[skyman]

Did you bleed the lines you capped off? If there is air in the back brake lines it will compress rater than work the front brakes.

Did your brake systems work cross wise like ours? The front outlet makes the right front, and left rear brake work. The rear makes the left front and right rear work.

They do it this way so if one system fails you still have brakes on both sides of the rig front and back.

Brent at trail Tough has been known to take the shop forklift and raise the rear of the Sierra way up in the air to bleed brakes. He's got a good shop so I am sure he has vacuum bleeders, pressure bleeders, and power bleeders lol, he says some Sierra's are just bad that way.

When I swapped on the front 4 door kick bakes I bled them out twice one day after another. I took it out and still had to double pump the brakes to get them to work good.

After I took it up on weekend camp/wheel the brakes sucked all weekend so I decided to bleed them again when I got home. By the time I drove home they were working great, and have ever since...go figure..guess the air just worked it's way out.

Anyways I would try jacking up the rear of the vehicle, or parking it nose down on a steep driveway and try to bleed them there. Thats what a lot of guys do here after messing with the brakes. even with the rear brakes blocked. Bleed the lines in the rear you have blocked too.

What is weird is that some guys have troubles all the time, and some never have a problem, no matter what they do. Seems like once you crack the stock system it;s a 50/50 shot.

I hope that helps, hey.

--Sky

[RUN.10W]

Yea mate thanks heaps for your advice, yea I have a step driveway so tomorrow morning I will roll it down the driveway and try and flush it that way, it prob help thanks again

[billrogers]

Hey, please keep us up to date.. you have created a rather interesting topic... My bet is on a ruptured booster diaphram !!
Regards Bill

[skyman]

X2 I would like to know what the problem is when you get it all figured out

[RUN.10W]

Will do guys been flat out last two days so tomorrow arvo I will have another play with it, have got new calipers to try now...

[steak_knife]

RUN.10W wrote:

Yea mate thanks heaps for your advice, yea I have a step driveway so tomorrow morning I will roll it down the driveway and try and flush it that way, it prob help thanks again

You are bleeding on flat ground????

[RUN.10W]

Yes on flat ground

[billrogers]

************.............BUMP to TOP...........****************

[RUN.10W]

Ha ha yea been a bit lazy due to massive work commitments, I will be out there tomorrow, hopefully might find a problem.

[RUN.10W]

Was playing with the vacuum hose last night and had another hose there so I used to and I have a pedal now, thinking the one way valve is stuffed cause if I put the old hose on no pedal and stalling motor with the new hose I have pedal and the motor doesn't stall, now it's just the pedal goes all the way to the floor re bled the brakes still no good so i know at least have a decent pedal just not pulling me up now lol. Will keep looking into it, discs machined and pads this weekend see if that helps...

[JrZook]

RUN.10W wrote:

, now it's just the pedal goes all the way to the floor re bled the brakes still no good so i know at least have a decent pedal just not pulling me up now lol.

How can you say you have a descent pedal if it still goes all the way to the floor?

Instead of wasting money getting the disc's machined, pads etc etc (unless there completely stuffed) Why not pull the calipers and jam a tight fitting block of wood between them, run the engine and check the pedal. If its still the same you have eliminated the front end. But regardless haven't you capped off teh front end and the pedal was still the same?

Everything you have listed still points to a dodgy mastercylinder and/or air in the system. Also on another note, if it was a new mastercylinder or overhauled dont dismiss it as still the cause of the problem. Just because its new or overhauled doesn't mean its 100%. Ive had this issue in the past.

Dan

[billrogers]

AND THE OUTCOME IS....................................

[RUN.10W]

Ha ha sorry been flat out, the one way valve in the vacuum hose was stuffed, also the calipers I had rebuilt were found to still be faulty so all up it was the vacuum hose and the so called rebuilt calipers which were still faulty so the brakes are all good now.
Thanks for all the help and advice every one.

[ZookiMonsta]

My coily is having the same symptoms as this since I lifted it, I've gone through about 5L of brake fluid trying different things. My rear cylinders had a very slight leak so I have replaced both, the brake pedal is better but still not as good as it should be. I've checked the bleed nipple height compared to the rest of the caliper and it's still the heighest point. I've disconnected the spring that operates the rear proportioning valve as well. There is a very slight 'hissing' sound to be heard when compressing the brake pedal but you really do have to listen to it ie: it's very hard to hear when the engine is going... is this out of the ordinary. Can any body help?

[tanshi]

hissing sounds like a dead booster too me.

[steak_knife]

tanshi wrote:

hissing sounds like a dead booster too me.

Concur