Bleeding 110 brakes NO ABS fitted

[Tim4x4]

Hi I am having problems removing the air from the brake system.

2001 Defender TD5 110 no ABS fitted (large pistons in the front callipers)

Brakes were working fine but checking for the MOT found a couple of rusty pipes and one front calliper weeping slightly. Replaced 2 front callipers, three flexi pipes, 2 steel pipes on the hub assembly and one pipe off side front from the flexi to the rear brake valve.
I used the two man method.
On completion unable to bleed the brakes no peddle pressure at all straight to the floor. I was able to pump fluid through the system OK no issues air visibly being removed from each calliper air bubbles stop, move on to the next calliper (started at rear passenger side then rear drivers side then front passenger and front drivers side) no peddle pressure.
Released the pipes at the master cylinder pump peddle on downward stroke release pipe hold peddle to the floor tighten fitting release peddle same on all three pipes. Then re bleed the whole system still no peddle pressure.
New master cylinder fitted repeated the whole routine of bleeding the master cylinder and the brakes several times and still no peddle pressure.

Tried the pressure bleed method using an easy bleed at 20psi from a spare wheel as directed again bleeding the master cylinder and the brake system still no peddle pressure.

When bleeding the system I have tried it with the vehicle on level ground, raised the rear, raised the front, and raised each side in turn still no peddle pressure.

I have pushed pistons a little way back into the callipers and tried the brakes they all do move.

What am I missing ( I know peddle pressure) but seriously what do I do next or what have I not done correctly?

 

[D90mitch]

Not that I know that much about the brakes but seen as though you've checked everything apart from the servo, I would have a look at that. I believe there was another thread on here similar to this recently who was having a right time getting the brakes to work.

 

[jamesmartin]

have you fluid at the master cylinder fittings when released

 

[Tim4x4]

have you fluid at the master cylinder fittings when released

Yes at all three James.

 

[jamesmartin]

and at each caliper bleed nipple, clear fluid running through a pipe to a container with no air bubbles

 

[Tim4x4]

and at each caliper bleed nipple, clear fluid running through a pipe to a container with no air bubbles

Yes.

 

[jamesmartin]

is there no pressure on pedal or will it pump up

 

[Tim4x4]

is there no pressure on pedal or will it pump up

The peddle will pump up somewhat but not to the extent you would expect. After pumping around 7 or 8 times the peddle will travel about 3/4 of the way to the floor not fully to the floor, release it for a few seconds and the next time it will travel all the way to the floor with no pressure.

 

[jamesmartin]

when pedals pumped does fluid splash up in res , try just pressing pedal twice and hold foot on second is it then firm

 

[Tim4x4]

when pedals pumped does fluid splash up in res , try just pressing pedal twice and hold foot on second is it then firm

If peddle is pumped vigorously then a splash of fluid will come out of the master cylinder top but if using a steady pressure no.

Pressing the peddle twice the peddle will go to the floor but with some resistance just before the end of its stroke. It will take 4 strokes to achieve sufficient pressure to stop the peddle going to the floor.

 

[jamesmartin]

just trying to work out whether serv rod needs adjusting or master cylinder is drawing air in ,presuming the rest of system is good and no loose fittings etc

 

[Tim4x4]

just trying to work out whether serv rod needs adjusting or master cylinder is drawing air in ,presuming the rest of system is good and no loose fittings etc

I have checked all fittings that I have made off and that are sound all tight also made checks at the rest of the system all ok.

As I said the brakes worked fine prior to me messing but I have changed the master cylinder when I was unable to get pressure it is a new master cylinder not used. I just fitted it straight on made no adjustment to serv rod.
What checks should I have made to determine correct adjustment?

 

[jamesmartin]

you can tell by how pedal is , try clamping each flexi in turn , rebleed if theres more air it must be getting in and it takes a few pumps to get air from master to caliper

 

[Tim4x4]

you can tell by how pedal is , try clamping each flexi in turn , rebleed if theres more air it must be getting in and it takes a few pumps to get air from master to caliper

James I will go through the process again tomorrow but unable to clamp off the flex's as they are S/S braided.

I have always preferred the two man method of bleeding and locking o0ff the nipple prior to the peddle returning should I use the pressure method or the two man in your opinion which works best.

I have also seen people use the two man and pressure combined, whilst under pressure bleed as two man, is that worth a try?

 

[jamesmartin]

such is the problem with braided hoses and why im not keen, as it can narrow down an issue,its worth bleeding using the 2 man method closing nipple before pedals let up each time with the plastic pipe so you can see what air is doing ie staying the same or bubbles getting smaller or clearing etc it helps build a story of whats happening, if a system doesnt bleed up by a simple 2 man operation then theres an issue

 

[blue beasty]

I usually use the 2 man or sometimes child method as well though I have pressure option.

Either is preferable to the 1 man 1 woman option......

Ok press down slowly and gently...

is it down?

What? I was on my phone

No worries....ready?

Yes

Is it down?

Yes

Really? All the way?

Yes

To the floor?

It doesn't go to the floor it goes about half way

Ah......that's what I'm trying to sort. Can you press it all the way to the floor please?

If you're sure?

Yes please.....Woooooah!!! that's certainly down

Well you did say

Yes I did didn't I, don't worry I needed a shower anyway....

Whoops my foot slipped off.....

 

[Tim4x4]

such is the problem with braided hoses and why im not keen, as it can narrow down an issue,its worth bleeding using the 2 man method closing nipple before pedals let up each time with the plastic pipe so you can see what air is doing ie staying the same or bubbles getting smaller or clearing etc it helps build a story of whats happening, if a system doesnt bleed up by a simple 2 man operation then theres an issue

Thank you James
Success I now have brakes.

Looking again at the problem and with a statement by James in mind "Air MUST be getting in somewhere" I dismissed it must be a actuator fault in favour of a pipe issue although I could see no fluid leaking.
Fluid leaking was not what I was after it was air getting in, difficult to separate the two because if there is a gap for air to enter then there must be a gap for fluid to leak out.

Removing each new pipe in turn and inspecting properly for any signs of damage. I found near side front steel pipe from flexi to calliper at the flexi joint the swaging was cracked in two places. I replaced this pipe with new and continued to inspect all the rest of the new pipes I fitted no other issues on any of the other pipes.
Bled the brakes using the two man method success brakes now as they should be.

OK so I had a problem with a swaging on the end of a new pipe which was a physical thing but the main problem was me dismissing the thought that the new pipes could be the problem after all I could see no leaks so no problems at any of the new joints.

Why was it not leaking fluid under pressure? I can only think that the way the crack was it flexed under pressure and sealed but without pressure it allowed air to enter. It was at a high point in the pipe so the air bubble collected at the joint no fluid at the joint to leak out, but who knows.