Topic: Did I ruin my master cylinder?

[IVrunner]

I just finished doing a small project on the front end of my stock 87 4runner 22re:  new rotors, new wheel bearings, auto hub to manual conversion, new pads.  My problem happened when I buttoned everything up.  I was putting in the last brake pad and all of the sudden brake fluid started pouring out on to the ground from near the MC.  I obviously had to push back the cylinders in the caliper to fit the new pads in, but evidently doing that pushed out a bunch of the fluid out the top of the reservoir.  I didn't think too much into it.  i just assumed it was a little too full once i put all the new pads in.  However i then went to check the brakes and they went to the floor.   I tried to bleed the brakes, but it wouldn't build pressure at all.  The more I bled them the worse the brakes got.

Did I cause the MC to fail when the pressure popped fluid out the reservoir or does MC simply need re-bench bled??

[crazykooter]

Bleed the master cylinder.  There is a bleeder which most never use.  If yours doesnt have one then bleed it using the fittings on the master.  That should solve ur problem.  You just got air in the lower part of master.

[jrock]

What Crazy said. I had just about the same things happen.

[crazykooter]

What Crazy said. I had just about the same things happen.

Ya but I think you put beer in your master.   

[IVrunner [OP]]

That's good to hear, thanks.  Even though I kind of wanted an excuse to upgrade the MC.   So, I guess I'll keep this one for now (it is only a little over a year old) Question - Can I bleed it installed or do i need to take it off and bench bleed it?  I didn't see anything in the FSM and the haynes really only talks about bench bleeding from what I can tell.  Although there is one diagram that pretty much says you can pump the pedal and hold then loosen each fitting nut on the MC until fluid is clear of air bubbles.  Am I understanding this correctly?  Is this what others would recommend?

[crazykooter]

Dont bother removing the master.  It really doesnt help bleeding it.  Tho bleeding a master cylinder does require 2 people.  When you crack the hard lines have someone press the peddle down slowly.   Bleeding the master isnt hard just make sure the guy whos pressing the peddle is very smooth.  Any little glitch pushing the peddle down will suck air fast.
Hope this makes some sense.  I am dead tired and heading off to bed. 

[Rocksurfer]

Eh wouldn't worry about it, when you compressed the calipers you forced the fluid that was in the caliper back into the reservoir. Didn't hurt a thing except for the paint on the firewall. I usually suck out the the reservoir with a turkey baster before I compress the calipers, that is unless I forget and then I end up with the same mess on the floor.

[IVrunner [OP]]

I am still at a loss with this.  I have bled the system multiple times using multiple methods and I am still left with brake pedal that goes to the floor.  

I have checked the booster by creating pressure and then starting and also by pulling the vacuum hose after shutting off.  Both of which resulted in a good booster. 

I have also checked the master by buying a piece of 8" hard brake line, cutting in half, crimping each end and attaching to the master cylinder in place of the lines to the front and rear.  With the line closed off I pushed the brakes and they were as hard as a rock, so this means my plunger and all the internals are OK.

I have bled the system the following ways with the same result:
- bled at each wheel using both a vacuum pump and a helper pumping in the cab
- bled running, not running but ignition on, and not on at all
- bled in different sequence: furthest to closest, closest to furthest

The vacuum pump method seemed to pull out air the whole time no matter how many times I did it.  The only thing I could think of is that it was creating air as it was pulling the fluid out, but not sure.

The pedal pump method seemed to squirt out fluid only at each wheel, but what was weird is that it seemed to have less and less pressure each time.  Same thing once you moved to the next wheel.  One part that made this difficult is that the pedal goes to the floor as you pump it, so by the time you crack the bleeder it barely has room to go down.

I really have no idea what to do next besides checking every fitting.  A friend has said that I could gravity bleed it, so I might try this as well. I'll try anything at this point cause i'm stumped.

[OOPS]

Is this how you are bleeding hem?

"...This is from the FSM and it works great..."
1. Drivers side rear
2. Passenger side rear
3. Passenger side front
4. Drivers side front
5. LSPV (Load sensing proportioning valve)

[IVrunner [OP]]

I did do it that way, but also did the opposite just in case since the vacuum bleed kit says to do it this way   I already had the kit to check for vacuum problems on an old accord I had.  Bleeding the LSPV is news to me so I did not do this.  That makes me think this is the problem.  How do I do it?  I don't see a bleeder on the component layout.

[OOPS]

All of them that I have worked on have had a bleeder just like the calipers and wheel cylinders.

[IVrunner [OP]]

I had never realized there was one - I did look in the morning and sure enough its there.  Hopefully thats where the problem lies - thanks.

[yota4x4sc]

next time crack the bleeder while u push the piston back in!!!!!

[IVrunner [OP]]

yota4x4, I heard that was only ever crucial when you have ABS.  I meant to take some fluid out before pushing the piston back in.

I re-bled per the FSM and still very little peddle. 

I heard from a friend that you can pinch off each rubber flex hose to figure out which section has the problem.  If you get a hard peddle once you pinch off a hose the problem is there.  Has anyone ever done this?  I feel like doing so will risk messing up the flex hose.

[crazykooter]

Ya you can pinch off the rubber lines to see where the problem is.   I am starting to think your master took a dump on ya bud.  With all the bleeding you have done it should have worked.  You might have ripped the plungers rubber seal.  Very rare but it can happen.  If you remove the master and look at where the rod goes into the housing, there is a c clip there.  Remove that and pull the plunger out.  You will be able to see the seals I am talking bout.  Its really easy.  If you need any help you can call me.  I can walk you thru it all.  I cant remember peoples names or where I have been for the last day but I can rebuild a toyota in my head.  How messed is that. 

[yota4x4sc]

u should try to bleed ur proportioning vaulve.. most ppl always forget to bleed them..and i would not  reccomend pinching ur brake lines

[IVrunner [OP]]

i bled the proportioning valve the last go around.  Basically i re-bled per the 5 locations in correct sequence...each location 2 to 3 times.  Every spot looked good (no bubbles) but there was barely any pressure.  I will continue by taking the master off and checking the seals.

Thanks for all the input, guys.  If I get stuck i'll call you, crazykooter

[yota4x4sc]

 i don't know if u tried, but they make a vacumn sucker thing u hook to a air line and those work really good for getting all the air out the entire system.. u might wanna give it a try if u can get a hold of one