Squishy Brake Pedal...TURTCEL

[TURTCEL]

So I had to replace my master cylinder do to it leaking from the backside into the booster area...it worked fine still though, just lost a little fluid. The only part I could get in stock was a reman so I put it on and bled the brakes.

I started at the right rear...all ok, then the left rear...almost nothing and lost all pedal pressure. The fronts didn't want to bleed well either. Figured it was a bad master so I warrantied it out. Replaced it and had the same issues. Any thoughts on why I can't get the system to bleed now? Fluid flows from all corners but not like it should.

Peace

[dlb]

did you bench bleed the master cylinder before putting it in?

[marlinh]

Also, when you install the master, it helps to bleed the system right at the fittings. Have someone slowly press the pedal, open the fittings one at a time. Close them when the pedal reaches the floor. If you get any bubbles repeat.

You should be able to pump the brakes up, do it slowly until the pedal comes up. Then start bleeding the system again. Good luck.

[larry mcgrath]

John the master cyl needs to be bench blead like dbl stated above.remove the cyl put it in a vice, put some cutoff brake lines from the ports back into the resivor and slowely pump the plunger,this will remove the air that is in the master cyl.If you dont do this you won't be able to properly blead the breaks ,no mater how much you try.If you have trouble give me a call you should have my number. Larry

[TURTCEL]

I bench bled the master cylinder in a vice before install, bled it at the master cylinder lines, used a vacuum bleeder, used a master cylinder pressure bleeder, and pedal pump bled the system. TWICE NOW. I am totally stumped as well as my dad who is an auto mechanic for the City of Seattle. We have been working on it together.

I am not getting any action in the master when we depress the pedal with the cap off so we thinking we have gotten 2 bad master cylinders. We can hear the master making noise when the pedal is depressed but sounds more like a squishing noise.

I am going to order a new one from RockAuto today and hopefully that will solve the problem.

Is the junction block on the cars for the brake lines an actual proportioning valve or just a directional block? Could it be bad? Does the master cylinder control the brakes with 2 resivores one for the fronts and one for the rears or are they in a cross pattern controlling the RR and LF and the other controlling the LR and RF? It seems to have good bleeding ability at the RR but not as good the rest of the wheels.

Peace

[marlinh]

I think they work in a crosswise direction. If one side fails you have brakes one front and opposite rear. That's what I seem to remember.

Sounds like you guys are both knowledgeable. Maybe these masters have been sitting on a shelf too long and they are both bad. That would be my thoughts after what you both have gone through.

One chamber of the master controls the front and the other the rear. If I guess which one, I am sure to be wrong.

Just curious, what does the pedal feel like? Right to the floor, spongy?

[TURTCEL]

So the pedal never got better than a little spongy. It would feel like there was a little pressure and the brakes definitely were working to a point when we checked. One of us would hold the brake while the other would check each corner for brake action and they all seemed to be working but not with a strong pressured pedal. Pedal would never pump up fully and sometimes would not have any activity at all while bleeding.

One odd thing I noticed was that when the car is not running the pedal feels like there is pressure there but once the car is running and the booster is active the pedal completely goes away and there is no brake function at all.

I ordered a new master from RockAuto today and it should be here in a week so my friend is lending me his little pickup for the work week till my new part comes.

This is totally a draining experience and a PITA. Hope the new master will fix the problem.

Peace

[marlinh]

Are you saying that the pedal went to the floor after you start the car? And there was no brake application while it was running? That is really weird!

[TURTCEL]

Yep, that's right. When car is not running the pedal will pump up to a point and have some pressure. But as soon as I start the car the pedal goes to the floor when I depress it with no resistance and no brake....veru weird. No leaks anywhere either.

TWIGHLIGHT ZONE

Peace

[c_j]

Is the junction block on the cars for the brake lines an actual proportioning valve or just a directional block? Could it be bad? Does the master cylinder control the brakes with 2 resivores one for the fronts and one for the rears or are they in a cross pattern controlling the RR and LF and the other controlling the LR and RF? It seems to have good bleeding ability at the RR but not as good the rest of the wheels.

