Mushy brakes

[JTS197]

Hello Everyone.

The brakes on my 4Runner seem to have gone really mushy recently. I have been searching throughout this forum (and others) to see how best to troubleshoot this.

There seems to be a good amount of distance, when I press on the brake pedal, before the brakes actually start to catch. It was not like this a few months ago, and it seems like it has gotten worse. From what I read, it sounds like if I replace the entire master cylinder/abs pump assembly, that should fix it. But I am not ready to spend $2k on it yet.

I see some Toyota part sites sell the master cylinder separately from the abs pump assembly. I am wanting to replace the abs pump assembly and/or just the accumulator (since it is cheaper than the MC). I am not sure if it is the problem.

I can hear the pump turn on when I first start up. And it cuts off after maybe 5-7 seconds. But when I press on the brakes, they feel really mushy. If I hit the brakes 3 times in a row, the pump comes back on (is that normal?).

Could it be just the accumulator leaking? How many time should I be able to hit the brakes before the pump starts again?

Thanks,

JT

 

[81runner]

Hello Everyone.

The brakes on my 4Runner seem to have gone really mushy recently. I have been searching throughout this forum (and others) to see how best to troubleshoot this.

There seems to be a good amount of distance, when I press on the brake pedal, before the brakes actually start to catch. It was not like this a few months ago, and it seems like it has gotten worse. From what I read, it sounds like if I replace the entire master cylinder/abs pump assembly, that should fix it. But I am not ready to spend $2k on it yet.

I see some Toyota part sites sell the master cylinder separately from the abs pump assembly. I am wanting to replace the abs pump assembly and/or just the accumulator (since it is cheaper than the MC). I am not sure if it is the problem.

I can hear the pump turn on when I first start up. And it cuts off after maybe 5-7 seconds. But when I press on the brakes, they feel really mushy. If I hit the brakes 3 times in a row, the pump comes back on (is that normal?).

Could it be just the accumulator leaking? How many time should I be able to hit the brakes before the pump starts again?

Thanks,

JT

I would replace the brake fluid first. Easier and cheaper. Plus, contaminated brake fluid will cause braking power to suffer dramatically.

 

[rdruss]

Yes, I would try easy things first. Bleed all the brakes extensively, fill a baby food jar from each caliper.
Check your pads for wear.

 

[Keros]

I had issues in... all the calipers... with some combination of pistons being jammed in some way or another on every single caliper. And the brake pedal had all the feel of mashed potatoes.

Likely that it took substantially more force to move the pads onto the disks, so it'd take alot of brake pedal force to engage the brakes.

Yeah, so lesson learned there was CENTRIC is bad, mmmkay.

 

[AuSeeker]

Hello Everyone.

The brakes on my 4Runner seem to have gone really mushy recently. I have been searching throughout this forum (and others) to see how best to troubleshoot this.

There seems to be a good amount of distance, when I press on the brake pedal, before the brakes actually start to catch. It was not like this a few months ago, and it seems like it has gotten worse. From what I read, it sounds like if I replace the entire master cylinder/abs pump assembly, that should fix it. But I am not ready to spend $2k on it yet.

I see some Toyota part sites sell the master cylinder separately from the abs pump assembly. I am wanting to replace the abs pump assembly and/or just the accumulator (since it is cheaper than the MC). I am not sure if it is the problem.

I can hear the pump turn on when I first start up. And it cuts off after maybe 5-7 seconds. But when I press on the brakes, they feel really mushy. If I hit the brakes 3 times in a row, the pump comes back on (is that normal?).

Could it be just the accumulator leaking? How many time should I be able to hit the brakes before the pump starts again?

Thanks,

JT

From your description your pump is working as it should, I would do as the others have mentioned and check the rest of the system, especially flushing out the old brake fluid and replacing with new fluid, but first check to make sure that all of your calipers are working correctly and not seized or partially seized, replace any that aren't working as they should.

 

[MikeinNH67]

Front calipers fixed mine, I did do the rotors and pads at the same time.

 

[tbaygents]

Same mushy feeling here, both front calipers had frozen pistons. Changed pistons, bled the lines and all is good!

 

[JTS197]

Thanks everyone. I know the front calipers were changed maybe 80k miles ago; sounds like I need to check them again.

 

[81runner]

All the seizing calipers are a result of bad brake fluid. Water ingresses the fluid, which in addition to making your braking power suck eggs, corrodes the inside of the caliper and piston until it seizes. I think Toyota recommends changing brake fluid like every 2 or 3 years, I remember reading somewhere. Fluid is ALWAYS cheaper than iron. Ounce of prevention vs pound of cure...ok I'll get off my soap box now lol