Bad Master Cylinder?

[telum01]

I've checked through some old threads and I want to make sure I've got this right since apparently a new MC is $2k :/

A couple days ago my brakes gave out while driving. They were perfectly fine on my drive to work. I left to run an errand at lunch, and they had no stopping power to them - the brake pedal went to the floor. I came to a red light and barely stopped, and sitting there with the brake pressed in, the engine at idle overpowered the brakes and I crept forward. I had to pop back and forth between drive and neutral in order to come to a stop, and even in neutral I had to continuously pump the brakes to stop at all.

I just tried bleeding the brakes (with the ignition on) and it seemed pretty routine. The brakes feel a little better, but still very weak compared to how they should feel. When at a complete stop, in drive, the brakes work, but the brake pedal will slowly sink to the floor.

So what gives? Is it the MC? The problem occurred out of nowhere, without warning, and $2k is a ridiculous amount of money for just the part alone!

Thoughts?

 

[gm350reratliff]

Sounds like the booster pump died. There have been some threads on here lately on how to (possibly) fix the booster pump on the cheap. There was also a complete MC on here for sale for pretty cheap. Good luck!

 

[telum01]

Thanks, I'll look into that, too.

Btw, there aren't any warning lights, no buzzer... except while I was bleeding them, but shut off as I closed up each bleed nipple.

 

[Hawaiian Hillbilly]

first off I'm glad no one got hurt and you made it to your destination. do you hear your booster pump go on when you hit the key on? if you can hear the pump cycle for around 8-15 seconds your pump is working and it may be another part of the master. ive heard of o rings going out etc. very hard to diagnose which is why Toyota will want to change the entire master. if it does not go on with the key then you will need to rip it apart or replace it. hard part on these is its almost impossible to find good parts for the master. I had a very similar thing on my wifes T4R last week. the repair costs are extremely outrageous. I FEL YOUR PAIN! however I was able to get it running again. http://www.toyota-4runner.org/4th-gen-t4rs/225205-2003-v8-brake-booster-pump-diy-fix.html this may help you out. I lucked out and was relieved when I heard it run again. mahalos, HH

 

[LTDSC]

having an 03 and 160k miles, this scares me.

 

[telum01]

first off I'm glad no one got hurt and you made it to your destination. do you hear your booster pump go on when you hit the key on? if you can hear the pump cycle for around 8-15 seconds your pump is working and it may be another part of the master. ive heard of o rings going out etc. very hard to diagnose which is why Toyota will want to change the entire master. if it does not go on with the key then you will need to rip it apart or replace it. hard part on these is its almost impossible to find good parts for the master. I had a very similar thing on my wifes T4R last week. the repair costs are extremely outrageous. I FEL YOUR PAIN! however I was able to get it running again. http://www.toyota-4runner.org/4th-gen-t4rs/225205-2003-v8-brake-booster-pump-diy-fix.html this may help you out. I lucked out and was relieved when I heard it run again. mahalos, HH

I'll give it a shot! Thanks so much!

having an 03 and 160k miles, this scares me.

Yep, I'm pretty pissed off about this. It's a SERIOUS safety issue. I was incredibly lucky to manage it and make it home without incident.

 

[Hawaiian Hillbilly]

having an 03 and 160k miles, this scares me.

yea man these things are crazy expensive. its on my wifes 03 with 271k miles on it so I was expecting the worst. thankfully it worked out. aloha, HH

 

[BlackWorksInc]

It sounds like the hydraulic has failed, that's unfortunate. They are not very cheap items I realize.

 

[telum01]

I got a new MC and installed it. Got the part at wholesale and installation was really easy between me and my buddy. But it's definitely not bleeding properly. The brakes only work when the pedal is pressed to the floor, and anything less does nothing. Everything I'm seeing online points to needing a dealership to plug in Toyota's proprietary software to cycle the ABS to bleed it. Figured I'd reach out one more time on here to see if there's a way to do this myself or if I'm stuck. I've got an Autel 802 as well as ELM327 software, not sure if either of them has the ABS-cycling functionality, though.

 

[DMV4runner]

Hi,
Ran into a similar problem last month doing the 5th gen upgrade. I accidently let my MC run dry. I used info posted here to bleed it and get it right. I don't have access to the link via my phone, but search on bleeding your brakes and you'll find it.
It worked for me and kept me from having to visit the dealer.
I don't remember the details, but it was slow delibrate pumps...20 pumps with the car off. Then acc on. Listen for the booster to sound...around 20 seconds...if it doesnt, repeat the process. Then pump your brakes more than 40 times. Open your back right bleeder valve for a few seconds to expell air. Close and repeat the pumping process. I didnt pump with the valve open. The MC did the work for me. Repeat the process LR, RF and LF.
I had to do it a couple of times, but it worked.
I'm in McLean. Let me know if I can help
Hope it works for you.

 

[telum01]

Hi,
Ran into a similar problem last month doing the 5th gen upgrade. I accidently let my MC run dry. I used info posted here to bleed it and get it right. I don't have access to the link via my phone, but search on bleeding your brakes and you'll find it.
It worked for me and kept me from having to visit the dealer.
I don't remember the details, but it was slow delibrate pumps...20 pumps with the car off. Then acc on. Listen for the booster to sound...around 20 seconds...if it doesnt, repeat the process. Then pump your brakes more than 40 times. Open your back right bleeder valve for a few seconds to expell air. Close and repeat the pumping process. I didnt pump with the valve open. The MC did the work for me. Repeat the process LR, RF and LF.
I had to do it a couple of times, but it worked.
I'm in McLean. Let me know if I can help
Hope it works for you.

It worked!!!!!!!

The procedure is some straight-up witchcraft but it did the trick. I went through a ton of brake fluid ($100 of Motul RBF600 hahahaha) but that's cheaper than a tow truck and dealership labor.

I've never seen brake fluid foam come out of a caliper before. Definitely a new experience but hey, I'm back on the road!

Thanks all for the help!

 

[DMV4runner]

Brakes

Glad it worked out for you. I know how you feel because I felt the same way. Enjoy your new stopping power.