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OBP master cylinder will not bleed
craigdiver - 9/2/18 at 07:06 PM

Hi all, thought I would hook up my hydraulic clutch to make sure my clutch was going to release ok after benn lying unused for a year. This is a new install so only air in system to start with. Connected everything up, filled reservoir with fluid, fitted self-bleeding thing to bleed nipple (opened bleed nipple). started pumping pedal and nothing. undid banjo from clutch cylinder and all i’m getting is a very light whiff of air when pedal depressed. Checked fluid getting into master cylinder from reservoir and all ok. What am I doing wrong?

gary gsx - 9/2/18 at 08:06 PM

Sounds like it's drawing air in. Try a pressure bleeder or I know a pain in the arris try one of the brake cylinders if you haven't already got brakes bleed up


Gary

craigdiver - 9/2/18 at 08:42 PM

had a good rear of t’internet and i’m thinking I have bleed nipple open far too far - 3 or 4 turns - got advice to put some ptfe tape or grease on the threads and just crack it open and no more. Will try again tomorrow but feel the purchase of a vacuum bleeding kit coming soon!

rusty nuts - 10/2/18 at 08:24 AM

Have you over adjusted the pushrod on the MC?,it needs to have a small amount of slack .?You might find opening the bleed nipple for a few minutes will gravity bleed the system , pressure bleeding works far better than vacuum bleeding , an Easibleed kit is around £20. Another way to bleed clutches is to reverse bleed by connecting a hose from a brake bleed nipple to the clutch bleed nipple and slowly pump the brake pedal , just make sure the clutch reservoir doesn't overflow.

rodgling - 10/2/18 at 08:28 AM

Try disconnecting the pipe from the master cylinder and pump the pedal until you get fluid coming out of the m/c. Then reattach the pipe and bleed that once you know the m/c is bled.

craigdiver - 10/2/18 at 09:22 AM

quote:
Originally posted by rodgling
Try disconnecting the pipe from the master cylinder and pump the pedal until you get fluid coming out of the m/c. Then reattach the pipe and bleed that once you know the m/c is bled.


worked perfectly, as advised I took off outlet hose from master cylinder - bone dry - used syringe to fill with brake fluid with pedal depressed. reconnected hose and now able to bleed hydraulic clutch circuit. pedal still feeling a bit spongy and clutch not releasing but thats for another day when I pick up more brake fluid.

Hopefully clutch / clutch plates not seized. Will have it on its wheels very soon so fingers crossed will release when I rock it back and forward in gear with clutch pressed.

steve m - 10/2/18 at 10:16 AM

I had problems with my OBP cylinders, and sent them back, and they replaced them FOC good service

However I didn't admit to pushing them in and back a few times dry, and apparently this can turn the seals round the wrong way, and they will never work, so OBP told me on email

It might be worth contacting them, they were very helpful in my case

steve