Bleeding unsatisfactory

[MarkieB]

I know it's not my Bleeding technique, as the brakes were Bleeding well, so it looks as though the Bleeding clutch isn't Bleeding proper

Here are the symptoms:

Clutch was getting progressively less effective, crunches/non-selection on gearchanges, unless it was pumped; 1, 2, even 3/4 times.

At the end of a long drive the other day, while manoeuvring in the car park, I pumped the clutch say 4 times at one stage, it then reached a point [pedal halfway down] when it wouldn't go down further. The biting point was in a different place [higher up?] when I released it, too.

On checking it before bleeding, it behaved similarly, although after several [dozen] pumps. I then opened the reservoir lid; after a few seconds there was a sound of sucking air/fluid, the fluid level, that had looked quite low for those few moments, suddenly raised, returning to 'normal'. So I think there's a big air bubble in the system, I proceed as planned to the bleeding. However, even with the bleed screw really loose, there's no sign of fluid emerging. Has anybody had similar symptoms; what could it be?

For bleeding the clutch, I'm simply pumping the clutch pedal, although clearly the effect is different to pumping the brake pedal for bleeding, as there's basically less resistance?

cheers

[white90]

sounds like the slave cylinder is on its way out

[rtbarton]

Or even the Master Cylinder

To be honest if you've lost fluid it could be either, if pressure isn't building up it is most likely the master cyl.

It sounds as though your system is pretty well gone so I'd change them both for brand new genuine parts.

[v8bertha]

are loosing fluid after you've bled the system?

Easy way to check... is there hydraulic fluid raining out of the wading plug hole in the bell housing?

As White90 says, sounds like the clutch slave has gone kaput

Both slave and master cylinders are quite cheap if getting oem bits.

Edited December 22, 2005 by v8bertha

[Mo Murphy]

Remember to change both master and slave cylinders together or you'll be doing this again soon

Mo

[robhybrid]

Although I suspect the clutch master cylinder : ---

How old are the clutch components?

Are we talking about your 110?

An old 110 on an original clutch fork could well have worn through the mild steel pivot point in the middle of the clutch fork.

[Bush65]

I know it's not my Bleeding technique, as the brakes were Bleeding well, ...

... However, even with the bleed screw really loose, there's no sign of fluid emerging. Has anybody had similar symptoms; what could it be?

For bleeding the clutch, I'm simply pumping the clutch pedal, although clearly the effect is different to pumping the brake pedal for bleeding, as there's basically less resistance?

cheers

Regarding - no sign of fluid emerging. The passages in the bleed nipple may be blocked.

Sounds to me like there is a problem with how you are bleeding it. Clutches can be harder to bleed than brakes.

Pressure bleed always works best.

However if you can't a access the equipment for pressure bleeding, a useful alternative technique for bleeding the clutch is to run a clear line from the bleed nipple into the reservior on the clutch master cylinder. The end in the reservior is kept below the fluid level so that it does not suck air back into the line.

You did not mention what gearbox you have. The clutch forks for R380's are prone to failing, due to wear at the pivot joint.

[robhybrid]

I have replaced worn clutch forks on (short belhousing) lt77's

[MarkieB]

No reall fluid loss at all that I've noticed as a matter of fact; It's the 110 [LT77]. I'm supposing it's the hydraulics/cylinders rather than the fork from the fact that it responds to pumping. There's so much raining from the flywheel drain plug it isn't clear what percentage is oil/ what percentage is hydraulic fluid.

I've got a one-way bleed valve kit, it works for the brakes as I say, so should work for the clutch. Blocked nipple is a vague possibility although with the sucking, it sounds as though it'll be at least one of the cylinders huh?

Just checked the prices of cylinders, cheers Dan, it looks as though it'll be alright after all, less than the price of a few gallons of diesel

[MarkieB]

Regarding - no sign of fluid emerging. The passages in the bleed nipple may be blocked.

with luck, it looks as though that is mostly all it was. Stands to reason, when you think how the bleed nipple is placed, virtually directly behind the wheel, in the spray/dust.

The fluid is/was a filthy cloudy grey too, I've replaced a large proportion of it, looks as though it hadn't been bled for a while.

cheers Bush

[Les Henson]

The grey in the fluid is most likely alloy particles - Master cylinder wear normally.

Les.