Internal Slave AX-15 Bleeding

1993 Sport with 4.0L AX-15 NP231 199K.

I cannot get the clutch to bleed completely. I've vacuum bled the thing numerous times without any improvement. I'm pretty sure that it's air, as the engagement point gets closer and closer to the floor as the engine warms up. If completely cool, I have about 1 1/2" of travel which then gets closer and closer to the floor until it won't disengage completely preventing shifting. Letting it cool down, the engagement point slowly comes back to the 1 1/2" point.

I'm sick and tired of this. I just need to know what I'm doing wrong.

Thanks for giving your basic info, gets everyone off on the right foot (or left foot, for a clutch question).

First, any recent clutch work done? Was the flywheel resurfaced?

Don't vacuum bleed your clutch first off. Gravity bleed it initially, then followed by a simple open/close bleed a couple of times. First remove the cap to your master cylinder and top the fluid, then bleed all of the old fluid out by opening the bleeder screw on the slave cylinder. BE SURE NOT TO LET THE FLUID LEVEL GO TO LOW WHEN DOING THIS, you will only get air in your system. So check the fluid level in the master cylinder when the old fluid is coming out. Then once all of the old fluid is out close the bleeder screw on the slave cylinder to a point where its drips around 3 times a second. Let this continue to drip at this 3x per second rate for 15minutes, BE SURE NOT TO LET THE FLUID LEVEL GO TO LOW WHEN DOING THIS. After 15 minutes close the bleeder screw on the slave cylinder, top off the master cylinder and put its cap on, then pump the clutch till you get pressure. If its good, leave it. If not open/close bleed it, to do that simply remove the master cap, press and hold the clutch pedal in(Use a 2x4, floor jack handle or whatever else you can find that presses the pedal tightly to the floor). Then open the valve on the slave cylinder, after its done spewing crap out close it. Repeat this 3-5 times. BE SURE NOT TO LET THE FLUID LEVEL GO TO LOW WHEN DOING THIS, so check after every repetition. Then close everything up and make sure the fluid levels are topped off, pump the clutch several times and you should be good to go.

Also, the slave cylinders (a.k.a. release bearings) are very prone to failure, especially the internal ones. I've replaced 4 to date in my XJ, the first was stock at 190k, then the 2nd one went out 6months after it was installed, the 3rd was a d.o.a. part that had to be replaced immediately since it was defective. Finally I manned up and bought the aluminum housed slave cylinder, I've noticed a huge improvement in shifting over the last 2 plastic ones that were in there. Jeeps tend to be extremely hard on o.e.m. parts and they have a tendency to fail early. Only buy high quality replacement parts for a jeep, TRUST ME ON THIS. I've replaced things 2-3 times by buying cheaper o.e.m. stuff that you get at autozone/ schucks....etc.

The truck is a friends. My personal XJ is a 1995 sport. I put a new clutch, pressure plate, and slave in this one for him a couple of weeks ago. I didn't resurface the flywheel when I did the job, as everything looked good. It may or may not have been resurfaced when the clutch that was I replaced was put in (it wasn't the original, unless 'Made In China' stamps on all the parts is factory ). The old clutch disc was worn completely out, and was slipping under acceleration. So, everything is new inside the bellhousing. I'm not ruling out that something isn't broken that I put in there, but it all looked good.

I'll try your suggestion about gravity bleeding tomorrow and re-post my findings. BTW, is there any specific reason against vacuum bleeding? You seem to dead set against it, so I'm just curious as it's my method of choice as I don't need an assistant (or girlfriend) to help me.

Just personal experience, I've never had any success with vacuum bleeding, never seems to work right. Same with using cheapo remanufactured or crappy o.e.m. brands like parts master, duralast. Anything from starters, brake pads, wheel bearings, suspension/steering components I've done with those cheapo parts and guess what, EVERY SINGLE ONE FAILED. Ok, I'm exaggerating slightly, they all failed but the starter .

my experience:
http://naxja.org/forum/showthread.php?t=87776


My vacuum bleeder is a 100% duty cycle rated 7HG mercury vacuum pump and a big mason jar that I rigged in the garage. I found that the issue was air trapped in the line as it runs above the brake booster. I turned on the vacuum pump and ran two quarts of fluid through it and have never touched it since.

2x on gravity bleeding.

Why not convert to an external slave while you are at it?

souske said:

Why not convert to an external slave while you are at it?

Click to expand...

because you need a new bellhousing to do the conversion. There's nothing wrong with the internal slave, other than you have to pull the bellhousing to maintenance it.

Not my rig, its a friends. My personal XJ is a 1995 and I have the external slave model. I've had issues with it as well that required the tranny to be pulled. The plastic fulcrum for the throwout bearing lever crumbled at a stoplight once. Had to pull the whole transmission to fix a 2 dollar part.

nblanton said:

Not my rig, its a friends. My personal XJ is a 1995 and I have the external slave model. I've had issues with it as well that required the tranny to be pulled. The plastic fulcrum for the throwout bearing lever crumbled at a stoplight once. Had to pull the whole transmission to fix a 2 dollar part.

Click to expand...

Yep, some days you're the dog, and some days you're the hydrant.

Just to let everyone know, the gravity bleeding really didn't do it. Looks like I'm going to pull the transmission back out and see if something is up. I had some red flags with the clutch kit the dude bought, the Duralast (Autozone) one. First the pilot bearing and clutch pilot tool were incorrect. The bearing id and od were both wrong, and the pilot tool was for the included, but wrong bearing. I had a spare new pilot bearing, so I just use it instead. Starting to wonder if some of the other stuff was also not exactly right either.

Ouch!

FYI, Luk Gold is a great clutch kit, comes with a new slave included.

I guessed that would be your reply. I took your advice when I did my clutch last month and got the Luk. I'm going to pull the transmission either tomorrow or the next day and give it a look. Could it be a flywheel that was turned at some point in the past? Is there anyway to know whether or not it has been turned? Like a thickness spec?

I'm getting predictable!

No, I don't have any specs in the thickness. Some machinists will mark the flywheel when it has been turned--sometimes just a small mark with an auto punch in the center area near the mounting bolt holes.

If it has been resurfaced, and more than .001~.003 was removed that could be the problem. One fix is to replace the flywheel. Old Man found a work around by using a Howe Performance MC with a larger bore and piston, it provided more movement to compensate.

That thread was a good one to look through. Also, I noticed that the stock M/C on the 1993 is a plastic unit at 11/16" bore. My 1995 has an aluminum body one with a 17.75 mm bore. That's quite a bit more fluid there. I'm going to swap them around and see if it fixes the problems. If so, he can just get a new M/C.

Reading this has helped me with my XJ. I swapped transmissions to a AX-15 but very limited knowledge. Where is the bleeder screw on the slave cylinder. Also is the slave cylinder a part of the master cylinder? Trying to make my clutch clutchy again but never done it before. Thanks for any help.

The slave is inside of the transmission on the AX-15 I think, not a user friendly location.

On my Nissan-Jeep Franken jeep rig, I learned that pumping the shit out of the clutch pedal about 200 times, then take a 30 minute break, then repeat 2-3 times got the air out of mine when nothing else including bleeding worked. Seems to foam up the fluid, then the foam rises the MC and to the top of the MC bottle.