Vacuum brake bleed bubbles?

Howdy all! I'm trying to bleed the brakes after a rebuild of calipers & master cylinder and, I've already tried to bleed them by the "pump & hold, open then close the nipple" gravity method. BTW I always made sure that the master cylinder never emptied while bleeding using either method (vacuum method included). I was not satisifyed with the results. The brake lever would bottom out at 1/4" from the grip. So I bought a vacuum bleeder to get a better bleed & tighter grip. The question is, when using a vacuum bleeder should there be a steady stream of fluid coming from the nipple like you see with the gravity bleed, or should it look like the fluid is bubbling out like I'm seeing? The reason I'm asking is, the gravity method results in a steady stream & I get the bubbles with the vacuum method however, after both methods I still don't have a good inch or more travel before my lever reaches the grip, I'm still at 1/4"

Thanks all
Ken

 

Could be sucking air at the bleeder screw. Did you benck bleed the MC after you rebuilt it?

 

I'm not sure if I did a "bench bleed". When I finished rebuilding the brakes, I filled the M/C with the nipples open waited a reasonable amount of time then started doing the "pump & open" thing till I stopped seeing bubbles. I didn't think about air coming from the nipple connection, that could be, Hmmmm? Do you get the air bubbles also while vacuum bleeding too? Any way I've bled the brakes till they're white and, I'm still not satisfied.

 

When you loosen the bleed nipples they leak at the threads. The vacuum bleeder will pull air through there and mix it with the fluid in the bleeder hose.

It's not an issue UNLESS it prevents you drawing the fluid through. You can put Teflon tape on the bleed screws to stop the air leaking.

 

MiCarl thanks! After hearing what Wingnut said too, it made sense to me. What I was seeing was air coming from the nipple threads. I'm a first time user of the vacuum bleeder and, didn't know exactly what to expect. I finally got the system bled to where I'm now a happy camper. I love this place!! Fast, sure, simple answers to problems.

Many Thanks
Cheers
Ken

 

Yeah, even with teflon tape it can still suck a few bubbles of its own and fool you.

I always do the "final bleed" without vacuum to be sure.