New Brake Booster, MC and lines were bleed, but brakes still feel soft or spongy.

[Xylene]

I have a 1998 Explorer V8 AWD. I replaced the Brake Booster and the Master Cylinder today. I bleed the MC before putting it on according to the instructions that came with it. I also bleed each brake cylinder starting with RR, RL, FR, FL until fluid was clear and there were no air bubbles. I added additional fluid to the MC reservoir as needed so it never was low. (actually went through 76oz of fluid)

After all this my brakes still fill soft or spongy when the car is running, but when not running they firm right up after pressing the pedal a couple of times. I was kind of expecting the pedal to always be firm when I used them.

What did I do wrong in my procedure, what could be causing this soft feeling in the pedal? I didn't bleed the ABS unit because I didn't have the fancy FORD tool, so I guess that could be it.

Anyone else have this issue?

 

[koda2000]

Did you replace the rubber brake lines? When they get old they expand when the brakes are applied and give a spongy feel. Also it is very hard to bleed air out of a ABS system. You may need to take it to a shop with the equipment to do it properly.

 

[Xylene]

Did you replace the rubber brake lines? When they get old they expand when the brakes are applied and give a spongy feel. Also it is very hard to bleed air out of a ABS system. You may need to take it to a shop with the equipment to do it properly.

I didn't see any noticeable expansion in the brake lines, but if I cannot figure out what is going on that might be the next thing I replace.

I plan on contacting the dealership on Tuesday to find out what they will charge to bleed the ABS system for me.

 

[koda2000]

I didn't see any noticeable expansion in the brake lines, but if I cannot figure out what is going on that might be the next thing I replace.

I plan on contacting the dealership on Tuesday to find out what they will charge to bleed the ABS system for me.

If you still have your original 1998 rubber lines, the should be replaced. I doubt you'd notice them expanding visually. The reason the pedal feels hard without the engine running is because you use up the stored vacuum assist after a couple of pumps. Any qualified shop should have the equipment to bleed ABS brakes, you don't need to go to the Ford dealership.

 

[jrgaylor]

You still have air in the system, getting all the air out can be a real pain. I spent about 5 hours getting my brakes to work correctly after swapping in my new axles and that was on a rig without the ABS which is likely where your problem is.

 

[lobo411]

IIRC, I paid $40 to have a brake shop bleed the ABS system when I replaced my master cylinder. Took them 15 mins.

 

[Harper]

I agree with both above assessments it could be one or the other or both. A good brake shop can save you a lot of head aches. Good luck

 

[SoNic67]

I have a similar issue in my 2002 Sable, but maybe different. New break pads, changed the MC, bleed the system (flushed a whole 32oz bottle), including the ABS using the Forscan software.
When engine is running (boosting the brake force), if I press the pedal it goes to a point where it kind of stops. But if I press really harder after that, the pedal will sink slowly to the floor.

I suspect that either the hoses swell under that high pressure or... one of the caliper pins is bent and the high pressure "straighten" it enough so that the cylinder travels more.
I will take apart the brakes in a while and see if there is any asymmetrical wear on the new pads that would point to pins. If not, I might need new brake hoses.

 

[jrgaylor]

I have a similar issue in my 2002 Sable, but maybe different. New break pads, changed the MC, bleed the system (flushed a whole 32oz bottle), including the ABS using the Forscan software.
When engine is running (boosting the brake force), if I press the pedal it goes to a point where it kind of stops. But if I press really harder after that, the pedal will sink slowly to the floor.

I suspect that either the hoses swell under that high pressure or... one of the caliper pins is bent and the high pressure "straighten" it enough so that the cylinder travels more.
I will take apart the brakes in a while and see if there is any asymmetrical wear on the new pads that would point to pins. If not, I might need new brake hoses.

From my experience I think you still have some air in the system

 

[Xylene]

OK so here is a strange thing. Today was a lot warmer than the day I changed out the MC and brake booster, and the pedal felt pretty good. Probably better then it has felt in a long time. Could the temperature affect the braking system, or was it something else?

 

[koda2000]

Outside temp has no effect on brake fluid or the brake system. Perhaps letting it sit awhile allowed some of the air bubbles to escape from the ABS system... ?