Squishy brakes

Achias · 10-09-2011, 10:43 PM

Ilsa's giving me a bit of a run today. Her brake fluid was getting dark, so I replaced it. While bleeding the brakes, I let the fluid in the master cylinder get too low, and had to start all over again. Luckily, I'm using a power bleeder so it goes a little faster than the manual method. I thought I had all of the air out of the lines, but the pedal is still very soft. I'll try again tomorrow.

Achias · 10-10-2011, 08:33 PM

Hmm - I bled the lines again and they're still not tight. Am I missing anything?

Achias · 10-13-2011, 03:23 PM

OK, help me out here, please.

I just finished bleeding Ilsa's brakes for the third time. This time, I ran an entire large bottle of DOT3 through using the power bleeder. When the engine is off, the pedal is rock solid. With the engine on, the brakes work fine; but after I'm stopped, I can gradually push the pedal all the way to the floor.

Is this normal?

CQQL_SSR · 10-13-2011, 04:09 PM

If there is no visible brake fluid leak and the fluid in the resevoir is not going down then it could be a bad master cylinder.
The fluid would be leaking back past the piston when under pressure with the power assist.
I have not read any posts about this happening to an SSR master cylinder.

Antique · 10-13-2011, 06:40 PM

It seems odd that it started after you changed the fluid. Anything is possible but I'm betting on the bleeding. The old school is to have someone pump it up and hold very solid pressure with a second person holds a rubber tube from the bleeder into a jar with a little brake fluid in it with the hose in the fluid so air cannot get back in when you repump the brakes. then slowly pump the brakes until bubbles stop. I always started wiith the wheel farest away from the cylinder and working forward. I use clear tubing from Lowe's plumbing department so I can see the air in the line. Once it stops bubling, move to the next bleeder.

Achias · 10-13-2011, 07:50 PM

Yep, you can also use a power bleeder that pressurizes the system so nobody has to sit in the driver's seat and pump all day.

In either case:

DON'T ALLOW THE MASTER CYLINDER RESERVOIR TO GO EMPTY LIKE I DID!

It will cook your master cylinder.

I'll find out next week if the master cylinder just needs to be bled, rebuilt, or replaced.

Such a DOOFUS I am!

hdflstf · 10-13-2011, 09:24 PM

Quote:

Originally Posted by Achias

Yep, you can also use a power bleeder that pressurizes the system so nobody has to sit in the driver's seat and pump all day.

In either case:

DON'T ALLOW THE MASTER CYLINDER RESERVOIR TO GO EMPTY LIKE I DID!

It will cook your master cylinder.

I'll find out next week if the master cylinder just needs to be bled, rebuilt, or replaced.

Such a DOOFUS I am!

It's all coming back like a bad dream now.....

You'll need to bench bleed the master cylinder and then bleed the system.