Corolla brake pedal sinking to the floor - master cylinder?

[jsean]

This is on the ‘05 Corolla. Gradually lost pedal feel on the way back from work last week. Pedal would sink almost to the floor but not quite. Between this and the Armada oil change with particles what not, things seem to be going poorly vehicle related
No visual leaks at the wheel cylinders or the calipers. Jounce hoses look fine. Level in reservoir didn’t drop.
All of which led me to believe it was the master cylinder, so I ordered one off RA.
Swapped it in after work today. I followed the instructions for bench bleeding (keep it level, fill up the reservoir, let them fluid start dripping out of both ports, cap the ports, firmly push the plunger an inch and look for bubbles), verified no bubbles in reservoir and the plunger was stiff except for maybe 1/8” movement.
Got it on the car which was a challenge with the back/rear hard line. Master cylinder did get a little low during getting it in the car - i kept it topped except one time it dropped a hair below the min line.
Tried bleeding the brakes - I have marginally better pedal travel. I’m able to get clean flow of fluid out of the RR, RF and LF bleeders. I’ve gone through about 48oz of brake fluid on the LR bleeder and I still keep getting bubbles.

Anyone have suggestions on how to proceed? I’m completely lost on this one…

 

[ripcord]

Are you bleeding it by yourself? When all else fails, I go get an assistant and do it the old fashioned way.

I also prefer to bench bleed using adapters and clear tubes to gently recirculate fluid from the ports back into the reservoir until no bubbles are observed.

 

[spasm3]

Did you bench bleed the master cylinder before installing it?

Since there is air in the system, does the car have anti-lock brakes?

 

[SammyChevelleTypeS3]

You likely need a partner to help you bleed those brakes really good. Bubble = No Good.
#1)Go back and re-read and make certain you bench bled the new M/C totally per instructions. If in any doubt do it again.
#2) Look over the new M/C and all 4 brake lines and make sure all is connected with no kinks or any leakers. (you saw none so far..)
#3)Bleed the bakes again, starting farthest wheel from M/C and make sure enough goes thru until there are zero bubbles.
#4)Bleed each wheel in order from LR / RR / Front driver side / M/C side.
*Note* Make sure enough fluid goes thru to each wheel so you are not wasting your time. It sure can be a pain and really tough to do alone if one does not have a mini hand vac pump or one of the many "one man bleeder kits."
What you do not want to hear is that it may be possible you have received a bad M/C. (not too likely but....?)
You are using the proper "new/fresh" brake fluid for your car?
Good luck.

 

[ripcord]

Did you bench bleed the master cylinder before installing it?

Since there is air in the system, does the car have anti-lock brakes?

Great point. Jsean, your car may need to have the anti lock brakes activated to get all of the air out of them. If there is air in the ABS module you can go find a dirt road and slam on the brakes to force the ABS activate a few times, then go bled the brakes again.

 

[jsean]

Are you bleeding it by yourself? When all else fails, I go get an assistant and do it the old fashioned way.

I also prefer to bench bleed using adapters and clear tubes to gently recirculate fluid from the ports back into the reservoir until no bubbles are observed.

Wife was playing assistant at the brake pedal, very patiently.
I debated if I should go down the path of adapter/clear tubes but stuck to the m/c manufacturers instructions to use their block off plugs.
Perhaps I need to raise the back of the vehicle up much higher than the front to see if the bubbles will migrate that way?

 

[jsean]

Did you bench bleed the master cylinder before installing it?

Since there is air in the system, does the car have anti-lock brakes?

No ABS on the Corolla. I did bench bleed the master cylinder. I followed the instructions that came with the master cylinder:
1. Put it on a vice and make sure it’s level.
2. Fill up the reservoir and wait a few mins to for the fluid to start dripping consistently out of both the ports.
3. Install the supplied block off plugs to both ports.
4. Press the plunger with a blunt device at most 1”, wait 15-20 seconds and then release gently. Repeat until no bubbles are visible in the reservoir.

At #4 - I couldn’t get the plunger to move more than 1/4” at the start which then reduced to 1/8” at most. I could lean into the plunger, crack open one of the ports - get a steady stream of fluid out and close the port before releasing the plunger.

It’s the one time that I let the reservoir get just below the min line during the vehicle install. But I’d think I’d create an air pocket only if I ran the master cylinder dry, right?

 

[slacktide_bitog]

speed bleeders are awesome

 

[jsean]

Great point. Jsean, your car may need to have the anti lock brakes activated to get all of the air out of them. If there is air in the ABS module you can go find a dirt road and slam on the brakes to force the ABS activate a few times, then go bled the brakes again.

Good point - I’ve done the braking on dirt roads to get the ABS actuated. Thankfully the Corolla has no ABS.

 

[SammyChevelleTypeS3]

I would just hook it all up and have a partner keep the M/C full until you can bleed air out thru each wheel. It may take a while since it sounds like you got air in some way. Not a big deal. You can work it out but it will take a few times flushing to each wheel.

 

[D60]

At #4 - I couldn’t get the plunger to move more than 1/4” at the start which then reduced to 1/8” at most. I could lean into the plunger, crack open one of the ports - get a steady stream of fluid out and close the port before releasing the plunger.

It’s the one time that I let the reservoir get just below the min line during the vehicle install. But I’d think I’d create an air pocket only if I ran the master cylinder dry, right?

This seems odd to me. Not sure what to say but you should get more than 1/4 to 1/8" of movement.

How much can you depress the old one?

I too hoard the kits with clear tubing feeding back to the reservoir. Much prefer that over the stupid plugs (which are cheaper to manufacture and package I'm sure)

Sometimes it can help to slowly pump the pedal three times, hold, then crack the bleeder. Ideally, close bleeder just before the pedal gets to the floor.

