Clutch bleeding my mav...

[Area54]

I'm having hassles bleeding my clutch and restoring full travel of the hyd system.

Story: A few weeks ago while driving, soft line to slave splits, progressively pumps reservoir dry while driving home. Air would have got into master. Next day I went on 3 week holiday, just getting 'round to repair now, about 5 weeks later.

Mav is '92 diesel, with vaccum assist and the secondary bleed port adjacent fuel filter.

I'm no stranger to bleeding hyd systems. Confident there is no air in lines or around the slave piston, I've backwashed the master as well, but it just feels like the air pocket is at the master. No fluid is escaping anywhere - ie vacuum lines, diaphragm, slave piston, master piston. I've got both the nissan master workshop manuals as well as the gregories - both are fairly vague about procedure.

Need another few brains to think this one over.

[JBE]

Just been trough this; replaced master & slave cylinder and the rubber hose to the slave cylinder. I tried to bleed the system myself for hours and went through four cans of brake fluid to no avail. I had a mobile mechanic with a vac bleeder give up on it after hours (lucky, he didn't want to charge me for it). When I dropped it at my workshop, they got it to a point where I could drive the car and just shift if I pushed the pedal all the way to the firewall. They checked everything like master set up to specs, bench bled the master and vacuum and pressure bled the system, but couldn't get it any better.
My car was off the road for the better part of two weeks because of this problem and I was ready to torch it!

Some people had success with counter bleeding the system from the slave to the bleeder nipple near the fuel filter/primer unit, but this didn't make a change to me. I think the problem is that there is an air pocket somewhere in the system that you can't push out. I listened to a guy on the patrol forum and got a hose made up at ENZED from master to slave cylinder which replaced all the factory plumbing; cost me about $80 from memory. Bleeding it on my own took my 10 minutes flat and I have full clutch back. Now, I have a set up, I can confidently bleed in no time at all.

Good luck with whatever you try to fix it.

[Area54]

Good to hear I'm not the only one who has had this issue. I've had the truck 14 years, never had this before, but then never fully drained the lines either. When I did the body lift 12 years ago, I adjusted the firewal bracket that holds the soft line to the slave, to reduce the tension on the hose. I figured when it gave me an issue, I'd get a longer hose made up. My laziness has caught up with me

[Sharp]

Hi All
Bleeding to clutch can be a probem this is how we do them on Patrol's, need 3 people makes it easier (1 topping up the reservoir, 1 on the pedal, 1 bleeding) here is the trick when you call DOWN do not crack the bleeder until the person on the pedal calls DOWN this way you use the back pressure of the clutch to push the air out. hope that helps

[jackass]

Make sure that you adjust out the freeplay on the master and slave also if changing parts . and hold your tounge in the right position lol

[garth]

been here before...real PITA, solution is to either force fluid into slave (oil can and silicon hose) and back bleed up to bleeder and master. if that dosent work I have then taken nozzel off bleed pipe and cap off master, then with a squirty bottle forced a large volume of fluid back through to the master resulting in a "burb" of air back into master cylinder.
Its the loop of pipe over the engine against the fire wall that's causing this, especially when the trapped air is heated expanding it and making it even worse.

good luck

[Sharp]

Quoted from the Nissan Manual


Air Bleeding Procedure
1. Bleed air from clutch operating cylinder according to the following
procedure.
Carefully monitor fluid level at master cylinder during bleeding
operation.
a. Top up reservoir with recommended brake fluid.
b. Connect a transparent vinyl tube to air bleeder valve.
c. Slowly depress clutch pedal to its full stroke and release it
completely. Repeat this operation several times at 2 to 3 second
intervals.
d. Hold clutch pedal depressed, open bleeder valve to release air.
e. Close bleeder valve.
f. Release clutch pedal and wait at least 5 seconds.
g. Repeat steps c through e above until brake fluid flows from air
bleeder valve without air bubbles.
2. Repeat the above bleeding procedure 1 several times

[Area54]

Okay, a bit of closure on this.

I originally had a new hose made up, same as factory circuit layout (keeping the damper hardline up along the firewall, with bleeder near fuel filter). This was where I had the issue, just couldn't get the air out of that damper line.

Got a new soft line made up, without the port on the splitter block for the damper. Bled the system without issue, full travel at throwout lever.

I wanted to keep it factory standard, but honestly if there was an issue in the field, no way that system could be bled with tools at hand, so fat better with the simpler system - without the damper.

[bozwon]

when i did my clutch master and slave cylinders i had a bubble trapped in the firewall hardline after regular bleeding.

i then got a length of clear plastic tubing and put it onto the bleed nipple at the fuel filter, ran it up to the windscreen (held it in place with the windscreen wiper) then returned it to the master cylinder resivior. i opened the bleed nipple 3-4 turns, i then pressed on the clutch pedal quite a few times to fill up the hose, topped up the master and pressed on the pedal a fair few more timesto circulate the fluid. the small bubbles were joining up in the loop hose so the fluid going back to the master wasnt excessisivly aerated. after a couple of minutes i stopped and closed the bleed nipple.

after half hour or so i had a mate press on the pedal to give it a more traditional bleed to make sure there was no more air in the system (i left the tube attatched and full of fluid from previous bleed). there was no obvious extra bubbles.

has been fine for about 3 months and counting