Very weird braking issue
 

Hey everyone, I am having an odd issue with my 99 limited. I bought the truck with soft/squishy brakes. Took it home and replaced the original MC with a new OEM one, bled the brakes got my peddle back or so i thought.

When backing out of my garage, the peddle sank like it did before, but if I press it a hair faster it is a stiff normal peddle. I have gone through the entire system and there are no leaks but the lines are a little crusty. I have new ones ready to be put in but im wondering what else to try and fix this. I only drive it around the block right now because of the random soft peddle. I am pretty hesistant to blame the MC since it is a brand new OEM replacement (bench bled and all). I've also tried activating ABS to get all the air out. I might try that one more time too..

Idk if you any of you have experienced this before or have an idea for a fix please let me know!

Are your rear brakes adjusted up properly? Is your brake booster and it's check valve working properly?

The goto the floor out of the blue can be the brake booster check valve sticking.

Sent from my SM-A536V using Tapatalk

Did you follow the FSM procedure for bleeding the master cylinder? It's different than normal bench bleeding.

Rears are adjusted correctly that I know for sure! I didnt know about the check valve. Assuming it is cheap I might just replace it. Brake booster works fine tho, or at least I think it is

Do you have a link? I can never find the FSM for 96-00. All my FSMs have the electronic MC procedures

This post shows the procedure. There's a valve in the master cylinder that will only bleed if you follow the FSM procedure. No clue on the valve's purpose or function.

https://www.toyota-4runner.org/3547783-post14.html

Here's the picture directly:

https://i.imgur.com/BFS1dvk.jpg

The little extra tube on the side of the master cylinder helps with brake feel with the rear drums. It has to be 'set' correctly with the above procedure (and bleeding has to happen in the right order) to make it work - otherwise no pedal pressure...

-Charlie

Do you have any bearing play in front wheels?

Thanks for the links and pictures! The MC was bled using this procedure. I dont have any play in the front wheel bearings as well. Looking through forum posts and 3rd gen mafia facebook posts, it seems like this is has happened to other people. Just no definitive solution that I can find.

If it helps, when the peddle does go to the floor, it seems like its only the front engage, but when its working correctly I feel all 4 brakes solidly slow.

If I had to guess it's your ABS pump. I had the same issue where i'd pretty much have to have the brake pedal on the floor before the brakes started working. Replaced a ton of stuff and did everything mentioned here and nothing fixed it. Went and got a junkyard ABS pump and put it in and brake pedal was fixed. Idk what was wrong with it but something was.

Had a very similar issue with my 00' limited and it turned out it was the brake booster.

Sent from my SM-F936U using Tapatalk

I have done this, I cant remember the forum title but it was one of the first things I found and tried. My ABS works fine, as I have taken it down some dirt roads to try and pump out any residual air. So I would like to check that as ok.

Any idea what could cause that? Or any way to check the brake booster before replacing? I always thought a failed booster results in a stiff pedal.