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I have problem with my brakes... this has stumped everyone who i have asked even toyota.

After i replaced the rotors (slotted 4000 series) and pads (bendix 4wd) on the front i found the pedal pushed all the way to the floor.

So i bled the brakes, using a different colour brake fluid until the new colour came through at all 4 wheels.

This still didn’t fix the problem. So i presumed the pads just needing to be bedded in. After 2000km and some very careful driving it hasn’t gotten any better...
So the problem from the start.
When the car is off - no vacuum
The pedal is extremely firm and cannot be moved no matter how hard you push. It seems like the brake would work perfectly.

Once the engine is started and the brakes have vacuum the pedal pushes all the way to the floor. With about 50% braking force like there is an airlock in the lines. However, if you pump the pedal to compress the airlock the pedal simply continues to push to the floor. Like fluid is passing back past the seals in the master cylinder.

Last week it was taken into Toyota for a test drive, the head mechanic was convinced it was the master cylinder. Winner i thought only $600 for a new one and i would have good brakes.

today they replaced the master cylinder... and walaaa still the same problem now Toyota are ordering in another brake master cylinder as they are concerned that the master cylinder they ordered could be faulty.

Has anyone ever experienced this and found the fix as i am concerned that the problem may be outside the Master cylinder... What is the chance that i would get a brand new farked master cylinder?

Just a guess, but check the vacuum line between the master cylinder booster to the engine driven vacuum pump which is located under the power steering reservoir. It runs around the firewall in a metal pipe and there is rubber hose each end.

I'd also be checking the vacuum pump out to confirm it is working if the pipe is OK.

If it is disconnected or leaking anywhere, there will be no power brakes. Hopefully the mechanics would pick this fault.

thanks rod. it is making good vacuum doesn't seem to be leaking. it has me stumped... im not sure what it could be.

To find out if it is master cylinder or front or rear brake issue, clamp off front and rear flex hoses and check brake pedal, if pedal still fades it is master cylinder. If no pedal fade release one clamp at a time and recheck pedal, this will tell you if it is front left or right or both fronts or rears.
Hope this helps

there's been a couple of instances on here in the past with people with similar issues..

- First one was pedal dropping to floor, they could pump it up to stop, but it would drop to the floor again next time they wanted to use it.. ended up being that one of the discs on the front was not on correctly and causing the caliper to push back in from excessive movement..

- second one was similar issue, but ended up being that you need to bleed the brakes in the correct order, remembering that pre 2010 models have the LPV that needs bleeding as well as the 4 corners.. the air was trapped in the LPV causing the problem..

Steve

Have this problem with some landcrusers, not going all the way to the floor but just not a good pedal. Usually have to
re-bleed a couple of times over 500 kms get air out of rear load valve bleeder. First time I struck it I near re built the brake system till the guys at the re sleavers told me it happens.

I very much doubt it's in the master cylinder, if Toyota bled your brakes properly and the pedal is still shit, I reckon find a cheap 2nd/h or borrow someone's booster and try it. Maybe booster diaphragm is leaking,

If you have a new master cylinder fitted the chances of it having the same problem are equal to me winning lotto.
The problem has been there since you replaced the rotors yourself? My guess...air in system...or as someone else suggested there is excessive travel in the caliper pistons due to new rotors not being installed properly.

How can the rotors not be installed properly. Don't they just slide on the hub.

Maybe a silly question, but do you have ABS? If you do you'll have to bleed the brakes while cycling the ABS solenoids. You can use Techstream to do this. I had similar issues after letting the master cylinder empty while bleeding, but after cycling the solenoids, they bled well and have a good hard pedal with vacuum.

But surely Toyota would know this???