Brake pedal hard when engine is off and soft when on

[98ExpyIdaho]

Brake pedal hard when engine is off and soft when on and there's little braking power. I changed the brake pads, rotors, and changed one caliper. Bled the system three times now but still can't get a normal feeling pedal when engine is on. Also checked for vacuum leaks and found none. Any ideas?

 

[toomanytoys]

A lot of times a hard pedal (when everything is in good order) comes from collapsed brake hoses. They look normal on the outside but have collapsed internally preventing the fluid from flowing normally.

 

[98ExpyIdaho]

By hard I mean it feels normal there;s resistance and pressure when the engine is off. When I turned the engine on I lose all resistance and pressure and the brake pedal goes to the floor. I am wondering if it might be air in the ABS system

 

[Big Brian]

does the pedal pump up? If so then yes there is air in the system

if no you may have a bad master when you bled the brakes did you let the pedal go all the way to the floor? If so thats a good way to wreck the master. When you do that there is a change the seals in the master get pushed past debris that collects in the far end of the master cylinder and that can ruin the seals

some people pump the heck out of the master at first and that is not good. Always start gently and do not let the brake pedal bottom out

 

[93prostar190]

On my 2007 it feels the same way ... I even had the dealer bleed the system once thinking it may be related to the ABS bleed (they have a tool or computer that you need in order to bleed properly I have been told or the ABS does not get bled properly.)

I have a MITY VAC and am tempted to bleed myself .... it feels like when the engine is running the "Assist" lets the pedal travel further and it feels nice when there is no power ...

any other experiences out there?

 

[kythri]

I had to replace the ABS pump twice (using a wrecking yard part) before my spongy-while-on brake pedal issues were cured.

Bleeding didn't solve the issue either time, it was a crapped out ABS pump (or, more appropriately, the ABS pump control module bolted onto the pump, but good luck getting anyone to sell you one of those separately).

 

[98ExpyIdaho]

Wanted to post what the fix was. I had asked for a driver side caliper at the parts store and they had given me a passenger side one. This was making it impossible to bleed completely.