A long time ago, I had that proportioning valve stick on me when I was bleeding large amounts of fluid. If I remember correctly, I was able to push something in one of the brake line holes on that block and unstick it. I think I used a piece of steel welding rod or something similar. I may have even had to tap it loose with a light hammer. I think it should feel springy when you push in there as opposed to solid.

In my case, I think I was getting no fluid at one wheel and I traced the line to that block. Then I looked at the body of that block and you can see by the way it is shaped that there is a channel running top to bottom (I think?). Then I undid the line at the end of that channel. When I poked something in there, you could tell it was blocked off by something (a piston), and after I tapped it free, you could push in further and feel the springy action of the piston.

It shouldn't be getting stuck, but that is what happened when I tried to bleed too fast (pumping pedal method). Maybe a piece of debris got lodged in there or something.

proportioning_valve.JPG

If we number those lines from left to right, then:

1. to rear of master cylinder
2. to driver-side front wheel
3. passenger-side rear wheel
4. driver-side rear wheel
5. to tee, branching to front of master cylinder and also to passenger-side front wheel

You can tell that #1 and #2 are just teed together in the casting, so that means that each part of the master cylinder runs each front brake separately. Also each of those lines is crossed to the opposite rear brake within that valve.

[TURTCEL]

Thanks c_j, that was my next area to check. I am going to do a brake line back flush with the master cylinder disconnected to see if anything is clogging the line or the proportioning valve. I am just a little leary of breaking the lines loose at the prop valve just in case anything goes wrong a repair to a line would be a PITA.

Peace

[Petros]

I know some people that always replace the proportioning valve with a new one when they replace the master (I think as a preventative measure). I have never had one go bad, once I had one stuck, but I found if I stomp down on the pedal it re-centered itself (an old chevy truck).

I think your problem is just air still in your system. if the system gets air in it, or if starting from a completely empty system, it takes a lot, a lot, a lot of pedal pumping and bleeding the brakes to get all of the air out. It is also possible you have some bad rear wheel cylinders, did you check those? if bad enough they can allow air back into the system.

[TURTCEL]

Wheel cylinders were dry and functioned. We pulled back the dust boot to make sure they were not leaking inside either.

The funny thing is I only changed the master because it leaked but the brake system worked totally fine. Now after changing the master there is almost nothing there. We definitely have bled the lines and I didn't start with an empty system. I had recently (6 months ago) completely flushed the system and had no issues then.

I can't seem to get hardly anything out of the left rear or right front. But I bleed the right rear just fine. It will make the pedal stiffen up but once I start with the left rear everything goes away. Something is wrong with this picture and it is definitely not just air in the line. I am going to do a complete back flush to see if there is something blocking the lines. Should I remove and clean the proportioning valve or just back flush through it to see if it is also clogged?

I did stomp the pedal hard many times, but there is no "pedal pressure" to stomp.

New master comes today...I will keep you all posted.

Good to hear from you Peter, it's been a while. OT...did you get the 4AC in and running?

Peace

[Petros]

Good to hear from you Peter, it's been a while. OT...did you get the 4AC in and running?

Yes, running strong with new clutch. Now I need to get after one front wheel bearing...

I am having brake issues right now with the Tercel4wd that I am supposed to be driving home today. lots of airbubbles trying to bleed the new wheel cylinders...I am putting in a new master today.

[TURTCEL]

Problem solved...the new master cylinder took care of the problem. looks like Petros and I had the same results.

Good to have the Terc back. Next step...WEBER carb swap.

I highly recommend not buying any reman brake parts for these cars, especially A1 Cardone. Between Petros and me we have come across 3 reman Cardones in a week that were bad off the shelf. I will be returning mine tomorrow for a refund.

Peace