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Apr 11, 2014 17:55:50 GMT
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Right, I'm getting frustrated now, a) at my knowledge and b) at the poxy brakes.
My 96 discovery 300tdi, has a brake pedal that has too much travel and does feel a bit soft (I cant compare it to how it should be on a disco as only just got this car which came with the problem). The pedal I would say stops 1.5" from the floor. Pumping the pedal doesn't seem to make much difference. The ABS light is also on.
I was convinced it was the master cylinder, so fitted a new one today, and changed the brake fluid (with a pressure bleeder) until no more air would come out. No difference, arggghhh.
I have checked that the vacuum pump is working. I took the vacuum pipe off the servo and a vacuum is definitely present, the one way valve is indeed working as a one way valve.
The brake pedal doesn't really change whether the vacuum pipe on the servo is connected or disconnected.
With the engine off and the pedal pumped, it doesn't really change, then start the engine and the pedal goes down a little bit more (now an inch off the floor).
All the brake pipes look to be in good condition - but I guess I need to look at them with someone else pushing the pedal.
Anyone enlighten me??
Thanks all.
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Last Edit: Apr 18, 2014 15:38:53 GMT by Deleted
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Apr 11, 2014 18:07:57 GMT
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Flexi hoses can go soft and 'balloon' when pressurised.
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Apr 11, 2014 18:19:03 GMT
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One thing you can try is using a hose clamp (or something like Mole wrench with rubber hose on the jaws to protect) to blank off each flexi hose separately to see if it's one particular calliper. As optimusprime says brake hoses can cause all sorts of problems but on a Disco they are cheap enough to replace if any doubt. Is this vehicle on the road or a project ? If a project have you fitted new pads to old, part worn, discs ? Some vehicles require special techniques to bleed the brakes when ABS fitted and I don't know if that applies to the Disco. I had one ABS equipped car where pressure bleeding didn't work and had to use a vac system instead (but doubt that is the problem in this case)
Paul H
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Apr 11, 2014 18:43:45 GMT
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Cheers guys for the quick responses, I will check all the flexis tomorrow, fingers crossed you are both right. I'm trying to get the car on the road asap, as I need to start using it - I havnt done anything to the brakes apart from new master cylinder and bleeding, will need pads on the back soon, but they are not that bad yet, discs look ok, no bad scoring etc.. Good idea to clamp off 1 caliper at a time.. Any other ideas most welcome
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I recall someone having a git of a time to bleed his brakes. Just could not get an 'air free' bleed. In the end he had to jack the rear end of his truck as high as he could get,and start bleeding at the furthest point away from master cylinder (ie n/s rear caliper)then go to o/s/r then move onto the fronts.
Hope its just a hose issue.
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Apr 12, 2014 10:36:20 GMT
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Are you trying the brakes with the engine running?
Another thing to check is the bulkhead where the peddle bracket bolts, check for corrosion in that area.
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Apr 12, 2014 16:30:10 GMT
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Been bleeding brakes all day and am now almost about to spit my dummy out...............
All hoses are fine and not ballooning.
Bench bled new M/C
Fluid would not flow out of the rear calipers very well, got some air and then fluid but not much, tried it up in the air aswell. Using the pressure bleeder today the fluid wouldn't flow from the bleeder bottle to the m/c reservoir?? I didn't realise and the m/c ran dry briefly, so had to start again obviously. Later resorted to 2 people method.
Only been bleeding with the engine off. ( has got ABS ) have I cocked up by not having engine on for ABS solenoid valves ( I have a feeling I have)
Peddle brackets are not corroded, so no flex to speak of.
Advice greatly appreciated.
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Apr 13, 2014 11:12:56 GMT
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There is a rear brake restrict or valve somewhere.....that will restrict flow to the rear, so could it be something there?
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Apr 13, 2014 12:22:58 GMT
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A trick I've used in the past is undoing the unions along the pipework route (one at a time !) whilst somebody applies pressure to the pedal and then retightening before they lift pedal back up. This works sometimes when there is a stubborn air bubble that can't be shifted by normal means. I also think you should forget pressure bleeding as it's proving not to work in this case so get a mate to help the traditional way. I gave up on pressure bleeding years ago when I discovered vacuum bleeding with a Mityvac is far superior.
