Hard brake pedal on 2a

[the big fist]

Hi all,
I have a problem with my 2a 109 which does not want to go away.
The brake pedal becomes rock hard after a few pumps and I have to leave it like this until it resets itself. I had it happen once before and it was the pushrod length adjustment on the master cylinder. I have fiddled with this to no avail, but in a very non technical way.

I have new shoes, cylinders and brake lines but not new flexible lines. I also thought I may have had the springs on the wrong side of the shoes but am fairly confident I have put them on correct. (LR has been off the road for about 2-3 years). It would be great to get this up and running again as I sorely miss driving it.

Cheers,

Peter

[hesguitar]

Blockage? if it's been sitting for a while the lines may have rusted internally. Brake fluid can attract an alarming amount of moisture just from the air.

[JDNSW]

I would guess a master cylinder fault, probably from sitting for a long time. It won't be the hoses, I wouldn't think. When the pedal goes hard, are the brakes locked on? If not, the problem is probably the pedal pivot binding, or possibly the piston in the master cylinder sticking.

John

[isuzurover]

I would guess a master cylinder fault, probably from sitting for a long time. It won't be the hoses, I wouldn't think. When the pedal goes hard, are the brakes locked on? If not, the problem is probably the pedal pivot binding, or possibly the piston in the master cylinder sticking.

John

x2. Pull the MC apart and inspect. If the bore and piston are OK you can just put a seal kit through it.

[the big fist]

It's actually part of the reason it is parked up. Did it early on, not only recently.
Will check to see if the brakes are locked on or not.

I can see the pushrod going in and out of the master and it feels like the piston is coming back with the pedal. The lines would be full of air as I have just put a new solid one on from junction to front left wheel. So lots of air. Yet if I pump the pedal it slowly builds pressure and then goes hard. So in other words the pressure isn't being released when the pedal retracts.

[JDNSW]

It's actually part of the reason it is parked up. Did it early on, not only recently.
Will check to see if the brakes are locked on or not.

I can see the pushrod going in and out of the master and it feels like the piston is coming back with the pedal. The lines would be full of air as I have just put a new solid one on from junction to front left wheel. So lots of air. Yet if I pump the pedal it slowly builds pressure and then goes hard. So in other words the pressure isn't being released when the pedal retracts.

This indicates the piston is not coming back far enough or the passage that allows fluid back into the reservoir when the pedal is released is blocked. Possibly the piston is sticking due to rust in the bore as it gets to the end of its stroke and the spring pressure is less, or due to the seals being swollen by contamination with oil (even dirty hands will do it!).

Master cylinder out, strip and examine, I am afraid, unless the piston rod is incorrectly adjusted.

John

[the big fist]

Hi John,
do you have any information on how to adjust the piston rod ?
This cured it before but I cant find any information on it.

I was planning on doing a little testing tonight by cracking brake lines in certain spots to see where the pressure build up is.

Cheers,

Peter

[the big fist]

OK, did a little bit of diagnosing tonight.
I got the pedal hard then cracked the line coming out of the master cylinder.
Fluid came out and pedal went soft. When pumping the pedal more fluid came out and I could hear it hissing on the pedal up stroke. My assumption is that the MC is ok as it is trying to suck the fluid back.

So, got the pedal hard again and went to the bottom slave on the front wheel and cracked the bleed nipple. Fluid came out...a little bit. Pedal still hard. Tried to pump, but still hard and no more fluid from bleed.

So I work backwards to the top of the flexible line and crack that where the tube joins. Lots of fluid under pressure. Pedal soft again. Pump the pedal and out squirts lots of fluid.

So I am assuming that its the flexbile lines that are dodgey. I have all new slaves and shoes and springs. Even if the springs were on wrong I would think that the pedal would go hard, maybe just hard to push. I also noticed the flexible line looked oily like the fluid was coming out through it.

Whats other peoples thoughts on this. Would it be likely all the flexibles are dodgey ?

cheers,

Peter

[chazza]

Yes, it sounds as if the hoses have collapsed internally - replace all three and any other dodgy looking pipes whilst you are at it,

Cheers Charlie

[JDNSW]

Does sound as if the problem is the flexible hoses, although this is unusual in my experience. It is likely to be due to fluid contamination with opil (possibly quite some time ago) and I would be very careful to pump plenty of fluid through the system - although you will do this anyway when fitting new hoses.

Piston rod adjustment - I don't have my manuals with me, but all that is required is to remove the small cover plate on top of the pedal box, and adjust the nuts each side of the trunnion in the pedal lever so that there is definitely a bit of pedal movement before the piston rod hits the piston and starts moving it. From memory, there should be around 1cm free movement at bottom of the pedal, but the exact amount is not critical, as long as there is some free play. Note that if the pedal return spring is missing or the wrong spring, the weight of the pedal may stop it from returning in some conditions even if there is free play.

John

[the big fist]

Thanks guys,
Will get a new set today and try fitting over the weekend.
There's been a lot of new fluid pumped through the system due to various lines and cylinders being replaced. Theres a couple of hard brake lines to finish off still. Being stored at a beachside town for many years (before i bought it) means the lines are quite brittle and rusty.
I am going to give the landy a proper stripdown and rebuild once I get a couple of other non land rover projects out of the way !

Thanks again.

Peter

[Johnno1969]

Good luck with it, and I hope that you get it sorted soon. Echoing others, it does rather sound like master cylinder adjustment or blockage.

Funny things, brakes.....

[chazza]

Theres a couple of hard brake lines to finish off still. Being stored at a beachside town for many years (before i bought it) means the lines are quite brittle and rusty.


I suspected as much after looking at your avatar ;)

Don't trust rusty pipes, even if it appears to only to be surface rust. One leak on a single circuit brake system and death-stalks! :eek:

I know what you mean about the difficult ones; on my S3 I re-routed the front two to sit on top of the chassis rails and the LH one runs around behind the engine,

Cheers Charlie