Brake pedal / bleed question
 

I installed speed bleeders and bled the brakes this weekend (and it was a pain since I have not figured how to safely jack up the car so that it is on 4 stands with a 4 wheels removed. I had to do 2 wheels at a time instead).

All went well, all the cloudy 35,000 mile fluid is out and the nice new blue is in, but the pedal feel is off. All the fluid was changed, no bubbles in the fluid, no visible fluid leaking out of the bleeder valves or threads. When the car is not started, the break pedal feels nice and firm, and does not push in very far under pressure. When the car is started, the pedal is firm and stops, but then very slowly continues to drop for quite a ways. For this to occur, you have to really be pushing on the brake pedal as hard as you can, and it does not go to the floor like when bleeding.

On the road, the car feels fine. My question is, is that the normal pedal feel? Could a few of you try out your brake feel with the car off and on and see if the pedal feel is normal, ie, does it drop further under power than when the engine is not on? Thanks.

triptronic or manual?

Manual tranny

You still have some air in the system.

Since you bled them on an uneven surface, and didn't use a pressure bleeder, it would have been very easy for some air to remain trapped in the system.

Also, if you have PSM, Porsche states that a PST2 or PIWIS tester must be used to open up the hydraulic valves in the ABS unit to remove any air trapped in there. Since I don't have PSM, I cannot say how absolutely necessary this is, but both the Porsche Factory manual and the Bentley direct you to do this.

When bleeding using the pedal pumping method, it is possible to blow the master cylinder, unusual, but it can happen. If the pedal doesn't drop to the floor, yours is still functioning.

A spongy pedal almost always indicates air in the system. When flushing the brakes on my Boxster (pressure bleeder, level, on stands), I found it was necessary to pump at least 2 liters of fluid through the system to remove all the air and restore the pedal feel.

That must be it - it is an 05 with PSM.

I will re-bleed with more fluid to see if that solves the issue. If not, I will bring the original bleed valves to my independant shop and get it bled.

Thanks for the response - Jay