Disco 2 Brake bleeding woes

2003 Disco 2 ES manual. No ACE.

The initially firm brake pedal started gently sinking at traffic lights to recover on release and slowly drop again. I assumed master cyl seals and fitted a new Britpart cylinder.

I’m finding it impossible to bleed, even after 12 litres of Dot 4. I’ve gone round it countless times with a power bleeder @ 15psi, 10 psi & 5 psi and 4 times with Hawkie rattling the valves . I’ve tried bleeding it with the pedal jammed down and also with the engine running. I’ve also tried backing off the pipes on the modulator, which produced fluid. I’ve bled it multiple times with the pedal.

Overall the amount of bubbles which have come out would fill a barrage balloon! Although very little air comes out now, the pedal still goes straight to the floor. There are no leaks of fluid.

Brake pads have done about 200 miles, so there can’t be much space behind the calliper pistons.

I really need to use it on Saturday as 2 Labs and 2 people don’t fit in an MX5, so would hugely appreciate some advice please?

Many thanks!

Are you SURE there is nothing wrong with the new master cylinder?
sounds like it is somehow sucking air in or summat.
Valve.rubbers fitted the wrong way round?
all connections really tight and not leaking air into the system?

I'm beginning to suspect the new cylinder, but certainly didn't dismantle it before fitting. I've ordered an OEM seal kit for my LR original, so will try that if no other ideas.
Unaware of any leaks - It is on stands on a concrete garage floor. Only three pipe connections were undone and they are all tight. However am aware that I've obviously missed something for there to be a problem! Thanks for getting back

Tim C said:

I'm beginning to suspect the new cylinder, but certainly didn't dismantle it before fitting. I've ordered an OEM seal kit for my LR original, so will try that if no other ideas.
Unaware of any leaks - It is on stands on a concrete garage floor. Only three pipe connections were undone and they are all tight. However am aware that I've obviously missed something for there to be a problem! Thanks for getting back

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I'm in Ferndown when at home but will be in France until the end of September otherwise I'd come and have a look with you.
There are other threads on this both on here and in the general Landy forums. Have a good search. But am there with you on the "replace the seals" front, provided the old one isn't scored or anything.
Best of luck!

We're just South of Shaftesbury and it is a wedding near Ferndown that we are trying to get to! If you are in France, hope your aircon is up to scratch!
I have trawled quite a few forums which are hugely helpful. It is just that I haven't found another poor sod with quite the same problems!
I;m no mechanic, but at 69, I've done a lot of brakes and this is a new one on me!
Thanks again.

As well as a dodgy seal in the master cylinder, which sounds most likely as air in the system makes it spongy, not slowly drop, in theory could be a dodgy seal in the abs unit, though they are generally quite reliable.

Turn the engine off and pump the pedal until it loses all vacuum and goes hard, then press and hold the pedal, does it still drop? You'll need some weight on it as there's no assistance

Tim C said:

We're just South of Shaftesbury and it is a wedding near Ferndown that we are trying to get to! If you are in France, hope your aircon is up to scratch!
I have trawled quite a few forums which are hugely helpful. It is just that I haven't found another poor sod with quite the same problems!
I;m no mechanic, but at 69, I've done a lot of brakes and this is a new one on me!
Thanks again.

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Aircon functionning although leaky. I top it up every year,
We use our other car mostly which is a Citroen Pluriel, with all sorts of configurations of top back, top off, windows down etc etc but no aircon. We live by the sun and not by the clock! at 600 metres up it is a touch cooler.
You're 2 years older than me so you'll remember 1976 etc. And like you I have done loads of brakes including the notoriously hard to bleed, old style Mini.
Do hope you get to the bottom of it.

Do you get a normal hard short pedal if you apply the brake pedal hard and fast ?
If yes and the pedal is soft and long when applying slowly, it sounds like your new mastercylinder is either faulty or now has dirt / debris sitting on 1 of the high pressure seals.
Did you fit a new fluid reservoir or re-use the old one ?
If using the old one, could there have been dirt in it which has been moved into the mastercylinder ?

There are 6 flexi pipes on you braking system, one on each wheel and 2 more under front wheel arch, they jump the body onto the chassis, if you clamp off the all the flexi pipes that should give you a solid pedal, if you don’t then the problem is with the master cylinder, OK so far

so let’s assume, your pedal is solid, so looking at your ABS, the 3 pipe on the top from the front, should go to the rear drivers side wheel, so remove the clamp at this point under the front wheel arch ,check the pedal is solid, if it is, remove the rear drivers side clamp and check the pedal, and bleed the brake, now it should be solid as you only have 1 line open the other 3 are still clamp up, if it not solid then that’s the problem wheel, if it solid, you now know that that line is good, replace the clamp under the wheel arch, repeat the action for the other 3 wheel to try and identify the problem area, , so it should be the other rear next, the then the driver’s side front, the near side front, remember it furtherst to nearest

frostythor said:

There are 6 flexi pipes on you braking system, one on each wheel and 2 more under front wheel arch, they jump the body onto the chassis, if you clamp off the all the flexi pipes that should give you a solid pedal, if you don’t then the problem is with the master cylinder, OK so far

so let’s assume, your pedal is solid, so looking at your ABS, the 3 pipe on the top from the front, should go to the rear drivers side wheel, so remove the clamp at this point under the front wheel arch ,check the pedal is solid, if it is, remove the rear drivers side clamp and check the pedal, and bleed the brake, now it should be solid as you only have 1 line open the other 3 are still clamp up, if it not solid then that’s the problem wheel, if it solid, you now know that that line is good, replace the clamp under the wheel arch, repeat the action for the other 3 wheel to try and identify the problem area, , so it should be the other rear next, the then the driver’s side front, the near side front, remember it furtherst to nearest

