Bleeders sucking air?

[jlwdvm]

Is it possible for bleeders to suck air around the threads and then expel it with the brake fluid during bleeding? I have Wilwood 6 and 4 piston calipers with a completely new system on my Firebird. The brakes work good enough to drive the car, but there still doesn't seem to be the level of stopping power I am expecting from the manual system that Ron Sutton put together for me. I have bled several times, but don't know what to expect from pedal feel with the manual system. It doesn't feel like there is obvious air in the system, but the brakes feel vague when stopping (if that makes sense). I decided to gravity bleed last night and started at the passenger rear inside bleeder. I was watching the fluid flow and every once in a while I would get a bunch of bubbles coming out with the fluid.....then it would be back to straight fluid. When the bleeders are loose enough to get flow, they are also loose enough to wiggle. I decided to wipe some grease at the base of the bleeder to help seal it off from the outside. I still would occasionally get bubbles. After extensively bleeding the passenger rear, I moved to the driver's side and seen no bubbles...haven't done the fronts yet. Just wondering if I could have had that much air in the system and still have a fairly decent pedal...or am I sucking air around the threads of the bleeder and then seeing them come out with the fluid?

[rallystyle]

I have seen the air bubbles when bleeding systems before. it will go by the threads of the bleeders. when i did my el camino i tryed vacuum bleeding it, gravity bleeding it and just the normal press and bleed. i could not get a good pedal. talked to my step dad and on his plane he reverse bleeds it. so what i did was unbolt the master and leaned it forward so the fill ports where at the high point. then used a oil can with brake fluid with a hose fitted to the brake caliper bleeder. pumped the brake fluid in and could hear the air bleed out of the system from the master. now my brakes are solid.

[jlwdvm]

I got to thinking...if there was leakage around the threads, wouldn't brake fluid be coming out around the threads instead of air getting sucked in and around? I've used a vacuum pump before as well. That will be strong enough to suck air between the tubing and the bleeder nipple, as well as around the threads. I also reverse bled this car after I reinstalled my Wilwood master (after it went back for the recall rebuild).

[David Pozzi]

Yes, air can be sucked past the bleeder threads when doing a gravity bleed or whenever a hose from the bleeder runs downhill. I use teflon tape on the threads to try and seal them. It's not 100% effective but it helps.