My brakes went out a while ago, so I replaced the master cylinder. Bench bled it, bled the whole system and drained out all the old fluid. The car stopped wonderfully... for a while. I had the E-brake on one day, released it and went for a drive. For some reason, the pedal was spongy.
So, I bled the brakes again, getting very little air. After that, it was fine. Until today. I had the E-brake on again, released it and the spongy pedal is back. It's not gradual loss of pedal, either; it was fine ten minutes earlier. So I pop open the MC, and the rear reservoir is down a little from where it should be. I filled it up and it's still spongy.

So, before I bleed it all again, does anyone have any suggestions as to why it seems that using the E-brake is making my pedal spongy? It doesn't make any sense to me. Is it sticking? Do I have a leak somewhere? I can't find a one, but that fluid has be going SOMEPLACE. What should I check next?

Anyways, thanks in advance
:D
- Ryan

Originally posted by PearlBlack71:
The car stopped wonderfully... for a while. I had the E-brake on one day, released it and went for a drive. For some reason, the pedal was spongy.
So, I bled the brakes again, getting very little air. After that, it was fine. Until today. I had the E-brake on again, released it and the spongy pedal is back. It's not gradual loss of pedal, either; it was fine ten minutes earlier. So I pop open the MC, and the rear reservoir is down a little from where it should be. I filled it up and it's still spongy.

:D
- Ryan Your losing fluid somewhere between the master and the rear wheel cylinders.Wherever fluid leaks out no matter how minute air can get in.
Even though its a new M/C its possible that its leaking out the rear seal of the M/C.Pull the 2 nuts that hold it to the booster and look for fluid if its wet bring the m/c back and get a new one.
Using the parking brake pushes the front shoe out against the drum relaxing return spring tension on the wheel cylinder.This can allow fluid to leak out or air to get in at this point.Check for fluid at the w/c boots,you may have to use a small screwdriver to pull the boot off to inspect them.
The last thing to check would be the rubber and metal lines.Brake lines with thick rust can also hide pinhole leak locations.
The most likely cause would be the rear wheel cylinders.

Using the parking brake pushes the front shoe out against the drum relaxing return spring tension on the wheel cylinder.This can allow fluid to leak out or air to get in at this point.Check for fluid at the w/c boots,you may have to use a small screwdriver to pull the boot off to inspect them.
The last thing to check would be the rubber and metal lines.Brake lines with thick rust can also hide pinhole leak locations.
The most likely cause would be the rear wheel cylinders. [/QB]Thanks, John. I am going to check the wheel cylinders later if I have time (finals week). All the brake lines are new and unrusted, so I don't think they would be the problem. I am also inclined to think that it is the rear wheel cylinder...
I'll post an update when/if I find the problem.
Thanks again! graemlins/thumbsup.gif
- Ryan

It's been a while since I posted about my brake problem, but I thought I would post an update since it might be helpful to someone else someday.

I pulled off all the wheels, checked for leaks around the brakes themselves and found none. My rubber lines didn't look too good, so I replaced them with some Earl's flexible stainless lines. I did, however, find two leaks in the brake system, one on the metering block and one at the back where the hard line goes to the flex line for the rears. After tightening everything up, replacing the brake lines and bleeding the system again my brakes are back to normal and no fluid is "mysteriously" disappearing... The pedal even feels a little better with the stainless lines.

I couldn't see where it was leaking at the block or at the back until I jacked it way up and got underneath.

So, anyways, problem solved, happy ending.
graemlins/thumbsup.gif

- Ryan