Spongy brakes after replacing part of steel brake tubes

[z_johnq]

Hi,

Part of my 1996 LC's brake lines was leaking owing to some tiny rust holes (I guess I had moisture in the fluid). I replaced with a piece of flared tube. But the tube that I used is slightly longer than the original that I cut off. It's hard to have exactly the same length of it. Not sure if it has something to do with the spongy brakes.

I bled the brakes after doing "bench bleeding", which was not the real bench bleeding: I left the MC on the car but unscrewed the connector on top of MC, blocked with a stud; replacing the one on the side with a bleeding connector and a plastic tube. It had tiny air bubbles at first but after quite a few pumps of the brake pedal, no more air bubbles.

I asked my wife to press the pedal. I bled 3 to 4 times for each brake, starting from the rear one on passenger side.

I saw some air coming out of bleeding valves but not much. It feels a little bit better than before the bleeding but still it goes all the way to the floor.

Not sure if it's true or not. I had a 92 LC before. It had never had these problems: the exhaust system last life time; no brake line problems (even I saw some obvious cracks on the rubber brake hose but still held). But on the 96 LC, about 80% of exhaust has been replaced; so are the Oxygen sensors and more. I got an impression that the steel parts of the car have a stronger tendency of rusting than the old model.

Thanks in advance.

z_johnq

 

[tjtfaulkner]

I do not fully understand what you are explaining, but i know the longer pipe will make no difference. if the pedal is going to the floor it is either leaking fluid somewhere or there is still air in the system, there can be a bleed valve on the rear load sensing valve above the rear axle. i hope you understand what i mean.

 

[frank rabbets]

Yes the length of the pipe will make no difference. Sometimes a rest overnight will help the little bubbles become one big one and it sometimes comes out easier. It sometimes helps to have two people. The nipples should be held open on the downward stroke of the brake pedal. The person in charge of the nipple closes it then says "up" to the brake person who then lets the pedal up. This way only fresh fluid is taken into the system.

 

[adrianr]

Ive never (yet) tried it on the landcruiser but it should work ok. For my VW Golf I just bought and used a Sealey pressure bleeder. Had to replace a faulty ABS pump. using the pressure bleeder i replaced all brake fluid and bled full system including the abs pump very easily and quite quickly on my own. Great piece of kit. added about 2.5 litres of fresh brake fluid to the container. make sure the screw caps are on very tight, one on the sealey unit and the other the Sealey units cap that screws onto the brake fluid reservoir on the car. pump it up to 12 psi and then bleed the 4 corners and the bias adjuster under the back, starting the furthest away from the master cycling and working your way back to it. Popping back after each bleed nipple to check level of fluid in the sealey unit and to pump as required to maintain 12 psi. (Interestingly on the golf VW recommend the other way starting nearest and ending farthest. pushes the fluid out quickly, its worth replacing the brake fluid if it has not been done.

 

[z_johnq]

spongy brakes after replacing the part of the brake lines

Thanks folks for your info, which is quite helpful.

1) I don't eye-ball any leaking along the brake lines, unless the fittings on the replaced leak air/oil.

2) I tried to bleed the air, if any, using a pneumatic vacuum bleeder (the one with some high-power compressor; mine is a 30 gallon 5 HP Craftsman one, which should be good enough for the job) but the brake function has little improvement. I did it with and without engine running, as you guys suggested. As the bleeding is carried on, air comes out of the calipers into the plastic tubes continuously. I checked the reviews of the device. Most of the users experienced air coming out at the beginning but soon it will be gone. That's not what I got.

3) I guess the MC needs rebuilding.

4) or the calipers need replacement. The car has shy of 150K miles on it and the brake fluid had never been changed.

What'd you guys think? Btw, I used a Quick Reply a few days ago but it looks like it did not go through.

Thanks again.

z_johnq