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Thanks for helping out with a topic that has been discussed many times before...

My front brake will not maintain pressure. I had taken the fluid out to clean the MC and hose because I am slowly cleaning the whole bike.
I had the line completely drained. I set up to bleed (restore fluid to) the brake by attaching a hose to the bleed screw and placing the other end in a container with brake fluid. I pumped (alternating with squeezing the lever and tightening the screw, as described in many tutorials and forums). Here is where I have trouble:

As brake fluid starts to flow out of the nipple, it reaches a point in the tube where the remaining air is not pushed out of the tube, so I have: Nipple, tube with fluid, air pocket in tube, fluid in tube sitting in drain container. After continuing to try many methods of pumping and working the screw, the air pocket just stays there, so I figure the brake line is full of fluid, because nothing seems to be moving out of the tube. At this point however, there is no pressure on the brake lever. Does fluid need to fill the tube? and come out the bottom? Tomorrow I will try teflon tape on the screw, but I havent been able to find a forum where the situation is similar. I cannot pump the lever further to get pressure. Any advice is appreciated.

I never did like the back-and-forth in the tube method. Only time I've used it successfully was to bleed light airplane brakes on an airplane which was known for being difficult to bleed. The end of the tube was routed back to the master cylinder reservoir (that was a LONG tube!)

My sequence is to apply and hold pressure at the lever, open the bleeder, when lever is nearly full stroke, shut the bleeder.
Bring the lever back to position to start another stroke being certain to refill the reservoir so you don't suck air on the return stroke.
This method ensures one-way flow thru the hose and caliper.

You may need to bungee or rubber-band the lever against the grip overnight and do some more bleeding tomorrow.
Holding pressure on the lever for an extended time seems to help shift bubbles up to the master cylinder where they can find their way out when you release pressure. Try to have the master as level as you can for this step even if it means rotating the master on the handlebars.

Others have talked about lightly tapping or vibrating the lines periodically during bleeding to help dislodge bubbles.

You'll get it. It's not rocket science.

Thanks for the routine. I will try that. I read about leaving the lever depressed for several hours, but I was unsure about whether the screw was open or not during that time. I assumed the screw would be closed.

I tried giving the line some bumps to no avail. How many time on average did you think you were pumping the lever? Ill give that a shot tomorrow most likely, maybe try the teflon tape too incase air is leaking around the screw as I open it.
I am really hoping I can get it done.

Once you have bled the system it takes a few pumps of the brake lever to build the pressure up (nipple stays closed the whole time). If that happens then definitely do the ziptie trick of leaving the lever fully depressed overnight.

jbethune wrote:Thanks for the routine. I will try that. I read about leaving the lever depressed for several hours, but I was unsure about whether the screw was open or not during that time. I assumed the screw would be closed.

.

Definitely closed.

I changed out the single brake hose on my BMW about 5 years ago. That particular bike took maybe 10 lever pumps. The lever doesn't push a large volume of fluid on each stroke. Be sure and make the strokes slow and deliberate. If you try to 'fan' it it may suck air on the backstroke.

Ok. I will keep working on it today and try leaving the lever depressed. I will let you know how it goes. The help is appreciated.

I left the brake depressed overnight, and it was more firm as I pumped some more. I opened the bleed screw and still was unable to get flow from the bleed screw all the way out of the tube. I left the brake depressed again and will check after work and see if I can get it up to pressure again. If not, I suppose I will try the teflon tape on the threads next.

Hello Jeff and welcome to the forum. Have you tried to fill the line from the caliper? There are kits out there for as little as $18.00. I think a Google search is in order.

jbethune wrote:I left the brake depressed overnight, and it was more firm as I pumped some more. I opened the bleed screw and still was unable to get flow from the bleed screw all the way out of the tube. I left the brake depressed again and will check after work and see if I can get it up to pressure again. If not, I suppose I will try the teflon tape on the threads next.

"all the way out of the tube" has me puzzled. You can only pump small slugs (the stroke of the master cylinder piston) of fluid out of the bleeder using the open/shut bleeder method I described. If you are using a clear plastic tube you should be able to see whether there is air coming out or not. As long as fluid is moving thru you are doing it right and all the parts are working right. If fluid is not moving then perhaps the master cylinder isn't working right.

Pressurize the line with the lever, then open the bleeder, let it run until the lever is nearly to the handle then shut the bleeder. Let the lever return. Repeat. It's a lot easier to do than explain it.

The cap is off the master cylinder when you do this right?