Paul H
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Apr 13, 2014 12:37:54 GMT
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Are you bleeding the brakes with the handbrake OFF?
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Apr 13, 2014 13:46:42 GMT
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Are you bleeding the brakes with the handbrake OFF? Hi, the handbrake on the Discovery is a separate drum brake on the back of the gearbox, so no bearing on the process. But I can see where you are coming from. Colin P.S. another way I have heard of is to put brake fluid in an oil can and connect with a hose to the bleed nipple, pump the can and this pushes the air uphill through the master into the reservoir. Because the air will naturally want to rise.
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Last Edit: Apr 13, 2014 13:52:57 GMT by colnerov
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Apr 13, 2014 15:08:07 GMT
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Thanks all very much for replying. I have spent most of the day again bleeding the brakes. I have got fluid at each corner with no air. I have got through an enormous amount fluid, and even had to resort to halfrauds today.
I am thinking that the feel of the pedal on the discovery is now how it should be - but not how I think it should be, I would prefer less travel and for the brakes to start working as soon as the pedal is pressed - I am used to driving a new van everyday so can anyone vouch for the fact the feel of 18 year old brakes are nowhere like new cars? Probably answered my own question.
I think I will get it booked in for MOT, at least that way I will find out if they are working as they should be.
Will have a look at mityvac.
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Last Edit: Apr 13, 2014 15:09:24 GMT by Deleted
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MonzaPhil
Posted a lot
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Posts: 2,452
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Apr 13, 2014 15:47:47 GMT
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The process for one with abs should involve a pressure bleed requiring the abs pump to be run.
The state of the wheelbearings can also have a major effect on pedal feel and travel so jack it up and give them a sturdy wobble.
Discoveries with ABS usually have a fairly solid pedal.
You can also try chocking the pedal down overnight.
It should not really need vacuum bleeding. This would be very unusual. They are prone to sticking caliper pistons too.
Sent from my HTC Desire C using proboards
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Apr 13, 2014 16:46:31 GMT
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The process for one with abs should involve a pressure bleed requiring the abs pump to be run. The state of the wheelbearings can also have a major effect on pedal feel and travel so jack it up and give them a sturdy wobble. Discoveries with ABS usually have a fairly solid pedal. You can also try chocking the pedal down overnight. It should not really need vacuum bleeding. This would be very unusual. They are prone to sticking caliper pistons too. Sent from my HTC Desire C using proboards Thanks Monzaphil, Will having the ignition on run the abs pump? That's how I bled it today. Also used the pressure bleeder today. Will check wheel bearings also. Thanks
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MonzaPhil
Posted a lot
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Posts: 2,452
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Apr 13, 2014 17:16:41 GMT
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I use the diagnostics kit to do full bleeds so probably no use to you. Other option is to pop in to your local independent Landy specialist and ask their opinion.... Unless they have a bad rep and are going to fleece you......
Umm.
Find someone else with a similar car and try their brakes...
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mk2cossie
Club Retro Rides Member
Posts: 2,937
Club RR Member Number: 77
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Apr 13, 2014 20:46:48 GMT
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The usual thing on the Discovery brakes is the pistons siezing in the calipers, and the brake pads themselves sticking in their housings :/ I'd look at freeing off the pads first and seeing what the pedal is like then
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Apr 13, 2014 21:15:10 GMT
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Has it got the right length bit of rod that pushes the piston in the master cylinder - I spent ages with my Schuler range rover working that one out - only had a pedal right at the end of the travel
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Apr 18, 2014 15:37:37 GMT
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SOLVED!!
After all the messing about, it turns out that the brand new master cylinder was faulty - that makes me mad!
Thanks to all who replied.
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Apr 18, 2014 17:47:14 GMT
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It wasn't a Britpart master cylinder was it ?
Paul h
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MonzaPhil
Posted a lot
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Posts: 2,452
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Apr 18, 2014 18:29:18 GMT
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Probably a genuine LR one....
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