milehigh6080

Hello all,

I replaced my front brake pads last night and I think I made a big boo boo in the way I did it. Once the calipers were off, I cracked the bleed valve while I compressed the piston with a C clamp. This made it much easier than fighting against the head pressure in the lines, but the boneheaded thing that I didn't consider is that a bunch of air would get back into the lines before I closed it.

This procedure wasted a lot of fluid and my reservoir got pretty low. So now I have air pretty much everywhere . . . no problem, I'll just bleed it out. So I did that in the right order, started at the right rear, left rear, right front, left front, and got all the air (so it seemed) out of the lines and calipers there.

With the car shut off, all is well, I have plenty of pedal pressure and it seems to be working just fine. Then I turn the car on, press the brake pedal and it goes right to the floor.

So what am I missing here? What else needs to be bled that operates when the car is running but not when it's off? Why do I get good pedal feel with the car off, but a pedal that goes to the floor on the first press when running? With the car running, I can pump the pedal and get it to come up to where it's supposed to be, but if I wait a minute or two it'll go straight back down to the floor.

Guess I screwed something up, live and learn, can anyone point me in the right direction?

Thanks.

nunya

Bleed the clutch.

milehigh6080

It's Tiptronic

Shard7

With the engine running the vac booster will make the pedal a lot easier to push, so any air in the system is easily compressed. With the engine stopped, you can pump the pedal and build up pressure; it'll fell firmer once the air's been compressed to a certain point.

Bleeding sometimes takes a few iterations to be fully effective, especially if you got a bunch of air in there. Be sure to keep the fluid reservoir topped off and be careful not to suck air back in through the bleeder valves.

gh0st

that will allow you to push the piston back in too

milehigh6080

oh yeah, i definately learned my lesson

Carson (K03x2)

Time for a 2 man bleed/pressure bleed.

milehigh6080

My dad and I have bled them a good three times now and still have tons of pedal travel. I've even bled the master cylinder. I don't know what else I could be missing, but there is no doubt that there's A LOT of air somewhere in the lines. Guess I need to take it somewhere that does pressure bleeding and have it done.

MikekiM@PureMS

Cycle the ABS pump.