Seemingly never ending sinking brake pedal issue

[m0ist]

Hey guys, love the forum and all the information in it. I have a question regarding a brake issue that I've had since I bought the car (about a month ago now).

The brake pedal sinks to the floor.

I started by replacing the following:
Front pads and rotors
Rear shoes and drums
Wheel cylinders
Brake fluid flush and bleed

Still the pedal goes to the floor.

Thinking it had to be the master cylinder, I replaced it.

Still, the pedal goes all the way to the floor. Everything was bled correctly.

The truck is equipped with abs. Is it possible that air got into the abs module somehow and it's screwing up my brakes?

Im just really confused at this point and I'm tired of throwing money at the dang brakes lol. Any help would be greatly appreciated!

 

[kolelt]

Have you adjusted the rear brakes? If your rear brakes are out of adjustment. The pedal will feel like poop. Behind the wheel, there is a little opening. And you need to jack up the rear. And start adjusting the brakes till you have a hard time spinning the wheel by hand.

 

[HiLife]

You may still have air pockets in the master cylinder and/or abs.
Did you bleed the master cylinder first before bleeding the wheel cylinders and calipers?
The laymans way of releasing air in the abs is allowing the abs motor to cycle on a rocky, dirt or wet road, then bleed the wheel cylinders and calipers. Repeat until you get a firm pedal.
Or, bring it to a shop where they can use a abs tool to cycle the abs while the truck is sitting still.

 

[SJC4Runner]

I went through a similar problem. From your description of you problem, you have probably failed to bleed the brakes.

Here is what I went through on my issue.
http://www.toyota-4runner.org/3rd-gen-t4rs/180460-bench-bleeding-master-cylinder-2.html

Not having the tool to activate your ABS while bleeding basically means it's a royal P.I.T.A.

Also try turning the turning the truck on while bleeding the brakes, make sure your chocking your tires.

 

[BrianSD_42]

Sounds like the description of what happened to me when my callipers broke.

 

[JRZEE2000TR4LTD]

The easiest thing to do is readjust the rear brakes first before going through the brake bleeding process over and over. The last 2 times my brake pedal was down was because of this. Happened after wheeling trips in which mud got in the drum area and self adjusted and then when the mud was gone I had a mushy pedal. Was kinda of a scary 2 hour ride home.

 

[ZionXIX]

I too have been dealing with awful brake pedal feel for nearly 2 years now. Today I fixed one of my rear cylinders and adjusted the rear brakes until I heard the drum scraping on the shoes. I still have an awful pedal feel. New rotors, pads, rear central brake hose. Bled several times. When adjusting the shoes how much is too much? If I adjust them to the point where turning is difficult, wont they rub and wear out the shoes?

 

[JRZEE2000TR4LTD]

I too have been dealing with awful brake pedal feel for nearly 2 years now. Today I fixed one of my rear cylinders and adjusted the rear brakes until I heard the drum scraping on the shoes. I still have an awful pedal feel. New rotors, pads, rear central brake hose. Bled several times. When adjusting the shoes how much is too much? If I adjust them to the point where turning is difficult, wont they rub and wear out the shoes?

Well, if the adjusters aren't stuck they will adjust, but when you adjust them you adjust them until the brake drum hits the shoes not until the wheel is "difficult" to turn.

 

[kolelt]

I adjust them to the point where I can't spin them by hand. Driving around a little will make the pads be cunt hair away from rotor. And your ebrake will engage right away.

 

[m0ist]

Thanks for all the replies guys. The rears were adjusted to the point where the shoe was scraping the drum. I wouldn't say they are difficult to turn, but they were definitely touching the drum.

I know these things are self adjusting, but you need the ebrake to work right? My ebrake does not work.

It looks like the arm thing that connect in the drum (both sides) are seized up. This shouldn't affect the rear braking though right?

 

[19963.4lsr5]

Thanks for all the replies guys. The rears were adjusted to the point where the shoe was scraping the drum. I wouldn't say they are difficult to turn, but they were definitely touching the drum.



I know these things are self adjusting, but you need the ebrake to work right? My ebrake does not work.



It looks like the arm thing that connect in the drum (both sides) are seized up. This shouldn't affect the rear braking though right?

To me they both need to be operating properly to adjust the rear brakes. That bolt on the ebrake arms has a clearance adjustment.


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[nevada]

Thanks for all the replies guys. The rears were adjusted to the point where the shoe was scraping the drum. I wouldn't say they are difficult to turn, but they were definitely touching the drum.

I know these things are self adjusting, but you need the ebrake to work right? My ebrake does not work.

It looks like the arm thing that connect in the drum (both sides) are seized up. This shouldn't affect the rear braking though right?

does the pedal pump up?

adjust the rear brakes until you cannot turn the drum, then back it off a few clicks.

 

[Buckaroo]

Thanks for all the replies guys. The rears were adjusted to the point where the shoe was scraping the drum. I wouldn't say they are difficult to turn, but they were definitely touching the drum.

I know these things are self adjusting, but you need the ebrake to work right? My ebrake does not work.

It looks like the arm thing that connect in the drum (both sides) are seized up. This shouldn't affect the rear braking though right?

I think the part that you are saying is seized up is the bell crank - problem is very common. You can replace them - did so myself and used Dorman part #924753.

Inoperable E-brake will not cause an issue other than the obvious - can't set the E-brake and can't readjust the rear brake shoes using the E-brake. Can still adjust the rear brake shoes manually. Other than that, and assuming bell cranks aren't frozen in the "applied" position, brakes still work normally....

Buckaroo

 

[DK327]

I also have the same symptoms ever since I got the truck last Feb, granted I did NOT bleed the rear breaks but did the fronts after TBU upgrade. Soft brake pedal and e-brake not operational.