You could also try a reverse bleed but you'd have to source the tooling.

You can also try cracking one or more bleeders and gravity bleeding.

It's all a bit superstitious but sometimes one approach works when another does not.

If you have no luck I'm still suspect of your bench bleed.

 

[jsean]

You likely need a partner to help you bleed those brakes really good. Bubble = No Good.
#1)Go back and re-read and make certain you bench bled the new M/C totally per instructions. If in any doubt do it again.
#2) Look over the new M/C and all 4 brake lines and make sure all is connected with no kinks or any leakers. (you saw none so far..)
#3)Bleed the bakes again, starting farthest wheel from M/C and make sure enough goes thru until there are zero bubbles.
#4)Bleed each wheel in order from LR / RR / Front driver side / M/C side.
*Note* Make sure enough fluid goes thru to each wheel so you are not wasting your time. It sure can be a pain and really tough to do alone if one does not have a mini hand vac pump or one of the many "one man bleeder kits."
What you do not want to hear is that it may be possible you have received a bad M/C. (not too likely but....?)
You are using the proper "new/fresh" brake fluid for your car?
Good luck.

Fresh brake fluid only. At this point, it’s basically clear looking fluid coming out of all the bleeders. The M/c on this car is in front of the steering wheel. What perplexes me is that I get a consistent stream out of the RR which is the farthest and the LF and RF. But the LR which is the 2nd farthest from the MC isn’t bleeding correctly.

I’ve gone through two 32oz DOT3 containers and about a quarter of the third container at this point, the bulk of that fluid being cycled through the LR bleeder.

 

[jsean]

This seems odd to me. Not sure what to say but you should get more than 1/4 to 1/8" of movement.

How much can you depress the old one?

I too hoard the kits with clear tubing feeding back to the reservoir. Much prefer that over the stupid plugs (which are cheaper to manufacture and package I'm sure)

Sometimes it can help to slowly pump the pedal three times, hold, then crack the bleeder. Ideally, close bleeder just before the pedal gets to the floor.

You could also try a reverse bleed but you'd have to source the tooling.

You can also try cracking one or more bleeders and gravity bleeding.

It's all a bit superstitious but sometimes one approach works when another does not.

If you have no luck I'm still suspect of your bench bleed.

Those are some good points. I’ll give gravity bleeding a shot tomorrow and see if anything comes out of it.

I’ll also try and check the old m/c to see how much distance I can push the plunger with the ports plugged.

Out of curiosity - if I hadn’t bled the m/c correctly, wouldn’t that have resulted in air leaks on all bleeders or at least in one other bleeder that’s on the same channel as this LR bleeder (I’d guess it’s either RF or RR)?

 

[willbur]

No ABS on an '05 Corolla? My wife's old '04 did...

No ABS on the Corolla. I did bench bleed the master cylinder. I followed the instructions that came with the master cylinder:
1. Put it on a vice and make sure it’s level.
2. Fill up the reservoir and wait a few mins to for the fluid to start dripping consistently out of both the ports.
3. Install the supplied block off plugs to both ports.
4. Press the plunger with a blunt device at most 1”, wait 15-20 seconds and then release gently. Repeat until no bubbles are visible in the reservoir.

At #4 - I couldn’t get the plunger to move more than 1/4” at the start which then reduced to 1/8” at most. I could lean into the plunger, crack open one of the ports - get a steady stream of fluid out and close the port before releasing the plunger.

It’s the one time that I let the reservoir get just below the min line during the vehicle install. But I’d think I’d create an air pocket only if I ran the master cylinder dry, right?

 

[Nukeman7]

Tried bleeding the brakes - I have marginally better pedal travel. I’m able to get clean flow of fluid out of the RR, RF and LF bleeders. I’ve gone through about 48oz of brake fluid on the LR bleeder and I still keep getting bubbles.

Anyone have suggestions on how to proceed? I’m completely lost on this one…

I think there is still trapped air in the LR caliper and/or brake line. I have had good results in similar hard to bleed situations by performing a reverse bleed with a Phoenix Systems V-5 unit which forces the trapped bubbles back into the master cylinder reservoir.

 

[jsean]

No ABS on an '05 Corolla? My wife's old '04 did...

Not on this one. It’s an oddly spec’ed Corolla S. Has the side and curtain airbags which seemed to be a rare option back then but doesn’t have ABS or TPMS.

 

[SatinSilver]

We had an '05 Matrix XR without ABS and no side curtain airbags. I think the MSRP back then was close to $20k. Had it till '21 and 166k miles. Rear brakes were drum.

 

[Donald]

Maybe you need to push on the brake pedal and have wife open up the bleeders?

 

[SammyChevelleTypeS3]

OP mentions somewhere above having the M/C plugs installed? If those plugs were installed (capped?) then the piston will be extremely hard (near impossible) to move. Not understanding why the plugs would be installed (capped) instead of hose run from each back into the reservoir to bench bleed? If the M/C was not kept filled (OP mentioned letting the level drop and M/C moved) and not kept level when hooked up it is very likely air did get into the system and will have to be all bled out again. OP's choice to start all over or attempt to bleed thru M/C to each wheel (may take a while depending on amount of air that got in). Regardless if the M/C is bench bled again and ready for install, the air that is now in the lines still has to be dealt with. Sometimes things like this require backing off. Take a break and think about all that was done or not done before deciding how to continue.

 

[D60]

I had never before even tried to find such a thing but a simple web search revealed most FLAPS likely carry a Dorman bench bleed kit with the tubes as God intended -- part 14151

There are knockoffs on Amazon at $9 ‐‐ maybe less but I didn't look too hard