Outer Limits 4x4 Board

I have just replaced the clutch and master cylinder in a 1992 3.2 V6 jackaroo/trooper. the clutch went in fine, the pull out bearing is attached to the clutch fingers, but despite bleeding over a litre of brake fluid through this thing, and no apparent bubbles out of the bleeder, it has hardly any pedal, and hardly disengages.

so far I have: pushed the actuating cylinder piston right back as far as it will go to minimise the volume in the actuating cylinder, and held it there with a block of wood, then forced the fluid through the system with compressed air at 20psi applied to the top of the reservoir, then performed a regular "bleeding" procedure, with an assistant pumping the pedal while I watched the bleeder tube and worked the bleeder valve. This combination released a lot of air from the system but it appears there must be a lot more in there still :(

I do not have a manual for this vehicle; I have set up the pushrod with approx 5mm pedal freeplay, and there are no leaks around the slave cylinder. the cylinder pushrod does not appear to be adjustable although giving it some length would probably solve (or at least mask) the problem.

any help greatly appreciated.

cheers

Brian

ok in addition to the above, I have removed, dismantled, cleaned, inspected and reassembled the slave cylinder, then left it dangling off the banjo bolt on the soft line, with a clamp on it to stop the piston popping out. under these conditions it should be possible to bleed it up to a rock-hard pedal, but I can still get almost no pedal at all. have put about 2 litres of fluid through it, under pressure and just running through. no bubbles. no pedal. please give me some ideas.

Have you tried reverse bleeding? Rig up a bottle full of new fluid higher than the reservoir with a long hose on it that will reach the bleed nipple on the slave cylinder and refill the system from the slave upwards. I would imagine this would float the air out of the master cylider.

You said any ideas. Just a thought and have never done this.

it's so crazy it just might work... I'll try anything at this stage.

why are you reading the Isuzu forum??

If your clutch cylinder has a bleading nipple, try that as well

berazafi wrote:If your clutch cylinder has a bleading nipple, try that as well

it doesn't, but I cracked the flare nut on the hard line (no mean feat on the V6 with the cylinder installed to the firewall let me tell you) and bled it out there, too.

keep the ideas coming.


at the moment I have set it up with a 2 metre bleeder hose recirculating the fluid from the bleed nipple on the slave cyl back to the top of the master cyl reservoir. the slave cyl is dangling from the soft line, with a clamp on it holding the piston about 80% in, to minimise the volume and create tyhe situation where if all the air is removed, the pedal should be rock hard.

I keep bleeding the fluid around and around and it appears there is always tiny air bubbles in it, almost emulsified, so I have to stop every 20 pumps or so and let the bubbles rise to the surface in the reservoir.

I have tried pressure bleeding to no avail, do you think vacuum bleeding woild work better?

Slyy question, was the clutch the same hieght as the old one. If it is different then the Hyraulics wont have enough stroke to operate it.

What happens when you clamp off the flexible line, does it go rock hard?

You have replaced the master cylender, yes? Just out of curiousity, is the resevoir sitting in the master properly? If its not it could be drawing air from there.

thanks for the ideas guys. it's fixed now - it just took a LOT of bleeding to get sufficient air out of it, and the pedal pushrod needed a little bit of extra length to ensure proper operation.

with the 'recycle' bleed I had set up, it took about 200 - 300 strokes of the pedal to expel all the air. curious.

dumbdunce wrote: it took about 200 - 300 strokes of the pedal to expel all the air.

Your dog Roxy, she sure is a help in the workshop!

Good to see that you got it sorted.

carts wrote:Good to see that you got it sorted.

that stumpy, he sure can pump hard and fast.