ABS brake bleed

[Robert]

I have a 95 Legacy wagon AWD. I recently bled the brakes the old
fashioned way (pump, hold and bleed). When we were through the pedal
was nice and firm. As soon as we started the car however, the pedal
went soft. I'm guessing this must be something to do with the ABS
system, but its just a guess.

Help

 

[Ed P]

I have a 95 Legacy wagon AWD. I recently bled the brakes the old
fashioned way (pump, hold and bleed). When we were through the pedal
was nice and firm. As soon as we started the car however, the pedal
went soft. I'm guessing this must be something to do with the ABS
system, but its just a guess.

Help

Robert,

Do the brakes feel spongy while driving?

Brake feel is masked to some extent by the power assist on power brakes.
I normally evaluate sponginess only after bleeding off the power brake
assist with the engine OFF.

Ed P

 

[Robert]

Thanks for responding Ed, yes the brakes are spongy with the engine
running. After reading your post I pressed the pedal to bleed the
boost (I think) and the pedal is nice and tight afer starting its
mushy again. It feels excesive like its softer than it was whe I
purchased the car a few years ago. Is there a set distance the pedal
should travel, coould the boost be malfunctioning?

Thanks again.

 

[Ed P]

Thanks for responding Ed, yes the brakes are spongy with the engine
running. After reading your post I pressed the pedal to bleed the
boost (I think) and the pedal is nice and tight afer starting its
mushy again. It feels excesive like its softer than it was whe I
purchased the car a few years ago. Is there a set distance the pedal
should travel, coould the boost be malfunctioning?

Thanks again.

Robert,

I recently replaced the rear pads and manually bled the entire brake
system on my '96 Legacy Outback and had no problem related to the
presence of ABS.

If the pedal is hard with the engine OFF after you have pumped the pedal
several times to remove residual assist vacuum, you have probably bled
the brakes OK. But, if you feel your brakes are spongier than before, I
would try bleeding them again anyway. Be sure the calipers slide freely
-- especially, if you have had any of the calipers/pads off.

Some tips: use a hand vacuum brake bleeder if you can get one. Or, get
a length of tubing (preferrably clear) that fits snuggly over the
bleeder fitting. Put one end over the fitting and keep the other end
submerged in brake fluid so that air cannot get sucked back into system.
Move the brake pedal slowly and deliberately when bleeding to avoid
creating any bubbles in the fluid.

Ed P

 

[hippo]

Don't know if you followed this sequence or not, but just in case -
otherwise ignore! You have to bleed both ABS bleeder valves before
anything else. They're on the ABS modulator - rhs inner guard just ahead
of the airbox. Start with the Primary (towards front of car), then
secondary (back of unit), THEN do all wheel units in the folowing order
ONLY - driver's side front, pass side rear, pass side front, driver's side
rear. Cheers

 

[hippo]

Sorry - that was for rh drive (Aus). If your master cylinder is on your
driver's side go with what I said - else read passenger for driver and vv.
Cheers