low brake pedal

[billkmiami]

How do I improve my brake pedal feel in my 1997 4runner? I have new pads front and back- drums are adjusted properly- no fluid leaks what so ever- the pedal almost goes to the floor before the brakes grab- they still work fine- if I pump the pedal it will improve but then after I release and reapply, the pedal seems to "lose pressure" and the pedal will sink to the floor- The truck has 161K on it (2wd) - I adjusted the pedal under the dash but this did not help at all- any suggestions?

 

[BTO]

Probably a bad master cylinder.

 

[CO_FlyFisher]

:iagree:

Symptoms of a failing master cylinder. Don't drive it like this for too long!!! You don't want to LOSE your brakes when you need them!!!

 

[rjaudi]

Could be a bad master cylinder, but first I would bleed the brakes really well. I had this first time I bleed the brakes. Then I redid the bleeding and they are perfect.

 

[billkmiami]

I am leaning towards the bad master cylinder- 161K on the original part- may try the bleeding first though to see if this helps! most of the mileage is city type driving so it makes sense the master cylinder is just worn out! thanks!

 

[cfranck1]

When stopped at a light or something, pump the pedal a few times to build a little pressure, then hold the pedal down. It should start dropping slowly if it's a bad Master Cyl. It would be leaking past the seals inside the cylinder.

 

[billkmiami]

if I pump the brake pedal at a stop and after pumping it keeps the pressure than what else could it be?

 

[CO_FlyFisher]

That could be air in the system (a fair amount).

 

[Jon]

How do I improve my brake pedal feel in my 1997 4runner? I have new pads front and back- drums are adjusted properly- no fluid leaks what so ever- the pedal almost goes to the floor before the brakes grab- they still work fine- if I pump the pedal it will improve but then after I release and reapply, the pedal seems to "lose pressure" and the pedal will sink to the floor- The truck has 161K on it (2wd) - I adjusted the pedal under the dash but this did not help at all- any suggestions?

You say properly adjusted, but have you tried tightening the rears again and again? I had the same problem. From under the truck on jack stands, tighten the rears till the wheels spin with a little brake rub then tub on the parking brake cable and try spinning again, bet the noise is gone. tighten again repeatedly like that and the pedal will come back. Reasoning behind this is there is so much fluid loss going to the rear that the pedal has to compensate b going to the floor before adequate pressure is applied to the front which are your main stopping power.

 

[assman]

i had this issue also. my front calipers were bad

 

[billkmiami]

replaced the master cylinder this past weekend, bled each brake cylinder/caliper at each wheel- very easy! this solved the problem- brakes still grab a little too low compared to my Taco but they do work excellent- big difference for my 161000 + miles 4-Runner! worth the $300 bucks- bought an original (Japan made) from the dealer vs paying $150 for a Chinese no name brand..........no issues with the install at all!

 

[stever1000]

I'm having the same issue, but replacing the master cylinder did not cure the problem - anyother suggestions?

 

[octanejunkie]

If your MC hold pressure after pumping it then the seals are probably good. Brake fluid is caustic stuff and eats everything, including the rubber hoses eventually. I would do a full bleed of each circuit until you get clean/clear fluid out of each bleeder - there's probably air or other fluids/crap in one of the circuits.

Do this with a friend and make sure to never let the reservoir on the MC run out or you will be starting the bleed over.

Also, never fill your brakes from the caliper/cylinder up to the MC unless the system is new. You don't want to flush junk in the lines up to the MC.

For all the "I have this problem too" as well as the OP

Brakes are one of the easiest and most overlooked systems on a car, yet we trust our lives to them without thinking twice :smow:

Inspect your brake hardware regularly!

Address uneven wear!

Address uneven stopping, pulsing, pulling, noise and vibration!

Balance and install your wheels correctly

Make sure you bed new brakes properly

And most important, don't drive from gas to brake; allow a safe distance between the car in front of you and let off the gas and coast in gear to slow down/shift to lower gear.

 

[phattyduck]

I'm having the same issue, but replacing the master cylinder did not cure the problem - anyother suggestions?

Is the pedal sinking, or just engaging too low?

I would suspect issues with rear brake adjustment or air remaining in the lines.

-Charlie