Unable to bleed brakes. Help!

[qwertyqewrt]

2008 KTM 250 xcf-w. So on my last ride i noticed i pretty much lost all rear brakes. I figured the fluid got low and air in the line. I took the rear reservoir cover off and it was full. Next I tried to bleed the brakes and couldn't get any air to come out of the pipe. I then tried to backwards bleed with a large serenge and was unable to pump backwards up into it. I removed the nipple to sere if it had dirt/debrie in it and it was clear. I can pump the brake with the nipple uncsrewed slightly and it pumps air but no fluid through it when the reservoir is all the way toped off. Any ideas on the problem here?

Thanks!

[dirtrider 11]

what works best for me is to force fluid up the line tell it fills up the reservoir.that way you don't have to bleed the brakes

[qwertyqewrt]

I tried that witht he serenge and it will not go up the line.

And yes I loosened the nipple.

[Greg Y]

losen the bleeder and leave the wrench attached. from the bleeder run a piece of clear tubing or vaccuum line into a container with a bit of brake fluid in it. with the bleeder loose, pump untill fluid runs air free and clear....keep in mind to fill the res before it sucks air. when it is clear and air free, close the bleeder before removing the hose.......done deal.

[JTLS]

If the res was full and you lost the brakes while riding you probably need a master cyl rebuild kit. If you do whats been mentioned with no luck you'll need a kit. Take the master cyl apart and make sure there are no folds or nicks in the piston seals, they don't have to be huge so look carefully.

[jpkoepse]

Yeah check master cylinder... look for bits of rubber.. and like they said the holes can be really really small so look hard

[Octanee]

i had this issue, and could not resolve it, it got fixed by the dealer, basically, i had my bleeder cup for the job, previously the nipple came loose some how and i lost brake fluid, what i had done was, yeah, you do the bleed, fill up res, put the cap back on, tighten it, loosen the bleed screw and push pedal down, and i repeated it for 2 whole hours, still the brake did not work, so dealer did it, and they got it going, not sure what i did wrong, but man that was not fun

[MTO]

If you can't squirt fluid up the line with the nipple valve cracked loose, you probably need a new valve. They have a little check valve ball up in there that can get corroded frozen stuck in place. If the brakes are failing on long downhills, the fluid is too old and over heating too quick. Keep squirting fluid up the bleeder line until all new fluid is in the system. If all this fails, it's probably the master cylinder or the caliper.

[R.D.]

There are no "check valves, balls, springs or any other moving parts" in the bleeder screw.

Edited May 1, 2011 by reptile dysfunction
Removed a flame.

[MAZMAN]

try by first undoing the banjo bolt thats connected on the master cylinder, just like you would bleed normally(imagine the banjo bolt is your bleeder nipple).

Once you get air out of there, continue down then to the caliper.

You will of course spill fluid where ever your banjo bolt is, so try to put a bucket or such under it to not spill all over your handle bars etc.

[MTO]

There are no "check valves, balls, springs or any other moving parts" in the bleeder screw.

Oh I was thinking of a grease nipple. But I've had them so full of crud that fluid would not pass and had to change them....and what stopped you from flaming me? Bring it!

[MELK-MAN]

Oh I was thinking of a grease nipple. But I've had them so full of crud that fluid would not pass and had to change them....and what stopped you from flaming me? Bring it!

a "chill pill" is in order bro. In a pretty lighthearted way he was pointing out a fairly well know fact. If there wa a check valve, ya wouldn't need to close it off when bleeding without a mighty-vac or one-way valve attached.

I like the post early on that described how to bleed brakes.. cleary that poster didn't even read the original posters comment, just the headline.. L)

To the original poster, if the bike were older, i would guess the master cylinder needs the rebuild kit. Once the plungers wear in the cylinder bore, the fluid is just wooshing past the rubber plunger and not creating any hydrolic pressure. Very common on older bikes, or newer bikes with lots of hours. Look for any leaking around the line fitting, i have had rear brakes fail in BOTH manners i just described. FItting was leaking, and on 2 occasions (almost 1000 hrs on my 04crf450 of woods riding) had to rebuild the master cyl. All it needs are the 2 rubber cups, but you have to buy the $25 kit that comes with a sprin, circlip, piston and the rubber things that are the only worn part.

It also REALLY sounds like there is air in your line. It is hard to bleed a rear brake with the cylinder still attached, as the hose has a high spot. Seems air gets trapped there unless it is a small amount.

Also look at the caliper for any issues, did a brake pad come out of place, are the pads worn to the point the piston is further than usual? Leaking of anything can kind of be ruled out as you said the resiv. was full..

[R.D.]

Wasn't really a flame as much as a smartass answer that seemed unnecessary after reading it ,so I deleted it. Although I'm sure there are others, heres a link to a thread about bleeding brakes. Couple of pics at the end. Easy and it works every time.

https://www.thumpertalk.com/forum/showthread.php?t=876625&highlight=spydergirl

[MTO]

a "chill pill" is in order bro. In a pretty lighthearted way he was pointing out a fairly well know fact. If there wa a check valve, ya wouldn't need to close it off when bleeding without a mighty-vac or one-way valve attached.

I like the post early on that described how to bleed brakes.. cleary that poster didn't even read the original posters comment, just the headline.. L)

To the original poster, if the bike were older, i would guess the master cylinder needs the rebuild kit. Once the plungers wear in the cylinder bore, the fluid is just wooshing past the rubber plunger and not creating any hydrolic pressure. Very common on older bikes, or newer bikes with lots of hours. Look for any leaking around the line fitting, i have had rear brakes fail in BOTH manners i just described. FItting was leaking, and on 2 occasions (almost 1000 hrs on my 04crf450 of woods riding) had to rebuild the master cyl. All it needs are the 2 rubber cups, but you have to buy the $25 kit that comes with a sprin, circlip, piston and the rubber things that are the only worn part.

It also REALLY sounds like there is air in your line. It is hard to bleed a rear brake with the cylinder still attached, as the hose has a high spot. Seems air gets trapped there unless it is a small amount.

Also look at the caliper for any issues, did a brake pad come out of place, are the pads worn to the point the piston is further than usual? Leaking of anything can kind of be ruled out as you said the resiv. was full..

I wasn't attacking him, just defending myself. He was right about the bleeder screw, I was wrong. It was in the 'reason for editing' where he said "removed flame" that got me. I saw what he wrote before he removed it. Nothing light hearted about it.

[the_dixtar]

I had a similar issue last week with my rear brake, I ended up getting a rebuild kit for the master cylinder and reverse bled them backwards and job done ?

[XpressCS]

I had this happen to one of my brakes before. It felt very weak, almost to the point where it didn't work. I pulled it all apart and discovered that there was dirt and crap shoved into the master cylinder.

So after cleaning the thing with wd-40, I put it back on and began the bleeding process. Basically, it wouldn't suck fluid into the cylinder or into the lines. You have to open the bleeder valve, push on the brake pedal, hold it, shut the bleeder valve, and let go of the brake. Repeat.

Took me about 10 minutes, but it bled through, and it works great, locks the wheels up very easily if I'm not careful lol.