Hydraulic Clutch Problems

[arowland]

Guys

I have just fitted a hydraulic clutch conversion to my Sumo. The setup is a standard Rover V8 and SD1 gearbox.

The problem I’m having is that I don’t seam to be able to keep the hydraulic pressure in the system. If you press down hard on the clutch or pump it, the clutch operates and I can select a gear (with the engine running). If a leave the clutch for a while I have no pressure on the pedal. Or if I press down the clutch slowly there is no pressure.

The master cylinder and slave are both new and I have bled the clutch several time so there is no air in the system and i don't have any fluid leaks

I’m thinking the master cylinder is faulty (possibly the seals). What does everyone else think?

Thanks Allan

[wilf]

If you were losing pressure (and hence hydraulic fluid) in the way you describe, then the fluid that had escaped past the seals would be showing up as a leak from either the master or slave cylider.

Is there fluid around the pushrod end of either of those?

[arowland]

Hi Wilf

I don’t seam to be loosing any fluid; I’m just struggling to keep pressure in the system?

Regards Allan

[stu e]

Hi Allan

Have you checked the joints in the pipe to see if any fluid is weeping out. I fitted the magnum kit and didn't get one of the olives tight enough on the flexi pipe which caused a leak.
I also had to fit a 0.75 master cylinder as the 0.625 one suppled didn't move the slave cylinder enough to disengage the clutch

Regard Stu

[arowland]

Hi Stu

Yes I’m sure I’m not getting any leaks, I have checked and rechecked.

The slave does move when the pedal is pumped (to get the pressure up). I have tried this several times with the engine running.

The thing I find really strange is there is no back pressure on the pedal when you push it in slowly. If you push it in quick there is resistance and the clutch operates?

Thanks, Allan

[Purple AK]

Allen. Is the bleed nipple on the top or the bottom of the slave? If it is the latter, You will never totally bleed the system. Just a thought :thumb:

[tonym]

I helped Allan bleed the system earlier today. The slave cylinder was removed and held in such a way that the bleed nipple was uppermost so we're pretty sure that there is no air in the system. The master cylinder is dry and the joints seem dry too. Can anyone suggest a reason as to why the system works if the pedal is "pumped" rather than just pushed? :thumb:

[stu e]

Hi

Can the master cylinder seal be leaking so the piston doesn't "push the oil" as if there is no lip on the seal? IE no external leaks?

Stu

[tonym]

That was a thought that occurred to us Stu, Wanted some feedback though before Allan took the system apart and I took the M/C back :thumb:

[wilf]

Sorry - impossible to move a piston through a cylinder without displacing fluid and seeing a leak. Something is not right here.

Can you observe the level of fluid in the reservoir when you push down slowly on the pedal? My guess is it rises, (and that is where the fluid is going) and that could well indicate a faulty master cylinder.