Unable to bleed air from hydraulics.

[2robert4]

I have never had a problem bleeding my brakes as I change the fluid every two years, but after replacing the front flexible hoses I can not get a good pedal. I initially left the pedal hard down for a couple of days to let the air come back up through the master cylinder and this did improve things I then borrowed a vacuum bleeder which draws air through the master cylinder and out the bleed nipple and this improved the pedal a little but that's it. The brake pedal has always been very firm and as I did loose hardly any fluid I can't think why this problem is so bad what does the team think? 

[noddy]

Thoughts ....
As the only thing you have changed are the front hoses - these would be my first suspect.
Are they faulty? were they brand new or old stock - they may have perished and/or 'balloon' when under pressure. This would give a spongier/longer pedal travel.
Just an initial thought - now time to put the thinking cap on ... Bruce is good at working out this kind of thing !

Roger

[canuck]

Thanks Roger

Robert

I need to ask, do you have a brake booster installed? If so I am out of my comfort zone.

 However assuming everything is 'normal' apart from the installation of the new hoses  then ................  jack the car, well supported, road wheels off at all corners.

Some thoughts; and in no particular order ..............

The normal bleeding process is to bleed the line furthest from the master first, then next closest etc.  In your case this would be the LH rear then RH rear then to the front.  

I have found on our little cars that the master cylinder brake fluid reservoir doesn't hold much fluid. What can happen is that  between pumps you could re-are introduce air into the line?

 

The trick is to displace as little air as necessary. So to achieve this it is best to ensure the parking brake is off/loose and not influencing the rear brake shoes.  I find it easiest to crank the brake adjusters 

tight forcing the shoes out to the drum, open/close the bleed nipple if you want. This theoretically compacts the brake cylinder pistons into the cylinder body. Less fluid less air.   I do this at all corners of the car.

Attach a clear hose (must fit tightly) to the bleeder nipple, (sorry vicar) and feed the bitter end into a beaker about half full of brake fluid.  To bleed, you will need an assistant, preferably not the wife (if so keep a family lawyer on retainer). Open the bleed nipple, have the assistant slowly press the brake pedal down and hold down while you close the bleed nipple. Repeat until no air bubbles are seen in the clear line or fluid in the beaker.

Do this at all the wheels for same result until you obtain a 'solid' pedal feel. Loosen the brake adjusters and re set the, hand brake as well. Ensure the brakes are still locking the wheels while attempting to turn them. 

Make sure at the front the flex hose is installed at correct port to wheel cylinder, the bridge pipe is not weeping that sort of thing.

Back to you, I hope this ramble will serve you

Bruce

[2robert4]

Thanks for your comments gentlemen there are no leaks anywhere the Flexi hoses were manufactured in 2010 and are from Club Spares the adjusters on all four wheels are locked there is no servo fitted and the front of the vehicle is jacked up only so as to encourage the air to rise to the highest point. The bleed system I am using draws the fluid out the the bleed nipple using a vacuum without recourse to pumping the pedal so no air can be introduced into the Master Cylinder unless the fluid is allowed to run low which it has not at the moment. I value your feedback as I am at a loss and scratching my head and getting splinters just now.

[canuck]

Robert,

This reads as if you are doing all the correct things, however

 

I need to ask the obvious question.

Are you attempting to bleed out trapped air at the front brake lines only?

There is a line of thinking that implies that if we only 'fiddle' with either end, or one side of the brakes the other will be fine. I have never been happy with this and would suggest to bleed the full system.

You may have introduced air into the rear lines.  Take a look at the junction of the brake lines at the RH flitch panel. (below) Although this junction is installed at a low point in the system, I am of the mind that air can still creep in.

If the case I encourage you to bleed all 4 corners as I described in my previous post. 

Back to you

Salut

Bruce 

[2robert4]

Just thought I would update you gentlemen on the latest regarding the airlock, after leaving the pedal held down for over 24 hours the pedal pressure is now ok as the air has bled itself back through the open port in the master cylinder.
Thanks for your support.
NP

[noddy]

Glad to hear its sorted - nothing like iffy brakes to un-nerve you!

[canuck]

Now isn't that working smart! Bravo, now go driving

B

[trymes]

Gents: I must say that I swear by (not at) my Eezi-bleed from Gunson. It wasn't cheap, and can be a little fiddly, but it makes bleeding the hydraulics a simple one-person operation. I also had complaints about my brakes a few years back, but after adjusting them properly, they are quite good!