94 brakes are still spongy.

Pablo94SC

Registered User
I'm running out of ideas here guys. My brakes still are spongy despite replacing the brake lines, the front calipers, all pads and rotors, the master cylinder, and bleeding the system numerous times using the ABS break-out tool. Even swapped an old, known good check valve in the booster without helping things. Car has no vacuum leaks.

Booster has been replaced once before when I had similar issues, but it turned out to be a bad MC. Any suggestions before I go out and replace the booster? Anyway to fully bleed the ABS system besides the tedious process of using the break-out box?

Thanks guys.
 
Adding the procedure for people looking for it. Might save some searches.

With Antilock Brakes
The master cylinder and hydraulic control unit must be bled using ABS test adapter T90P-50-ALA. If this procedure is not followed, air will be trapped in the hydraulic control unit which will eventually lead to a spongy brake pedal.

To bleed the master cylinder and HCU, disconnect the 55-pin plug from the ABS module and install the ABS test adapter to the wire harness 55-pin plug.

1. Place bleed/harness switch in bleed position.
2. Turn ignition to ON position. At this point the red OFF indicator should turn on.
3. Push motor button on adapter down to start pump motor. The red OFF indicator should turn off and the green ON indicator should turn on.
4. Pump motor will run for 60 seconds once motor button is pushed. If pump motor must be stopped before 60 seconds, press abort button to turn motor off.
5. After 20 seconds of pump motor operation, push and hold valve button down for 20 seconds then release.


Brake lines may be bled in the conventional manner. Ensure lines are bled in the following sequence:

1. Right Rear.
2. Left Front.
3. Left Rear.
4. Right Front.
 
make sure you dont have any caliper sliders or pistons that are frozen. I've seen that kind of problem cause a soft pedal. I realize you have replaced the front calipers. Only other things I can think of is a bad master cylinder or the modulator valve for the abs is bad. This just happened one day I assume right? Didn't occur after doing brake work or anything? I'm not an expert on brakes but I thought a bad booster would cause a hard brake pedal not soft. Vaccum leak would surely cause a hard brake pedal.
 
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make sure that the bleeder valve on the caliper is at the top i have see guys put right on the left, it all bolts up and you never get the air out. another way to try and narrow it down is do a line clamp test. start clamping the brake lines and see if the pedel gets more firm.
 
My Brother was working on an old Chrysler and after replacing the brake calipers he had one heck of a time bleeding the brakes. Eventually he cracked the bolt to remove the caliber brake line a bubble of air burped out that was trapped in the brake line connection. He owned a brake shop and had all the expensive equipment to bleed brakes and after a couple of days of trying to fix the spongy brakes concluded that one of the calibers were bad. After the air burp the brakes were very firm. It was hard for me to believe that a tiny air bubble could make the brakes feel so bad.

Mark
 
Took the car to a shop today to have the brakes pressure bled. Looks like the PS front brake line has some sort of blockage in it as the fluid barely trickled out of the bleed screw... even when it was out of the caliper. :( Going to check the hard lines for damage and then start with the caliper and work my way back, connection by connection, to the ABS unit until I find the restriction. *sigh*
 
I have the tool but where do you plug the t90p-50-ala brake harness too?

n/m found it. :)

Cheers,
Luke
 
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Still weak after all this time and a MC change. Taking it to a shop today to finally get it all sorted out.

For those that are wondering what I'm experiencing... it's like I have normal braking power, say one-third pedal, from there to the floor. Like you would use gradually slowing down while in your neighborhood. If I had to panic stop, I'd be toast.

edit: there is no longer a pull to the left and the right front caliper, which barely bled, is bleeding fine now.
 
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