So I was driving the corolla the other day to work when my brake pedal started acting up. I would push down and it would slow down but then lose pressure entirely, with pressure returning every few seconds and going away again. Eventually I lost all pressure and had to get to work using downshifts + handbrake.

My first thought was master cylinder and when u got back home to check, sure enough there was a ton of brake fluid between the mc and brake booster and the booster was all rusted when i removed the mc. My buddy had a brake booster lying around so I replaced mine with that and got a new mc from an auto parts store.

Mc was bench bled and seemed to have good pressure. I installed it and brakes had no pressure. I bled it once attached. No pressure. Then I jacked up the car and tried vacuum bleeding the calipers. No pressure, no fluid either.

Think theres a blocked line somewhere? I dont think one blocked line could affect all the brakes right? Brake lines look fine under the car. Any ideas?

Does your brake fluid empty out? Check for leaks.
I'm also having brake problem too, i think mine might have a leak somewhere, i trace the brake lines, and no signs of leaking. I would fill up the brake fluid tank and it would be empty in like 3 days. Anyone have these difficulties?

Nope, fluid stays level

See that little adjustable rod that comes out of the booster & pushes the MC?
It's too long & its piston's seals are blocking the reservoir ports. Fluid should flow freely into & out of it.

It's too long? I know which piece youre talking about, but why would It be too long?

I guess more importantly what do I do about that. Thanks for your help

i having the same problem with my 86 but the only thing is that i changed both booster and MC and was able to only get fluid out of the front two wheel and nothing in the back. then i replace the rear rubber brake hose to a new one still no fluid. and finally i decided to get a vac pump to pump it out by force still nothing came out i disconnected the rear hose again and ran brake cleaner thru the rear brake lines to see if it came out the other end and it did. =D but still no fluid would even try to come out i ran it like this for a day and then jacked up the car and inspected that the fluid was leaking out front the rubber hose connecting to the hard line. i wanted to know if theirs anything i can do from getting it from stop leaking thru.

up! thanks in advance for the help

Sounds like the brake fluid is bypassing the master cylinder. I would start there.

lets see...


Brake master, check to see if fluid comes out of all the outlets on it(you are going to need a line wrench), yes? next. no? figure out why, clog or w/e.

follow the brake lines from the MBC, proportioning valve. check to see that fluid comes out of the outlets, no? theres your problem, clogged porp valve.
Yes? keep going...

Pretty much the whole technique here is process of elimination from beginning to end.

If you have original toyota fluid in there(from when the car was built) its time to change it.
Do not be lazy, be methodical and take your time. I prolly dont need to explain why brakes are important.

worked on it last night but couldnt update until now. barely any pressure out of the rear port on the master cyl. Was wondering if this could be from the threaded bracket on the booster(as mentioned above) being in the wrong place and could cause pressure to be lost on only one of the outlets?

Edit: thanks for the above post, didnt see that. So yeah, apparently stuck at step one. Ill try adjusting the brake booster bracket, as my buddy did it the first time so im unsure if it's threaded to the same lengh

Is this a brand new m/c or a reman unit?

It's a reman. Ive returned/replaced it with another just to make sure but still same. I guess two could have been broken outta the box..

So I adjusted the brake booster bracket, threading it a bit farther in. This seemed to help the rear outlet on the bmc to get some more pressure. Both mc outlets now seem to have good pressure.

Both outlets on the prop valve bleed just fine.

kuroki86 wrote:So I adjusted the brake booster bracket, threading it a bit farther in. This seemed to help the rear outlet on the bmc to get some more pressure. Both mc outlets now seem to have good pressure.

Both outlets on the prop valve bleed just fine.

Was about to suggest that next cool!

maybe that sounded like it was fixed? it has gotten better than no pressure at all, but still VERY little brake pedal pressure tho...

Tomorrow i'm going to try and blast some carb cleaner through the lines and see if it comes out of the front caliper.

any other suggestions?

blast carb cleaner? About how much pressure from that can compared to what the MC puts out?
Remove the reservoir and look through the ports to see that the pistons seal's have have come back far enough to let fluid freely flow into the MC. Use a soft wire with a blunt end, gently, if you can't see it.

^ aight thanks, ill try that and report back. i meant shoot some carb cleaner thru the lines to see if theres a clog or if it could come out the caliper freely.. idk im out of ideas.

kuroki86 wrote:^ aight thanks, ill try that and report back. i meant shoot some carb cleaner thru the lines to see if theres a clog or if it could come out the caliper freely.. idk im out of ideas.

Use compressed air & a blow tip. Your doin this before or after the porportioning valve?

If carb cleaner is your preference to clear them out, I'd suggest disconnecting the rear caliper lines. You dont want nothing but dot 3 fluid goin thru the calipers as the cleaner will adversely effect the piston seals..they're a bitch to overhaul

KonaTrueno723 wrote:

kuroki86 wrote:^ aight thanks, ill try that and report back. i meant shoot some carb cleaner thru the lines to see if theres a clog or if it could come out the caliper freely.. idk im out of ideas.

Use compressed air & a blow tip. Your doin this before or after the porportioning valve?

If carb cleaner is your preference to clear them out, I'd suggest disconnecting the rear caliper lines. You dont want nothing but dot 3 fluid goin thru the calipers as the cleaner will adversely effect the piston seals..they're a bitch to overhaul

^thanks for the tip, will report back