Soft brake pedal, can pump up but fades
#1
10-06-2018, 01:02 AM
Soft brake pedal, can pump up but fades
2000 Disco II. 91k miles.
Soft brake pedal with engine running, I can pump it up but it fades about 2 inches. The pedal is hard with the engine shut off.
I have done a fair amount of automotive work over the years but I'm not up on the newer stuff with ABS.
I thought the master cylinder was leaking internally so I replaced it. After some struggling with bleeding by myself I have gotten the brakes back to feeling like they did before I replaced the MC, maybe slightly worse but certainly no better. I used the ABS pump to bleed. I also bled the lines at the ABS, I didn't see any air. I have to confess that I bled the lines at the ABS after bleeding at the calipers.
It doesn't make sense to me that the booster would cause this symptom, or air in the lines. I'm running out of ideas and getting frustrated. Dumping it in the river has crossed my mind.
I have searched forums quite a bit and I see replies about rubber brake lines causing a soft pedal and being able to pump the pedal to make it firm, but I don't think the pedal would then fade if that were the cause, please let me know if I'm wrong.
Just to give some history, I recently also replaced the rotors and pads, then parked the rig for about 6 weeks. I didn't a constant 3 amigos driving around the driveway at that time. Last weekend I bench bled the MC and put it on. Today I bled the system, now I have the 3 amigos and they won't go away.
I had been getting the 3 amigos intermittently, turning off the engine and pushing hard on the brake pedal would generally clear it.
I didn't do anything with the ABS sensors while I had the rotors off, maybe I should have cleaned them?
I bought an ABS Amigo, but I haven't gotten it yet so no codes available at this time.
Also, about a year ago I bled the brakes with help, using the pedal. I managed to get a nice firm pedal but in 2 or 3 days it returned to the way it had been.
Any help on either the soft pedal or the 3 Amigos would be appreciated.
Soft brake pedal with engine running, I can pump it up but it fades about 2 inches. The pedal is hard with the engine shut off.
I have done a fair amount of automotive work over the years but I'm not up on the newer stuff with ABS.
I thought the master cylinder was leaking internally so I replaced it. After some struggling with bleeding by myself I have gotten the brakes back to feeling like they did before I replaced the MC, maybe slightly worse but certainly no better. I used the ABS pump to bleed. I also bled the lines at the ABS, I didn't see any air. I have to confess that I bled the lines at the ABS after bleeding at the calipers.
It doesn't make sense to me that the booster would cause this symptom, or air in the lines. I'm running out of ideas and getting frustrated. Dumping it in the river has crossed my mind.
I have searched forums quite a bit and I see replies about rubber brake lines causing a soft pedal and being able to pump the pedal to make it firm, but I don't think the pedal would then fade if that were the cause, please let me know if I'm wrong.
Just to give some history, I recently also replaced the rotors and pads, then parked the rig for about 6 weeks. I didn't a constant 3 amigos driving around the driveway at that time. Last weekend I bench bled the MC and put it on. Today I bled the system, now I have the 3 amigos and they won't go away.
I had been getting the 3 amigos intermittently, turning off the engine and pushing hard on the brake pedal would generally clear it.
I didn't do anything with the ABS sensors while I had the rotors off, maybe I should have cleaned them?
I bought an ABS Amigo, but I haven't gotten it yet so no codes available at this time.
Also, about a year ago I bled the brakes with help, using the pedal. I managed to get a nice firm pedal but in 2 or 3 days it returned to the way it had been.
Any help on either the soft pedal or the 3 Amigos would be appreciated.
Last edited by Sub-arctic Rover; 10-06-2018 at 08:57 AM. Reason: adding info
#2
10-06-2018, 09:38 AM
Super Moderator
Get 15ft of say 16 gauge wire, a toggle switch or push button style switch, open the hood, remove the ABS relay and insert your two wire leads into the front/rear slots, then crawl under the D2, flip the switch ABS pump will run, open bleeder, close the bleeder when you see either new fresh fluid or a steady stream of brake fluid. Shut the bleeder, toggle the switch off, top off the reservoir, and go to the next wheel.
That way you can do a power bleed without any $$$ diagnostic tools. Also for kicks make sure all your upper 6 intake manifold bolts are tight because you can have a vacuum leak = soft pedal.
That way you can do a power bleed without any $$$ diagnostic tools. Also for kicks make sure all your upper 6 intake manifold bolts are tight because you can have a vacuum leak = soft pedal.
#4
10-06-2018, 05:37 PM
Super Moderator
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