The old m/c was leaking, put the service kit in it and changed to braided lines. And I can't get any pressure at all. Tried bleeding it and nothing. When you pull in the leaver you can see the fluid being pushed out through the bleed nipple and then getting sucked back in when you release it. Have a one-way bleeding valve on it. Should it not just keep pushing the fluid out in one direction? Could the piston thing in the m/c be in wrong. Cheers

Your one way bleeding kit isn't working if its allowing fluid to be sucked back in!!

I just use a long clear piece of plastic tubing in a bottle with brake fluid to stop air being sucked back in..

Bleeding brakes is a pain though, especially when the lines are dry.

If you have a long plastic tube it helps to suck on it while the lever is being pumped to draw the fluid out, it'll go eventually.

I'd say you have it right if fluids being pushed out...

Where do you live? If your local i could give you a hand.

Shuldn't be pullig fluid back in. Get a syringe with a piece of tube and fix it onto your bleed nipple. Open it up and withdraw your syringe. Close your bleed nipple and keep at it. Twenty minutes later, Voila!

[quote="Neosophist"]Your one way bleeding kit isn't working if its allowing fluid to be sucked back in!!

The fluid is'nt even making it as far as the one way valve. There's about 1" of clear tubing between the bleed nipple and valve. It fills up about 1/3 of the way when you pull in the leaver. Then when you release it just goes back up the bleed nipple. Everything is on tight. Tried closing the bleed nipple and it keeps the same level of fluid in the 1" tubing. Then pump the brakes, pull in leaver, open nipple. And the level just stays the same and when you release the leaver it goes back up the nipple! Have used this system about a month ago and it worked great. Head is wrecked at this stage.

mick.mh2racing wrote:Shuldn't be pullig fluid back in. Get a syringe with a piece of tube and fix it onto your bleed nipple. Open it up and withdraw your syringe. Close your bleed nipple and keep at it. Twenty minutes later, Voila!

Thats a great idea. I'll give it a shot. Cheers.

dar5150 wrote:

Neosophist wrote:Your one way bleeding kit isn't working if its allowing fluid to be sucked back in!!

The fluid is'nt even making it as far as the one way valve. There's about 1" of clear tubing between the bleed nipple and valve. It fills up about 1/3 of the way when you pull in the leaver. Then when you release it just goes back up the bleed nipple. Everything is on tight. Tried closing the bleed nipple and it keeps the same level of fluid in the 1" tubing. Then pump the brakes, pull in leaver, open nipple. And the level just stays the same and when you release the leaver it goes back up the nipple! Have used this system about a month ago and it worked great. Head is wrecked at this stage.

Yes, However, if the system was working the fluid would displace air from the tube, so in order to suck the fluid back in air would have to be allowed back through the 'one way valve'. Most of the DIY bleeders are crap tho tbh as they don't seal 100% (hence your problem).

The syringe method of sucking fluid through is good, once you get the first major air bubble out the way the rest of the fluid will come through no problem and your bleeding system will work muhc better.

It does take a bit of time but you'll get it done :)

Yes, However, if the system was working the fluid would displace air from the tube, so in order to suck the fluid back in air would have to be allowed back through the 'one way valve'. Most of the DIY bleeders are crap tho tbh as they don't seal 100% (hence your problem).

The syringe method of sucking fluid through is good, once you get the first major air bubble out the way the rest of the fluid will come through no problem and your bleeding system will work muhc better.

It does take a bit of time but you'll get it done :)[/quote]

Cheers for that. Have some time tomorrow to give it a go. Could only get my hands on a small 10cm syringe, but its better than nothing.

Brakes are sorted! Used the syringe on it about 20 min ago and it worked like a charm. Was really suprised at the amount of air that came out. It was unreal. Thanks again for your help. Really appriciate it! Cheers.

Welcome mate. The syringe I use is only about 10ml and it works a treat.

Also worth noting is that the bleed nipples are fitted with an O seal. Make sure one is fitted and in good condition. This will ensure that the air is coming out of the caliper and not sneaking down along the nipple threads and spoiling the fun.