Clutch not engaging fully

[xj92]

At random, my clutch doesn't seem to be fully engaging. The firmness of the pedal is lost, and pushing it down all the way barely engages the clutch enough to shift, and shifting is very difficult. This only happens sometimes, other times it works just fine. Anybody have any ideas what it would be? Clutch master or slave cylinder? It seems if it were out of fluid it wouldn't work all the time, not just sometimes. The clutch itsef? Same thing as before, can't figure out why it only happens sometimes. TIA.

[jldiaz]

Search the forum on how to bleed the hydraulic. There is a lot of info on this.

[Eagle]

Also, if you post again for more info, check your terminology. My 87 MJ does the same thing. The problem is that the clutch is not DISengaging, not that the clutch is not engaging. It's engaged when you're driving down the road with your foot off the pedal.

[Matthew Currie]

If it happens intermittently, it's probably not a bleeding problem, but a clutch master cylinder problem. The cups in a master cylinder are designed to fan outward a little under pressure, so that they will be very tight on the push, and relax when they retract. When they age, they will sometimes catch properly, and sometimes will not go tight until partway down the stroke, and eventually not at all. A sure sign of this is if the clutch works better if you push the pedal down fast than if you do it slowly.

[xj92]

I've still got more reading to do, but when my slave cylinder went bad last time, the fluid kept leaking out. I checked my fluid this time and it's full, and no changes have been made to the system at all that has worked fine for 2 years, that's why I'm questioning whether bleeding it will do it. It died completely tonight on the way home from work after I started this thread, it wouldn't disengage at all (right terminology this time, I think). I know my slave cylinder was internal and you had to drop the tranny I believe, not sure on the master though. Oh well, I'll read up lon it some more. If anybody has any more input, feel free to share.

[xj92]

By the way, if it helps any, I wasn't able to shift from first to second just by using the shift points this time like I have in the past, I can't shift at all when the vehicle is moving.

[Matthew Currie]

I've still got more reading to do, but when my slave cylinder went bad last time, the fluid kept leaking out. I checked my fluid this time and it's full, and no changes have been made to the system at all that has worked fine for 2 years, that's why I'm questioning whether bleeding it will do it. It died completely tonight on the way home from work after I started this thread, it wouldn't disengage at all (right terminology this time, I think). I know my slave cylinder was internal and you had to drop the tranny I believe, not sure on the master though. Oh well, I'll read up lon it some more. If anybody has any more input, feel free to share.

That's why I think it's the master cylinder. The slave will leak out, but when the master cylinder goes bad the fluid just leaks past the piston and ends up where it started, in the reservoir.

I thought by '92 they had replaced the internal slave with the later external version. On the 95 and 96, it's external. It is, theoretically, a one-piece system, in which master, slave and tubing are installed together, but my son was able to get the individual parts for his 96.

[xj92]

I'm leaning towards thinking it's the master now too. Once I pull the master off, how can I tell if it's bad (other than just replacing it and seeing if it works :))? Any physical signs to look for?

[jjvande]

look for fluid on the fuse box or on the carpet under the master under the dash. I'm sharing your frustration...mine just started acting weird last week. syncros catch in 1st and 3rd. fluid leaking out of bellhousing...and i have to remove the tranny to get to the slave as well.

[xj92]

Been there done that with the leaking fluid from the slave. I already checked for fluid by the fuse box and everywhere else, and for fluid loss. No fluid loss and nothing leaking anywhere. Now that I've been paying attention more it seems the pattern is that if I haven't been driving it and it's cold, it'll sort of work and allow me to shift. After about 5-10 minutes of driving, 15 at the most, I lose it altogether and can't shift it at all. I'll be getting a new master today and putting it in to see it that's it. Hopefully so. I read in some other posts not to use the cheap AutoZone masters but that their expensive brand is good. True? Any recommendations overall for any other brand of master (preferably with lifetime warranty)? Or where to get it to save me a few phone calls on my break since I'm here at work.

[xj92]

Well, a week ago I put in the new master cylinder and vacuum bled it, and all was good. I had the firmest pedal feel ever and it worked great. Over the last week it's gotten worse and worse and is now almost right back to where it was in the beginning. I'm going to try bleeding it again tonight, anyone have any thoughts? Could the new master have gone bad already or did I never bleed it correctly to begin with? And if I never bled it correctly to begin with, why did the pedal feel and work awesome for a couple of days?

[jldiaz]

Have you been using fresh fluid? If not, it may have trapped some moisture that, on heating, evaporates anf forms bubbles - Like you hadn't bled it at all -

[5150xj]

I am having the exact same problem right now. I went ahead and replaced the slave and master cylinders. Bit it still does the same thing. The clutch is less than 1 year old. I currently have the pep boys master cylinder and I think thats the problem (hope). I am going to get a factory one and try it. If you find a cure for yours please post your findings.

