Clutch slave cylinder bleed

[President Merkin]

I'm having a tricky time getting this job right. MOT guy noted helpfully that my clutch slave cylinder was leaking. I've replaced it & bled it sufficiently to a working pedal. However, I have a very low biting point now, abiiut an inch off the floor & noticeably lower than previously. So I clearly still have air in the system & will have to go back to the job.

I'm using a pressure bleeder & the recommended technique on this car (R53 Mini Cooper S) is to compress the piston which I have done with a jig made up of a couple of long bolts & a bit of wood. It's a bit of a pain in that the only way to test is remove the jig & refit to the car, so if it's incomplete then you have to start from scratch. I will get there with it but after three bleeds & no observable bubbles, it's still not right so I'm asking for any tips & tricks from the old hands I may have missed or could try please.

Bled with the cyclinder angled up toward the bleed screw, tapped the cylinder with a spanner during bleeding etc. Have seen someone suggest wedging the clutch pedal fully depressed & leaving it overnight but not sure of the logic of that?

[RSstuff]

I've seen a couple of youtube videos, where the system has been reverse bled by introducing the fluid via the slave cylinder bleed. Air naturally rises, and escapes via the master cylinder.

Edited by RSstuff on Sunday 3rd March 11:33

[SlimJim16v]

Have you tried doing it the old fashioned way, pumping the pedal?

[President Merkin]

Working solo, so not in a position do do that & don't have the wherewithal to reverse bleed it, Looks like persevering until it's right is on the cards.

[InitialDave]

A pneumatic or hand pumped vacuum bleeder can often be effective for me when dealing with uncooperative brakes or clutches.

[TwinKam]

SlimJim16v said:

Have you tried doing it the old fashioned way, pumping the pedal?

Very rare to be able to successfully bleed a clutch this way, invariably need some pressure or vacuum.
Sometimes the biting point improves after a few pumps/test drive, and sometimes 'blocking' the pedal* overnight helps too... nothing to lose by trying.

• Pump up as much pressure as you can and hold the pedal down to the floor with (a block of wood against the seat front if you don't have) a pedal depressor.

[richhead]

is the slave cylinger lower that the master cylinder? if it is then sometimes just gravity bleeding can work.
cluch bleeding can be a sod at times

[President Merkin]

Hard to say really. The MC is behind the pedal & the SC bolted to the outside of the bell housing. My view is they're roughly the same level, so I've consequently discounted the idea of a gravity bleed. I think on balance it's a case of repeating the bleed until the pedal comes back to normal. Like you say just a bit of an awkward job full stop.