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Wow, I must print this off, it is so concise etc.
Ta mate!!

the only other thing i would add is if you dont have brakepipe clamps , and a are using Mole type grips, the cut a 20mm piece of garden hose and put it around the flexi pipe to help protect the flexi from damage,from a sharp edge, you dont want to get it all done and sorted to find you have damaged a flexi and it now needs replacing

It's important to know that as long as the ABS modulator is on the circuit the pedal will not go rock solid with ignition off whatsoever cos there are expansion chambers in it, the pedal gets hard untill about 3/4 of travel then if you keep pressing it will go slowly down to the floor while the air is compressed in the chambers and that's normal... the only way to get a rock solid pedal on a D2 is to block the outlets from the master cylinder. If there are no leaks and the system was power bled with diagnostic tool then pedal bled IN THE CORRECT ORDER as in the book but is still not OK the master cylinder is the first suspect... being sh*tpart it won't be a big surprise

Firstly, thank you all very much for your replies & advice. The Britpart cylinder came with reservoir and all the now 15 litres of fluid were new! (Not the best spend of £79! The question is whether I have the nerve to poor it all around the trunk of a hideous tree, which my wife insists on keeping!) Even my Sealey power bleeder was new.
I have tried all your suggestions, but still no resistance on the pedal. I followed the Hawkeye bleed order each time and the order listed in Rave for normal bleeding.
frostythor, a special thanks - I will print & keep that. I clamped off all the flexi hoses as you suggested and sill the pedal goes to the floor and so the fault must be with the m/cyl.
A local L/R specialist thinks he can get me a new (formerly) Lockheed cyl tomorrow at roughly the same price as the Britpart, so will fit that.
I know that Britpart now seem to earn a bad press, but I ran a Disco 300 for 14 years using mostly Britpart (including hydraulics) without problem. However I appreciate that they are merchants & not manufacturers. When you have a thatched roof and a pension, sometimes the cheaper option looks attractive, if not a wise one!
Will keep you posted when the new cylinder is fitted.

Tim

Hi Sierrafery, having gone through the manual I see that, my disciption is opposite the landrover one, so it need to change from farthest to nearest first the so front left, front right, the rear left, finaly rear right

The Britpart cylinder will be collected by the binmen tomorrow! The OEM master cylinder I ordered was for the wrong car. The OEM seal kit I ordered for next day is on back order.
Genuine LR cylinders seem to have vaporised and all the suppliers I've tried are out of stock. The only one I can find is a whopping £360 and I have as yet to confirm availability.
In desperation, I have refitted the original LR one to see if by chance clean fluid might fix it.
It is bleeding out as it should but still has a very small amount of air coming out for me to clear tomorrow when hopefully it will be a tad cooler!
Curiously now I have a fairly firm pedal with engine off, but goes softer and my foot slowly dips to the floor when the engine runs. Could that be caused by a vacuum leak?
(It has done 112,000 miles )

Tim C said:

Curiously now I have a fairly firm pedal with engine off, but goes softer and my foot slowly dips to the floor when the engine runs. Could that be caused by a vacuum leak?

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That's normal as i already explained, as long as it is breaking well dont stress yourself, a vacuum leak would make the pedal harder not softer... for the cylinder search TRW PMN221

Have you tried any of the Salvage Breakers websites for a good used one

Tim C said:

The Britpart cylinder will be collected by the binmen tomorrow! The OEM master cylinder I ordered was fo
r the wrong car. The OEM seal kit I ordered for next day is on back order.
Genuine LR cylinders seem to have vaporised and all the suppliers I've tried are out of stock. The only one I can find is a whopping £360 and I have as yet to confirm availability.
In desperation, I have refitted the original LR one to see if by chance clean fluid might fix it.
It is bleeding out as it should but still has a very small amount of air coming out for me to clear tomorrow when hopefully it will be a tad cooler!
Curiously now I have a fairly firm pedal with engine off, but goes softer and my foot slowly dips to the floor when the engine runs. Could that be caused by a vacuum leak?
(It has done 112,000 miles )

Click to expand...

That pedal should be firm when engine off and dip when you first start engine as Sierraferry has already mentioned...

Again thanks for your helpl
The original cylinder is on the car and bled out, but behaving the same as when I removed it. I've driven this Disco 22K, so am used to "the dip" on starting!
This is certainly not a normal pedal, I wouldn't even drive it like this on the flat, let alone down the A350 from Shaftesbury with a couple of tons of aggregate behind - which I do a lot! ( If you have seen the old Hovis, bread on a bike advert, you'll understand!)
Genuine LR cylinders for my late chassis number, are out of stock everywhere as are LR seal kits. LR won't even give a date.
So my options are very reluctantly - used - not found one so far.
Another Britpart treasure, hopefully from another batch - very wary!
A Britpart seal kit in my LR original - even more wary!
So between a rock & a hard place.

I'm amazed LR even do seal kits for mastercylinder internals. I used to work for the mastercylinder manufacturer Lucas Girling & for many years LR would never accept the safety issues relating mastercylinder seals being changed by owners / mechanics.
I'd go for good second hand unit from a reputable breaker.
Paul McGill (Discovery 2 Parts) is always reliable.
He's also known as Heathy on the D2BoysClub forum & also operates on Facebook as Discovery 2 Parts.
I think his mobile is 07828278465