 

[Buckaroo]

I also have the same symptoms ever since I got the truck last Feb, granted I did NOT bleed the rear breaks but did the fronts after TBU upgrade. Soft brake pedal and e-brake not operational.

If the E-brake is not operational or you are rarely applying it (my situation), you need to periodically adjust the rear brakes manually. If the rear brake shoes move too far away from the drum as they wear, the shoes will not hit the drum until the pedal has gone down a long ways. If the distance between the shoes and the drum is too great, the brake pedal may bottom out before they fully seat. No amount of bleeding will correct this problem. That said, unless the brake pedal is bottoming out on the floorboard, the brake pedal should be firm but just have too much travel under this condition. If the brakes are "mushy" (aka soft, spongy, not firm), that is typically an issue with air in the lines. If it isn't too bad, you can pump them several times and they will momentarily firm up. That is a bleeding issue. If the pedal firms up but then slowly sinks to the floor, that is typically a master cylinder bypass (or master cylinder seal) issue which requires replacement or rebuild of the master cylinder.

Buckaroo

 

[m0ist]

If the E-brake is not operational or you are rarely applying it (my situation), you need to periodically adjust the rear brakes manually. If the rear brake shoes move too far away from the drum as they wear, the shoes will not hit the drum until the pedal has gone down a long ways. If the distance between the shoes and the drum is too great, the brake pedal may bottom out before they fully seat. No amount of bleeding will correct this problem. That said, unless the brake pedal is bottoming out on the floorboard, the brake pedal should be firm but just have too much travel under this condition. If the brakes are "mushy" (aka soft, spongy, not firm), that is typically an issue with air in the lines. If it isn't too bad, you can pump them several times and they will momentarily firm up. That is a bleeding issue. If the pedal firms up but then slowly sinks to the floor, that is typically a master cylinder bypass (or master cylinder seal) issue which requires replacement or rebuild of the master cylinder.

Buckaroo

Thanks for the reply. I should have mentioned this right from the beginning. The pedal does feel spongy. I can pump the brakes to firm the pedal, however it doesn't make the stopping any better. It only firms the pedal up lol.

I am pretty certain that I bled all the air out of the system. At this point I have all new fluid in my brake system (from bleeding so many times).

I will adjust the rears a little further so I can barely move the wheel when its off the ground. When I did the wheel cylinders/shoes I could hear the shoes grinding on the drum.

 

[19963.4lsr5]

Look at your rubber lines for cracks also. If there cracked they will swell instead of applying the pressure to the brake system.


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[Buckaroo]

If you have the shoes adjusted so you can hear them scraping on the drum and you can feel it, that should be good enough. Bleeding is not rocket science but you need to make sure:

1. The reservoir does not get too low - sucks in air.
2. Do the right (passenger side) rear first, then the left rear, then the right front, then the left front.
3. Put tubing over the bleeder and feed it into a bottle containing some brake fluid - keep the end of the tubing below the fluid level in the bottle.
4. Have friend put light, steady pressure on pedal - you open the bleeder (using open end wrench so the tubing stays on the bleeder), the pedal should go down and fluid flows into the bottle. Tell your buddy to yell out when the pedal gets 3/4 way down and you tighten the bleeder before he lets his foot up. Too much pressure on the pedal can cause very small bubbles that are difficult to remove. Pushing the pedal to the floor can hose up the seals in the master cylinder as the piston goes past it's normal travel - maybe put your foot or a 2x4 under the pedal to make sure that doesn't happen. Hose up the seals and then you have another problem...you get to replace the master cylinder.
5. Repeat until no bubbles and then move on to the next wheel.

Another approach is to crack the bleeders on all four wheels and let them drip slowly for 12-24 hours (called gravity bleeding) - make sure all four wheels are dripping. Must keep reservoir from going dry. Takes some time but it is supposed to be relatively fool-proof but have not done it myself.

Buckaroo

 

[m0ist]

Look at your rubber lines for cracks also. If there cracked they will swell instead of applying the pressure to the brake system.


Sent from my iPhone using Tapatalk

If you have the shoes adjusted so you can hear them scraping on the drum and you can feel it, that should be good enough. Bleeding is not rocket science but you need to make sure:

1. The reservoir does not get too low - sucks in air.
2. Do the right (passenger side) rear first, then the left rear, then the right front, then the left front.
3. Put tubing over the bleeder and feed it into a bottle containing some brake fluid - keep the end of the tubing below the fluid level in the bottle.
4. Have friend put light, steady pressure on pedal - you open the bleeder (using open end wrench so the tubing stays on the bleeder), the pedal should go down and fluid flows into the bottle. Tell your buddy to yell out when the pedal gets 3/4 way down and you tighten the bleeder before he lets his foot up. Too much pressure on the pedal can cause very small bubbles that are difficult to remove. Pushing the pedal to the floor can hose up the seals in the master cylinder as the piston goes past it's normal travel - maybe put your foot or a 2x4 under the pedal to make sure that doesn't happen. Hose up the seals and then you have another problem...you get to replace the master cylinder.
5. Repeat until no bubbles and then move on to the next wheel.

Another approach is to crack the bleeders on all four wheels and let them drip slowly for 12-24 hours (called gravity bleeding) - make sure all four wheels are dripping. Must keep reservoir from going dry. Takes some time but it is supposed to be relatively fool-proof but have not done it myself.

Buckaroo

No leaks that I can see. Lines all look dry. Fluid was bled properly each time & I have a new master cylinder:ybrick:.

 

[jkeith.w]

No leaks that I can see. Lines all look dry. Fluid was bled properly each time & I have a new master cylinder:ybrick:.

I hear ya - professional car guy (shop owner) since '02; still have an issue with my 3rd gen brakes. - convinced it's the ABS pump...