Techniques - Bleeding brakes/clutches
A) Without any tube, 2 persons required
For now, if you haven't a self-bleeder or simple tube,
Then technique (A) is:
Health & Safety - Person at bleed nipple aware of splashes/squirts of hyd. fluid. Wear goggles to protect eyes!
1) Wheel off, jack stands, to get good acccess;
1a) jam up operating lever to stop it moving if bleeding clutch (can help);
2) loosen bleed nipple (good fitting 7mm ring spanner), then just nip back up putting some old cloth around area in readiness;
3) call out to helper ' DOWN' - helper pushes smoothly, evenly to floor and holds there, whilst you loosen bleed screw as pressure comes on;
Note: Excessive pressure on the brake pedal during bleeding could in rare cases lead to master cylinder damage.
4) helper repeats 'DOWN' call when pedal hits the floor at which you quickly nip it back up, calling 'UP', when you have done so;
4a) helper repeats 'UP, when pedal back up, so you know you can then get spanner ready and call 'DOWN' again (try to leave ring spanner in a good position to nip and open bleed nipple enough to bleed a good stream in one turn without removing from nipple);
5) repeat... 3 & 4 till fluid issuing forth without air bubbles or spluttering each time you call 'DOWN' and loosen nipple. Maybe until clean fluid coming out.
6) check and top up reservoir if noticeably down from max. (no need at each repeat of 3 & 4). Consider whether you have achieved result
7) If so remove jam! (helper should never need to, or stand on pedal hard);
7a) If clutch - call DOWN and observe op. lever travel... is it moving a decent amount (as discussed earlier);
8) Does clutch now work better; 9) Does clutch continue to work better or does it quickly degrade again; 10) Pop rubber bellows off slave cylinder to see if fluid is escaping around pushrod/piston. Ditto master cylinder, though should be pretty obvious by now if it is!
B) With a simple tube into a jar with some fluid already in, end below surface
C) With a bleeding tube (any motofax) having a one-way valve at the end
Much easier with a proper self-bleeding tube, just stick it in an empty bottle, open the bleed valve, and go push the pedal smoothly up and down a few times...
Nice if someone can be monitoring at the bleed nipple (with goggles on) to see if spurts of air do or do not come out, that the bleed nipple is open enough to get a good flow (can be sensed by pedal pressure too, a lack thereof, if alone) and when clean fluid starts to come out is usually the point to stop and nip bleed screw back up and go top-up the reservoir.
D) With a pressure bleeder, pumping up master reservoir.
Clutch hard to bleed; empty master; bubbles in master; doesn't seem to bleed
Simon Baxter: Just jiggle the pedal, don't pump, you should see small bubbles coming out of the pipe to the master cylinder. If that doesn't work, press the pedal, keep it down, then get someone to open the bleed nipple, then close it again, release pedal. Keep doing this.
They can be a bit of a pain if you let them run dry, it takes a while to get some fluid in there but once it's in it will bleed up fine. Chances are that if you leave it an hour it will be okay and you should be able to bleed it normally.
Generally I don't press the pedal, just open the bleed nipple and let the fluid flow using gravity.