try Colin's (aka Pies) suggestion, but at moment am thinking of running for a few weeks then having another bleed when system has settled down.

Tozerman - work or no work got the inlaws here so disapperaing isn't an option, am in doghouse enough for working on the drive, but am taking her back to Swindon with me tomorrow so will get a good couple of hundred miles then and the weather is just as good but setting out at 6am he sun won't be quite so bad on my Ginger (and bald) head

Mark

[phillpot]

had similar problems recently,got an improvement by cracking open connections to balance valve while system pressurized with "Easibleed" then re-bleeding rears, a huge bubble came out !
Anyone tried running without that balance valve ? under serious braking my S3 will lock fronts but not rears, perhaps it works too well ?

[Loubaruch]

Have never liked Easibleed, too much messing around with tyres etc. Prefer to suck the fluid out of each bleed nipple rather than pressurise it from the master cylinder. I use a fluid drainer illustrated here:

http://bertram-hill.co.uk/toolsandtips.aspx

Have never experienced any problems bleeding any car even Series Landrovers that are notoriously difficult. Costs a few more pounds than Easibleed but you can also use it to drain gearbox/axle oils. Have even used it to drain coolant to save the flooded garage floor.

[Oldred_V8S]

Loubaruch said:

Have never liked Easibleed, too much messing around with tyres etc. Prefer to suck the fluid out of each bleed nipple rather than pressurise it from the master cylinder. I use a fluid drainer illustrated here:

http://bertram-hill.co.uk/toolsandtips.aspx

Have never experienced any problems bleeding any car even Series Landrovers that are notoriously difficult. Costs a few more pounds than Easibleed but you can also use it to drain gearbox/axle oils. Have even used it to drain coolant to save the flooded garage floor.

Paul.

Where did you get hold of this?

Cheers,
Paul

[Oldred_V8S]

Loubaruch said:

Have never liked Easibleed, too much messing around with tyres etc. Prefer to suck the fluid out of each bleed nipple rather than pressurise it from the master cylinder. I use a fluid drainer illustrated here:

http://bertram-hill.co.uk/toolsandtips.aspx

Have never experienced any problems bleeding any car even Series Landrovers that are notoriously difficult. Costs a few more pounds than Easibleed but you can also use it to drain gearbox/axle oils. Have even used it to drain coolant to save the flooded garage floor.

Paul.

Where did you get hold of this?

Cheers,
Paul

[Gerald-TVR]

here
or
here

Edited by Gerald-TVR on Thursday 11th June 07:43

[Oldred_V8S]

Gerald-TVR said:

here
or
here

Edited by Gerald-TVR on Thursday 11th June 07:43

That's great thanks, wonder what the difference is between the two, beside the price, will give them a ring.

[Oldred_V8S]

Gerald-TVR said:

here
or
here

Edited by Gerald-TVR on Thursday 11th June 07:43

That's great thanks, wonder what the difference is between the two, beside the price, will give them a ring.

[Barkychoc]

One is plastic, the other is metal.