Just finished bleeding the front and "most" of the back and have few questions:

1) If I have an airtight seal over the bleed nip, why can I not just stand at the reservoir and pump the brake lever while making sure the fluid level stays above the point where it would suck air?

2) WTF does it take to get the rear brake to push the fluid out??? I was pumping it up by hand (putting quite a bit of bodyweight pressure on the pedal), only to crack the bleeder and have fluid come out soooo slowly. Didn't seem to make much difference if I pumped 6 times or 16. After about 15 minutes, I got the reservoir empty/filled with new fluid and just called it good.

3) Would the brake fluid be unusable tomorrow if I wanted to give the rear brake another try?

Just fyi, I did this two years ago and don't recall having this problem with the rear brake.

On the plus side, there was no air in the system!

Any tips or suggestions (as always) are more than welcome!

 

1) It will push and suck the fluid around, but not really work out the air. A one way check valve is needed, however a loose bleeder is not air tight. The threads don't seal.

2) is the bleeder plugged at all? What line are you running? Old rubber can swell up inside the hose and restrict flow (although this usually shows up in a semi applied caliper). Also, make sure the feed tube flows enough.

3) if it's clean fluid, why not.

Try opening the bleeder and just push once, close the bleeder and release. Repeat.

 

1. Okay, that makes sense!

2. Don't think so... Lines are the original rubber but never had any issues with binding or sticking.

3. Didn't know how long it would take for it absorb too much moisture from the air. Always hear to not use "opened" brake fluid but never heard what the timeline on it might be.

Thanks!

 

Fluid that starts picking up moisture starts to turn brown. As for bleeding the brakes, I'm a fan of speed bleeders. Makes it easier for single person to do. Essentially attach a hose and pump away, adding new as you need.

 

+1
Here is a cheap and cheerful version of the speed bleeder (a small slit at one end of the pipe)
Just need to make sure the end of the hose is in fluid, stop when no bubbles appear!!

 

1-That's literally what single person bleeders do. Tube going to resivoir. Pushes fluid and air into bottle, only sucks fluid back when letting off the lever. Not the preffered method, especially on a bike where you can reach both things while working. Pump a couple times, hold lever most of the way in last pump, crack bleeder, re-seat bleeder, and let off lever and repeat.
2- Just forget about the rear brake. Its stupid.
3- Not in the least. Goes bad in the bottle at the same rate as your brake system.

 

Appreciate all the suggestions/knowledge! Got the rear taken care of but, in checking the front, I noticed that one of the valves is weeping. I tightened it a little bit more but no luck. Tighten it more? Put something on the threads to help them seal? Just buy a new one?

 

The spec for the bleeder valve is only 4.3 lb ft. Not much. Making sure the threads are clean. Maybe put some thread sealant. I'm not a fan of overtightening. Leads to stripped threads and potential costly replacement.

 

Oh. I might have exceeded that by... a bit. Oh well! I just got back from a short ride, loosened it, re-tightened, and will take a look at it tomorrow

 

I think I might opt for a new one to be on the safe side, esp as you are now an expert at brake bleeding