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Hydraulic clutch issues


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So for the last few weeks, my MJ has been getting noticably harder to shift. Until the other day when I pretty much lost the clutch completely. So I attempted bleeding the system, no dice. So praying that the internal slave didnt go out, I replaced the not leaky 5-month old master cylinder, and again... no clutch. After excessivly bleeding it, the clutch engagement was exactly as it was before I installed the master, so I don't think the master was the issue.

 

So I'm left with replacing the dreaded internal slave :ack: But I was hoping you guys could check me. I have always had black colored fluid in the master, even after I put the new master in. Now I can start the jeep up with the clutch pedal down, and in first gear. While stationary I can't move into any gears, but I can take off in first. Sometimes there is some "dragging" as the clutch is not fully disengaged while at a stop. And NO I AM NOT DRIVING IT, I had to get it home, so I drove it without using the clutch.

 

I really need to get this fixed, but have limited funds, and this is my dd... Last friday my mustang became inoperable so I can't drive that. And since I am a full time student, with a part time job I never have full days off, so replacing the slave will mean me lying in my driveway until god-knows-how-late until I get this fixed. So obviously I don't want to do this if not absolutely necessary.

 

 

Thanks guys

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Sadly, it probably is the slave, but there are a couple of things to verify first.

 

1) How are you bleeding the clutch? I've seen people (including some who REALLY should know better) try to bleed the clutch by pumping the peddle madly while the bleeder is open. All this does is foam up the fluid. It's a two man job, and it requires patience to do it by the book.

 

2) There is a third component that can cause loss of pressure, and that's the line/hose assembly between the master and slave. I had one blow out at a toll booth in the Massachusetts Turnpike when I was 100 miles from home. That was a looooooong drive with no clutch. Both ends are metal, but the middle portion is rubber, like a brake flex hose, and it can crack. The good news is that you can crawl under the vehicle and look for wetness pretty easily.

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I was bleeding it properly, one person depressing the pedal, then I open the screw...

If you are doing it exactly as you wrote, that is not correct. The correct procedure is for the wrench man to open the bleeder, then the peddle man SLOWLY depresses the pedal. When the peddle hits bottom, it is held there until the wrench man closes the bleeder, and only then is the peddle released. Once the peddle has come back up, it can be pumped once or twice (again, SLOWLY) with the bleeder closed, the peddle is then brought back to the top, and the sequence is repeated.

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in lieu of preventing crappy master to slave lines can one not just purchase a length of brake line and curve it appropriately with a little coiley to give it some spring and thus making a more reliable line?

Define what you mean by "crappy." The clutch hose I blew was in my '88 Cherokee. IIRC, it blew in 2002 (might have been 2003), so the vehicle was at that time at least 14 years old and had well over 200,000 miles on it. It was my fault -- I had replaced the clutch, master and slave a year or two previous (at 204,000 miles), but didn't think to replace the hose.

 

Yes, you can do as you suggest. You could do the same thing for the flex hoses serving the front and rear brakes. Same type of hose. Do you consider those to be "crappy," too, simply because they are flex hoses rather than a coiled metal tube all the way?

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The actual term according to the other guy is the throwout bearing unit. Slave cylinder were used in 1984 to 1986 XJs and MJs. 1987 to 2001, the bell housing was redesigned and the internal throwout bearing unit replaced the slave cylinder to accomodate the 4.0L inline 6 as well as the 2.5L inline 4. Continue to manually bleed your throwout unit until pressure builds out and the clutch pedal is firm. Use the steps on the repair manual and/or Alldata, if you have one. I suggest go t to your school auto shop and print out some steps regarding clutch bleeding. When in doubt, replace the internal throwout bearing, but also check your clutch to see if any damages on it from your no-clutch driving. I'm also doing the same thing on my 1986 Jeep Comanche because of a defective slave cylinder from my unsuccessful bleeding. By the way, also check your clutch lining from your master cylinder to the internal throwout bearing. By doing so, you need to drain the fluids and loosen the fittings ends at the lining ( you will need a line wrench to do this). To test, use a high pressure air nozzle and put at the end of the lining and blow all the rest of the residue from the fluid and make sure the other side of the lining is secured and not pointing at yourself or anyone. Again, squeeze the air nozzle and use your other hand or helper to use his hand to see if any particles may be present. Also, check the rubber hose part of the lining for any leaks or deforming when applying air from the air nozzle. If none are present, then your linings are okay. This will lead you to the defective internal throwout bearing. When installing the new one, make sure the ends are tighten correctly by your line wrench to ensure no leaks in the future. This is one of the mistakes I've done which led me to the defective slave and master cylinder. The clutch itself was okay and the fork is not damaged.

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Lucky that my clutch itself wasn't damaged and so as the fork itself to the throwout bearing. Okay, I wish you luck in getting your 1989 Comanche clutch repair. You're doing a great job and my last advice, don't give up. Wish me luck as well as I'm hopting that my clutch will finally will release, after a long proceedure of clutch bleeding. Allrighty? Happy Jeeping on your Jeep MJ Comanche. Beepbeep!!!!

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