Brake pedal almost goes to floor to stop

Recently my brakes on my 2007 Tacoma pre runner, have been getting worse and worse. I’ve checked the, master cylinder, lines, pads, rotors, and everything is good. Bled all the air out of the lines. No leakes in the brake system. My brakes just aren't stopping as good as they used to. And I almost have to push the pedal to the floor to stop. I don’t know what else it could be.

Any input is greatly appreciated.

 

The brake booster or master cylinder might be going out. Look around there and make sure the vacuum hoses going to the booster are good.

 

adjust the rear shoes

 

This is a good place to start.

ADJUST REAR DRUM BRAKE SHOE CLEARANCE

(a) Provisionally install the hub nuts.
(b) Remove the hole plug, and turn the adjuster to expand the shoe until the drum locks.
(c) Using a screwdriver, release the adjuster 15 notches.
(d) Install the hole plug.

 

Brake booster and master cylinder are all good.

 

I’ll give it a shot. If this doesn’t help is there anything else it could be?

 

If the brake booster and master cylinder are all good and you are positive there is no air in the system. I don't know other than the adjustment of the rear brakes.

 

When you bled the air out, did you replace all of the fluid? Old brake fluid will absorb moisture. Under pressure that moisture turns to vapor, which compresses. This could easily be your problem.

 

First, how do you know the master cylinder is good? Did it tell you so?

If in fact the master cylinder is fine, rear shoe adjustment is correct, a faulty ABS module WILL also cause excessive brake pedal travel.

Oh, and I see you said nothing about the condition of the rear brake shoes or wheel cylinders, pull the drums, check the shoes, and pull back the boot on the wheel cylinders (each side) and look for fluid leaks.

 

Based on what you've described, the Master Cylinder is most likely suspect. Just because it doesn't show signs of leaks doesn't mean it's good. I'm not sure how you determined that it was good, but the seals and or valving are probably bad. If everything else in the system appears fine, the master cylinder would be the first thing I would change. It's the most common reason for mushy feeling brakes and or the pedal going to the floor.

 

I had to replace my master cylinder once; $1,200...

 

X2 it's the master or the booster. Not sure how you determine those are "good" with a spongy pedal, especially if you've gotten all the air out of the system like you say.

Try rear brake adjustment, try bleeding one more time, if not it pretty much has to be the master...have you checked all the lines for leaks?

 

Start simple. Do a full fluid flush and adjust the rear brakes. Even if you've used the parking brake every day, there's a chance the self-adjustment is off. If you don't use your parking brake every day, they aren't self-adjusting.

If those two things don't do it, then look into diagnosing the MC and booster. But adjusting the rear brakes and flushing the fluid are normal maintenance you should be doing anyway.

 

Have you looked at the rubber brake lines? They can get soft and expand with pressure giving a soft feeling pedal. Worn / slack rear shoes are most likely for a low pedal though. Our NYS inspection station flagged the soft lines on an 06 BMW for cracks and deterioration,but no leaks. We replaced them with some kind of red colored braided steel aftermarket lines and the pedal feel was much better.

 

Agreed with adjusting the rear brakes first. Then, if that doesn't correct the problem...

Pinch off the rubber brake hoses going to each wheel. If pedal feel is restored, then the issue is at one of the wheels. Remove the clamp, one wheel at a time, rechecking pedal feel each time. When you remove a clamp and the pedal feel goes to shit; that's your suspect.

If pinching off all four hoses does not restore the brake pedal; then the problem is upstream; either master cylinder or ABS unit. You can plug off the ports to the master cylinder; same results expected - if pedal feel is restored, then the issue is in the ABS unit. If pedal feel is still low/spongy, the problem is the master cylinder.

Don't use vice grips or pliers to pinch off the lines. They make clamps just for brake hoses:

$10 Lisle 22850 Hose Pincher

https://www.amazon.com/Lisle-22850-Hose-Pincher/dp/B0002NYB78


Let us know what you find.

 

I took of the lines running to the master cylinder and screwed in caps and pushed on the brake pedal and it stayed firm, and didn’t sink.

 

I have metal brake lines, and no kinks in them. I readjusted the rear brakes and that seems to have helped a little. My next move is to completely flush out the old fluid with new.

 

Replaced shoes 15k ago looked at them today and they are fine.

 

I checked master cylinder by screwing in caps, to where the lines go into the cylinder. Next I pushed on the brake pedal, didn’t sink at all and was very firm. Booster can’t be bad cause if I pump up my brakes while the car is off, and then hold the pedal down while I turn on the car the pedal goes down easy

 

There is a rubber hose at each caliper and two at the rear axle (one for each wheel cylinder). If there wasn't, those metal pipes would break from flexing.

I thought you already flushed the fluid? Nope, re-read and saw you just bled the system. Flush it and see where you're at.