Thanks

[truckeejeeper]

Please keep the info coming on this topic! I am having similar problems with my 91Sport. I believe I have the external slave. I bleed it and its good for a few days then slowly gets worse and worse, till clutch barely disengages and grinds. No leaks anywhere I can see. No fluid loss. Want to hear info on which slave/master to buy as well if i end up needing a new one...thanks ya'll

[xj92]

I vacuum bled it again last night and it feels great again, so we'll see if it lasts. I've been using new synthetic fluid this entire time, the system should be entirely flushed by now and the fluid coming out looks brand new. I also have no fluid loss.

[TUFFXJ]

Ha Ja It me Matt, I had this same issue when I did the convertion from the BA/10 to the AX-15. I pulled the tranny 4 times myself and I can to the following.

1. The Slave for some reason would allow air into the lines no matter what when it got hot. I even replaced it 2 times with a brand new unit (OEM)

2. It sucks!! (the internal slave that is

3. GO EXTERNAL it really isnt hard. You need a new fron retainer for tranny 40-90 bucks a new External setup 100 bucks online for OEM, New throw out barring and fulkrum pivot bar (spelling)? All can be had for 150-300 bucks depending on your sources and an afternoon to drop the tranny..I can help there I live less than a mile from yah and have a full shop

[xj92]

Hey Matt, I was traveling on vacation so I just read this. If this is the case, then I didn't need a new master cylinder :(. Any idea what would cause it to start? Because it was fine for the first 104K miles. I'll be driving the Jeep again tomorrow and we'll see if I lose pedal after another few days again. I'll have to learn more about the external vs. internal slave before I decide on that.

[Zoro]

Don't mean to hi-jack your thread but since we're on the subject of clutches I've got a question, why sometimes does my tranny grind a little bit while going into 2nd? I've read on here that other guys have had this problem too, at 179k the original clutch went so it's got 180k now with a brand new clutch...hi-jack disengage

[Zoro]

Forgot to add this, that's with the clutch all the way to the fire-wall

[TUFFXJ]

Forgot to add this, that's with the clutch all the way to the fire-wall

The AX-15 (if that is what you have) is infamous for 2nd gear being a PITA when cold. Try using synchromesh fluid it helps ALOT. Also it could just be the syncros going bad as well 2nd gear normally is the first to go. Ja I chased it for ever and I "think" it is a combo of the Slave rattling around and the lines getting a very small amount of air into the system. I also think that the fluid gets HOT as heck and boils in there sometimes and that causes the air in the system as well. Like I said I went to the external and have had no issues since. BTW we are getting a run for New years day going (the Gap or lower loop)

My gosh I sounded like an idiot in the above post. I wish spell check working on board posts ..lol

[MaXJohnson]

check the softline between the master & slave cyliners. It runs close to the #6 header tube. If it's not tied down, it can get too close to the header tube and the fluid will heat up and possibly boil. Over time the heat will cause the soft line to deteriorate to the point of failure.

[xj92]

I did a lot of work on the Jeep right before this started happening but I haven't been able to make a connection. I'll list what I did to it in the event that it might be useful.

Removed gas tank
Removed all exhaust components after the down pipe
removed the hitch & bumper
sleeved the frame rails all the way back
put the gas tank, hitch, & bumper back on
put on a new cat, glass pack, & tailpipe

The exhaust is routed the same as before, but with a much smaller profile now with the glasspack & smaller cat than before, so I don't believe the exhaust is closer to anything that might cause the fluid to boil, etc.

Edit: It took me so long to finish my reply that Max replied in that time. I'll check that line Max, since I loosened up some stuff when I replaced the master cylinder.

[5150xj]

Well, we, ryurabbit and myself, Finally figured out what was wrong with my clutch. After replacing the internal slave and replacing the master cylinder with 3 after market parts. I finally decided to go with the factory master cylinder. After we installed it we bleed about two cups full of fluid through it. Tried the pedal. Still was not right. So we decide to try to bleed it one more time before removing the transmission again. Thats when it happened. I pushed down on the pedal a couple of times and snap. The tab (for lack of a better word) on the clutch pedal where the master cylinder push rod attaches to it, Had apprently cracked from fatigue, and for the last month or more had been flexing back and fourth untill it broke last night. When it flexed it would not push the plunger in all the way so the clutch would not disengauge. Pulled the pedal out, welded it up, and now I have the best clutch that I have had in a lond time. Works perfect now. I have never heard of this happening before but then again I have over 277,000 miles on my '92. Hope this helps someone. Good luck.

[xj92]

I did start losing a little bit of pedal again. I didn't let go all the way this time, I zip-tied the line further away from the exhaust (it didn't seem super close, but who knows) and bled it again, now I'm just waiting again to see if this fixes it for good.

[xj92]

Lost the pedal again. It's gone back and forth from having a good pedal to none, and it's back at no pedal and I can't shift. Any other ideas? Could it be the internal slave cylinder at this point?