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Help! brakes


Bonfire

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Good afternoon, this is my first post on this forum, I've been watching for a while and was about to mention myself but the Defender 90 has done it for me. :(

Ive had a brake fluid leak that ive now found (front N/S caliper) and being a small leak took some finding, so i checked everything starting at the master cyl. I pulled it back leaving the reservoir in place. Finding no leak, I replaced it and now the brakes are mega sharp (i did think that i didnt have as much servo effect a few months ago so perhaps there was an air leak at the master that ive cured) and however hard i brake I cant get the back wheels to lock (the fronts lock Ok). Do you think its the PRV doing its stuff, or do I need a new landrover. :blink:

Is it possible that tilting the master cyl thats about 1/2 full of fluid has uncovered the piston for the rear brake and allowed air in.

Thanks very much in advance,

James. (bonfire)

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Most likely it is the shuttle valve - might be a PRV? which shuts off the supply to front or rear if there is a pressure loss. It tends to stick and is easily activated by bleeding the brakes.

It looks like a tube bolted to the engine side of drivers footwell with four pipes going in and a pair of spade terminals in the middle (supposed to make brake warning light come on - but I've never known one actually do it.)

If it is at fault, you can dismantle it (in situ if you are tall) and restore the shuttle to the middle position.

Welcome to the forum - by the way!

Si

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Is it an easy job to sort it out, my haynes doesnt say anything about it (buy the proper book they say!). Just a matter of taking something off and moving the thing inside?

Thanks again

It has an end cap screwed on either end - take off and move shuttle. There is also a spring behind each end cap - remove carefully or they will probably fly off to the other side of your garage, never to be found! :)

Failing that, they are fairly cheap to buy. I had endless problems with one until I replaced it (by the side of the road outside Marshals LR in Cambridge - so must be fairly easy).

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Thanks for the advice, I will have a go at resetting it tomorrow, perhaps I got some air in the master when I moved the cylinder about on its pipes, as it didnt have a lot of fluid in it "DOH"....which then set off the shuttle.

At least Im off work this week so theres a blessing :)

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Good afternoon, this is my first post on this forum, I've been watching for a while and was about to mention myself but the Defender 90 has done it for me. :(

Ive had a brake fluid leak that ive now found (front N/S caliper) and being a small leak took some finding, so i checked everything starting at the master cyl. I pulled it back leaving the reservoir in place. Finding no leak, I replaced it and now the brakes are mega sharp (i did think that i didnt have as much servo effect a few months ago so perhaps there was an air leak at the master that ive cured) and however hard i brake I cant get the back wheels to lock (the fronts lock Ok). Do you think its the PRV doing its stuff, or do I need a new landrover. :blink:

Is it possible that tilting the master cyl thats about 1/2 full of fluid has uncovered the piston for the rear brake and allowed air in.

Thanks very much in advance,

James. (bonfire)

No learned message, apart from welcome to the forum, nice to see another Defender owner. Let us know how you get on. Loads of people read the posts and then someone usually comes up with a cracking answer.

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Well i went to bleed the back brakes, just to see what happens, and fluid comes out, by the eezibleed and by 2 man bleeding methods, surely if fluid is coming out the shuttle hasnt moved, or does it only come into play with the higher pressures of actual brake operation?

The back brakes do work a little as they get warm after some left foot braking but not as hot as you would expect. I havent taken the shuttle to bits as it isnt too convinient at the moment, so i think i will just buy another one, seeing as ive got to repair the front caliper anyway. See what happens from there.

Is there any way I could have put the master on the servo incorrectly, there is a tin washer in there on the little pushrod which doesnt seem to go anywhere? :o

James

Ta again.

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Well i went to bleed the back brakes, just to see what happens, and fluid comes out, by the eezibleed and by 2 man bleeding methods, surely if fluid is coming out the shuttle hasnt moved, or does it only come into play with the higher pressures of actual brake operation?

The back brakes do work a little as they get warm after some left foot braking but not as hot as you would expect. I havent taken the shuttle to bits as it isnt too convinient at the moment, so i think i will just buy another one, seeing as ive got to repair the front caliper anyway. See what happens from there.

Is there any way I could have put the master on the servo incorrectly, there is a tin washer in there on the little pushrod which doesnt seem to go anywhere? :o

James

Ta again.

So long as the pipes go to the same places on the master cylinder - there is nothing else you could have done wrong.

I would not rule out the shuttle valve because you get fluid coming out while bleeding - a little leaks past under low pressure.

Try pressing hard on the pedal and getting an assistant to loosen a bleed nipple on the rear. It's hard to judge, but see if you get a similar amount of pressure and volume on the front v the rear. You can usually tell by the rate the pedal drops.

It may not be stuck with one port completly closed, just partially, which reduces the flow and in turn the impulse pressure when you stomp on the pedal.

Si

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