I'll give the full back story to this in order to try avoid wasting anyone's time with follow up questions.
1998 Discovery 1, with ABS.
The initiation of the issue was after I installed new rear rotors and pads. Once everything was back together I couldn't get the calipers to bleed. I tried both the two man bleed method and a MityVac hand pump, both to know success. I ended up buying a pressure bleeder so that I could stop calling my wife to the garage to push on the brake pedal. However, despite that building pressure, no fluid came through to the calipers, even the front ones. I finally tracked the issue to the master cylinder. The pedal bleeding had pushed old corrosion to the point of blocking the outlet and no fluid was getting out of the master cylinder.
So, I replaced the master cylinder with one from Atlantic British. From there the system bled normally (pressure bleeder) and I was able to get pressure back. However, upon driving the car the first time, the brakes became spongy. I checked for leaks and found oil on the passenger rear rotor. I tracked that down to a blown stub axle seal, but replaced the caliper pistons and seals for good measure, along with new pads. Then I bled the system again for good measure. Again, when I drove the car the brakes became spongy again. I drove it this way for a few months, just occasionally for local errands, as I didn't have time to further troubleshoot. Although the brakes didn't inspire confidence they were still functional.
Then a few weeks ago, I found a leak at the driver's front caliper. This was clearly from caliper the pistons and seals and so I replaced them, along with new pads. Again, I bled the entire system at each caliper. The pedal felt solid as a rock. However, as soon as I drove, it became spongy again. So, I spent today doing some additional testing.
1) Inspected for leaks at all hoses and calipers. Found none and fluid level in reservoir is not changing.
2) Inspected seals where the reservoir meets the master cylinder (even though they're less than a year old). No leaks
3) Sprayed the reservoir cap with soapy water to check for air leaks there, but nothing.
4) Checked the hose from the brake servo to engine for vacuum retention, on the engine side, all good.
5) Rebled the system and found no air in it.
Current Symptoms:
Pedal is solid with the engine off
Pumping the pedal doesn't increase it's firmness
With the engine on, applied pressure will result in the pedal gradually going the floor (over the course of a minute or more)
Any suggestions on where to look from there? Thanks in advance for the help.
1998 Discovery 1, with ABS.
The initiation of the issue was after I installed new rear rotors and pads. Once everything was back together I couldn't get the calipers to bleed. I tried both the two man bleed method and a MityVac hand pump, both to know success. I ended up buying a pressure bleeder so that I could stop calling my wife to the garage to push on the brake pedal. However, despite that building pressure, no fluid came through to the calipers, even the front ones. I finally tracked the issue to the master cylinder. The pedal bleeding had pushed old corrosion to the point of blocking the outlet and no fluid was getting out of the master cylinder.
So, I replaced the master cylinder with one from Atlantic British. From there the system bled normally (pressure bleeder) and I was able to get pressure back. However, upon driving the car the first time, the brakes became spongy. I checked for leaks and found oil on the passenger rear rotor. I tracked that down to a blown stub axle seal, but replaced the caliper pistons and seals for good measure, along with new pads. Then I bled the system again for good measure. Again, when I drove the car the brakes became spongy again. I drove it this way for a few months, just occasionally for local errands, as I didn't have time to further troubleshoot. Although the brakes didn't inspire confidence they were still functional.
Then a few weeks ago, I found a leak at the driver's front caliper. This was clearly from caliper the pistons and seals and so I replaced them, along with new pads. Again, I bled the entire system at each caliper. The pedal felt solid as a rock. However, as soon as I drove, it became spongy again. So, I spent today doing some additional testing.
1) Inspected for leaks at all hoses and calipers. Found none and fluid level in reservoir is not changing.
2) Inspected seals where the reservoir meets the master cylinder (even though they're less than a year old). No leaks
3) Sprayed the reservoir cap with soapy water to check for air leaks there, but nothing.
4) Checked the hose from the brake servo to engine for vacuum retention, on the engine side, all good.
5) Rebled the system and found no air in it.
Current Symptoms:
Pedal is solid with the engine off
Pumping the pedal doesn't increase it's firmness
With the engine on, applied pressure will result in the pedal gradually going the floor (over the course of a minute or more)
Any suggestions on where to look from there? Thanks in advance for the help.