1993 Atx brake HELP!!!!!

[randy'sho]

Ok I have racked my brain reading post after post, going to the garage and trying everything that I have read and STILL having the same problem....

Here it goes

93 Atx purchased with very soft brake pedal.....can pump up once or twice with car off and pedal hold firm.....start the car and pedal sinks to the floor....STOP, when I bought the car it had been sitting for almost a year, because the owner lost his job and couldn't pay to have car registered.....btw the mc reservoir was dry......filled it up and bleed brakes with no luck

Had to replace rear soft brake line because it had collapsed....no leaks in brakes anywhere.....put car on jack stands in garage and inspected entire system with no visible issues sighted.

Did a few more tests and reading and came to the conclusion that my master cylinder had to be bad....ordered a new mc, bench bleed as best I could, installed on car, filled fluid and bleed the crap out of all 4 wheels in correct sequence.....NO CHANGE at all.....

With car started, pedal sinks to floor barely stopping car....I can pump the pedal 3-4 times and get it to grab decently, but when I let off pedal and go to stop again, it sinks down the same way.

I drove down a gravel road and smashed the brakes and the abs does kick on

Someone PLEASE give me some sound advice before I push it in the weeds!

Car runs great....checked all vacuum lines to booster and all is well, no leaks from booster of any kind

 

[sperold]

That is a real puzzle.

Without knowing anything specific about the brake system on the SHO, my guess would be there is still air in the lines. That crazy bundle around the ABS controller under the hood seems like a good place for air to get trapped.

Although you have already done it, I would bleed the brakes again the way you are doing it and I would consider getting a "one-man bleeding system" if the conventional way doesn't work.

 

[randy'sho]

I'm bleeding with car running....that is correct right....looked at the manual this evening and it actually says nothing about having the car running, but that is always the way I have bleed on other cars

 

[SHOdded]

Bad master cylinder? Which one did you buy? Also, look into replacing booster as it will be compromised by a leaky master cylinder.
http://www.shoforum.com/showthread.php?t=128346
http://www.shoforum.com/showthread.php?t=125978

 

[rubydist]

before you spend any more money, get the brakes bled. the abs system on these requires special equipment to bleed properly, and I am willing to bet that your issue is that there is still air in the system.

 

[randy'sho]

before you spend any more money, get the brakes bled. the abs system on these requires special equipment to bleed properly, and I am willing to bet that your issue is that there is still air in the system.

Should I just bleed the conventions way? Have the car running and start at rear passenger and work my way up?

 

[sperold]

I don't think it is mandatory to have the car running.
I would get information on what you need to do the special bleed Rubydist is referring to. I think that there is pressure involved (other than the master cylinder supplied pressure) that forces the air out of the various local high points in your system. But, like I said, I don't have any specific info on the SHO system.

 

[randy'sho]

Gonna try gravel road to make sure all air is out of abs and then bleed again

 

[220ksho]

How does the pedal feel while driving w/o boost? Does the car stop? Pedal stay firm?

 

[Fordlover96]

I had the exact same problem a week ago. Got in the car one day and the pedal just went to the floor. Yet, with the car off the pedal was firm but with the car on it went to floor. I changed out the MC and the stops better than ever. Did you make sure that all the bleeder screws were tight and the connection to the MC were tight?

 

[SHOMON]

I think the bleed sequence starts w the left front wheel. Then RR, LR, RF.

 

[randy'sho]

Checked it all out thoroughly.....went for a gravel road drive yesterday.....did 4-5 abs stops.....pedal sinks on first push and gets firm after a few pumps! Sure seems like air in line somewhere! Need to bleed again now!

 

[Irish Pride]

i think the bleed sequence starts w the left front wheel. Then rr, lr, rf.

rr, rl, fr, fl.

 

[randy'sho]

rr, rl, fr, fl.

Yep....start from furthest away

 

[SHOMON]

The Taurus and Sable brakes are diagonally linked. We use Mitch On demand at work. I will double check the sequence tomorrow. Chiltons says RR, LF, LR, RF

 

[SHOMON]

Just checked Mitch on demand. The sequence is RR, LF, LR, RF.

 

[randy'sho]

I have tried everything....manual bleeding....gravity bleeding....gravel road technique......still have to pump pedal at least once or twice to get a good brake.....brakes on right side seem to work best. Noticed also that when pumping the brakes that the motor stumbles I'm guess from using vacuum

 

[sperold]

Here is something that may help. The article states that high pressure brake fluid is stored / trapped in an ABS accumulator and rather than have the car running, you remove the battery. So that is a new one for me, so it sounds complicated.
Sounds like you need some "sophisticated machinery" like Rubydist mentioned for a successful bleed. I would look into that.
Hope this info helps.
http://www.wikisho.com/wiki/Brake_System_Bleeding
Good luck!

 

[TheVancen]

I'm having this exact problem, did you get it all sorted out? I'm going to try bleeding it again tomorrow, the correct way this time.

My only worry is one of the brake lines I made, (tight budget, what can you do), goes further upnthe fire wall than the original. Which I believe goes under the pinch weld seam near the top of the firewall?

In case my home made line is part of the problem, is there a specific way to get to the line? It's the main hard-line for the right front. At some point, the car has also had the little block on the inside of the left front wheel well deleted, is that a problem.

The boys of owning a neglected $400 car, am I right?