I can not get a solid pedal on my 87 S4. Here is what I did:
filled reservoir went to back right opened back right outside valve. Had SO pump to the floor and hold down until I locked off. Repeat 10-15 times.
Went to rear left and repeated only on the outside valve. 10-15 times.
front right only outside valve.
Now, I am not seeing any air or spitting at the valves but I also don't see fonts of pressure when my wife pushes the pedal down with the valves open. I am getting blue out solidly at every valve. Am I missing something (like the prop valve in the 914) or a booster?? or do I just need to keep bleeding?? or am I doing this all wrong? Done this before and it always worked.~M
BTW I did get the fuel leak fixed. Had to put the monkey on the nut that holds the line going to the fuel filter...cheater bar finally got it to stop. ~Thanks All for all of the replies.~M
Take out bleeders. Decrud bottom of hole and conical face of bleeder. Have wife put thumb over hole while you do this or make a little plug so as to minimize mess. Re-bleed and retighten bleeders. If they feel loose you may be bypassing fluid. This gives the pedal a weird feel. Also, sometimes when you move a ton of fluid through the system you can catch a piece of crud in one of the master cylinder seals. Only repeated flushing will fix it and that is iffy. Sometimes disassembly and cleaning is the only thing that will work.
Depends upon what the pedal is doing.
If the pedal simply sinks slowly to the floor, but there is no external fluid leakage, the master cylinder is bad. Often, the pedal will catch and hold if you stab it hard, but will sink slowly with moderate pressure. If the pedal is simply very soft, but doesn't sink all the way to the floor, you may still have air, or the master may be bad.
Sometimes, if you use a speed bleeder (vacuum / pressure venturi based), the threads at the brake bleeder allow air to enter the system when you raise the pedal. If the standard procedure fails you may want to go the old way by pushing the pedal down, closing off the bleeder, raising the pedal, opening the bleeder again, and repeat until absolutely no more bubbles leave the system. PITA, but works great. Needs 2 people, sure.
One more option is to use a oneway valve and a short hose on the nipple. The oneway valve submerged in some brake fluid in a catch bottle. It you open the nipple just a tiny bit, you'd be ok. And it is an easy job for just one person. I always do it like this with good results. ps: on the 1989- models you can even do that without removing the wheels.