clutch bleed issue

[waltmgb]

I bought the clutch kit from Moss and replaced the master and slave. Fluid is being fed to the slave but seems to be an air leak as much air keeps coming out of the slave along with the fluid. Checked connectors and all seem tight, no apparent leaks. Pedal to floor, open bleeder, fluid comes out, close bleeder, pedal up. Repeated numerous times. Also pushed slave piston in, open/close valve, bleed as above. Still more air and no clutch action. Ideas?

[Ian F]

A difficult one!
Make sure you aren't opening the bleed screw too far, use red brake grease on the bleeder threads, and use a long tube from the bleed nipple down into a jar with brake fluid in it. These things should stop air being drawn back in via the bleeder.
If all connections are tight, and the hose is good (new?), Then the Master Cylinder must be drawing air?
Did you buy the best quality OEM, if not, then suspect a manufacturing or assembly fault.

Ian F

[Vic Butler]

Clutch hydraulics can be notoriously difficult to bleed. Try using a vacuum bleed system, much safer than a pressure bleeding system.
Otherwise as Ian suggested it could be a faulty master or slave cylinder.

[waltmgb]

Thank you for the ideas. Master, slave, and hose all included with the kit. All were replaced in the car. Master cylinder is a real bugger to change. Original issue was slave leaking so maybe I'll swap the master back and see what happens. One other thing, the kit came with three copper washers, 2 of which fit on either side of the banjo bolt. I could not find any spot that the 3rd one fit. Any experience with that or should I call Moss and ask them?

[Ian F]

Have a look at the exploded diagram in the Moss parts catalogue for the washers, otherwise call Moss. Sorry I can't remember more about them!

Ian F

[Charles Farran]

Make sure the bleed screw is in the correct hole of the slave cylinder, i am aware that it may be in the incorrect hole to ensure the cylinder fits in the packaging it is supplied in. (Mine was & only realised when trying to bleed the system with a neighbour who spotted it)!
Cheers
Charles

[Not_Anumber]

I had quite a job bleeding the original Lockheed clutch MC and after some research I decided to bin it rather than rebuild and got hold of a Girling type MC for an MGC & big Triumphs.

Bad points,
it took 10 mins with a Dremel to make it fit the pedal box, not a problem as I knew it would be required.
Filling the reservoir needs a small funnel as it sits slightly further back. This does reduce the chances of spillage though.

Good points:
Cheaper
Easy to bleed, right first time
Tougher part, made for heavy duty use.

[waltmgb]

Thanks again for all the replies and suggestions. I did transfer the bleed screw as it was in the wrong spot. Swapped the original master back in and all is well now. So the new master was feeding air into the system. Manufacturer defect I'm assuming. Although the thought of changing to a heavier duty and easier to bleed system sounds intriguing I think I'll stay with the current setup for now since all is working. (and return the faulty master to Moss)

[Thorners]

Well, what a nightmare this issue can be, as anybody who's experienced it will testify. I last did it 8 years or so, when I resealed a leaking slave, awful rigmarole then, and worse this time.

After winter's lay-up, Jill's B started straight away (on a C-Tec), checked the fluids, rad OK, brakes OK, oil OK. Clutch not so as it was all over the garage floor.

Ordered a Delphi OE quality slave and fitted it with a new braided hose ☆, tried to bleed, more air than fluid. Further delving revealed a trace of fluid in the master cylinder boot, so off with that, clean & re-seal, off we go again. When refitting, I put the nut and spring washer on a magnetic screwdriver and poked it through the bolt hole, put a finger on, and aligned with the bolt & tightened. Bit fiddly but it worked.

Anyway, after two days of trying to bleed steadily, and nearly 2 litres of fluid later, serious Googling was needed. There are many recommendations for methods, some of which we'd tried unsuccessfully. We eventually found a YouTube from Andy's MG Adventures (thanks Andy), where he eventually called in his pal Dave, who I guess is a retired mechanic.

OK, day 3. Dave's recommendation is to use a Vizibleed, which has a one way valve fitted, and pump the pedal hard and quickly. Righto, give it a go. I filled the mc reservoir, initially Jill pumped fairly steadily whilst I slackened & tightened the bleed nipple, to get some fluid round and into the slave. Tighten the nipple and refill the mc every 3 rounds of pedal up/down, holding down on the third till the nipple is tightened.

Once a fair bit of bubbly fluid comes through, go for it. Wife bangs pedal down, and releases it a bit more steadily, repeat, repeat, hold down & tighten nipple, refill mc. Jill felt some 'pedal' after first three, keep repeating until air stops coming out and the pedal is firm. This worked for us, and hammering the pedal down & repeating quickly chases air out the system, it doesn't have time to float back up the pipe.

As a final check, I forced the slave piston backwards with the bleed nipple open, glad to report no final trapped air.

Start your B, and off you go, good luck.

Tips- 1) Put a tiewrap round the clear pipe/neoprene tube junction on the vizibleed, or get soaked in dot4 if your missus is as heavy footed as mine. 2) We found it was still more effective to open/close the bleed nipple, especially when priming an empty system - though don't during the vigorous pumping phase as it's the pedal force and speed that forces the air out.

☆ When fitting the slave, fit the hose & copper washer to the slave first & mount to the gearbox. Offer the hose up through the bracket & fit the spring washer and nut finger tight. Hold your spanner on the hose nut under the car and get your mate to offer down the correct socket and 2 extensions, and tighten whilst you hold the hose nut in position. Then very carefully fit the clutch pipe union nut with your fingers to prevent cross threading. Tighten as necessary.

[Bumpa]

Bleeding the clutch can be tricky because you are trying to make the air bubbles go downwards when they want to go upwards. Here's what I have done on several older cars and it has worked first time everytime. With master cylinder empty, connect an Easybleed kit to the slave bleed nipple. Fill the Easybleed bottle with fluid. Connect the spare tyre to the bottle with no more than 10 psi in the tyre. Open the bleed nipple and go back up top and peer into the reservoir with a torch. Once fluid starts to fill the reservoir, dive back under and close the bleed nipple. Has worked everytime for me and takes no more than 15 minutes work, plus of course you have to reinflate the spare tyre!