jeepcoma Posted December 31, 2009 Share Posted December 31, 2009 My wife was driving the MJ (4.0, AX-15, internal slave) this morning and the clutch completely jammed up on her. She couldn't push it in at all to change gears or anything and managed to limp home in 1st. I get home from work and it's frozen up solid. She said it's randomly happened to her before, it would get real hard and be impossible to push in, but after a second or two it would free up and act completely normal. Any idea what can cause this? I looked in the cabin and there's nothing obstructing the pedal movement, what about beyond the firewall? Could something have gotten in the way in the engine bay, where the rod extends past the firewall (I can't really see it from the top and of course it's dark and cold out)? If there is water in the clutch fluid, could it have frozen from the cold snap we've had? A few small frozen particles of water floating around maybe clogging something? Any tips where I should look first? Despite having driven manuals all my life I've never had to actually do any maintenance on them and am a complete newb... Link to comment Share on other sites More sharing options...
freakjeep93 Posted December 31, 2009 Share Posted December 31, 2009 man ive never heared of anything like that ever happening. i wouldnt even know where to start. :dunno: but good luck fixing it. :thumbsup: Link to comment Share on other sites More sharing options...
jeepcoma Posted December 31, 2009 Author Share Posted December 31, 2009 Wife just got back in, she said the previous times when it happened, the temp was well above freezing, so it seems frozen water in the line might not be so likely... :dunno: Supposed to take the truck to Boston tomorrow to stay with a friend for new year's :fs1: Of course the MJ craps out now. Link to comment Share on other sites More sharing options...
Wildman Posted December 31, 2009 Share Posted December 31, 2009 Yes, it's possible that the brake fluid that's used in the clutch master, DOT 3, Which is glycol based, has adsorbed water, and "froze". Is there anyway you can get a heat gun, or even a hair dryer in there to hit the master and the line with some heat??? Once you get it thawed out, it might be a real good idea to flush out the old (20 year old) fluid, and replace it with DOT 5, that's silicone based. Link to comment Share on other sites More sharing options...
jeepcoma Posted December 31, 2009 Author Share Posted December 31, 2009 I thought of using heat but the fact that it "froze" randomly in the summer as well confuses me. It's also useful that this intermittent problem is currently faulting, meaning maybe I can see exactly what the problem because I can see what's gone wrong. If I just wave a heat gun around under there and it goes away, it's just another intermittent problem. I flushed the fluid earlier this summer, I was hoping to fix a chatter problem I was having after extended driving. After driving for some time (less time in the heat of summer), the clutch would chatter when trying to move from a stand-still, I also kinda thought that might have been water in the line. Flushing didn't seem to make any difference to the chattering problem. Neither of us can remember if the "freezing" problem first happened before or after the flush. Some other things I've found: FROZEN CLUTCH.-When a clutch fails to disengage, it is frozen. Failure of the clutch to disengage may be caused by a defective clutch mechanism or by water absorbed in the material that lines the clutch plates. When a clutch becomes frozen, inspect the operating mechanism. Check the control rods for obstructions or loose connections, and check for excessive clearances in the throw-out bearing pressure plate, the pivots, and the toggles. In a twin-disk clutch, warped disks will cause the clutch to freeze. (Warped disks are caused by extended running in neutral position.) If a clutch has molded clutch linings, moisture will cause the linings to swell and become soft. When this occurs, many linings tend to stick to the mating surfaces. Every effort should be made to prevent moisture from getting to the clutch linings. If a molded lining becomes wet, let it dry in the disengaged position. Allowing the linings to dry in the engaged position increases the possibility of sticking. can someone tell me why a frozen clutch occurs and how to fix it? i have never heard of this before thanksGo to the top of the page ... Like just generally speaking? The throwout bearing rides on a collar (a tube around the trans input shaft), and with enough rust or corrosion it can get stuck. If the throwout bearing can't move it will give the impression the clutch is frozen. If your clutch pedal is hard and won't move that would be my guess. You would have to remove the trans and free it up, and re assemble after it was greased properly. Link to comment Share on other sites More sharing options...
Wildman Posted December 31, 2009 Share Posted December 31, 2009 The "chattering" you speak of is generally caused by "hot" spots on the flywheel. The only way to correct that problem is to replace the flywheel with a New (not resurfaced) flywheel. Yes, I thought of the slave cyl being defective, or the "finger" on the pressure plate could be bent, or damaged/wore out. Now many miles do you have on this truck???? With you having prior problems this past summer, and now, it just might be time to replace the clutch/pressure plate, slave, and flywheel :dunno: Link to comment Share on other sites More sharing options...
jimoshel Posted December 31, 2009 Share Posted December 31, 2009 I believe the first thing I would do is loosen the line between the master and slave cyls.This would indicate whether the prob is mstr cyl or clutch assy. Wrap a rag around the line to catch fluid.The pedal moves prob is clutch assy. Pedal still doesn't move, master cyl. Link to comment Share on other sites More sharing options...
jeepcoma Posted December 31, 2009 Author Share Posted December 31, 2009 Just went out with the wife and the flashlight to poke around and see if anything was obviously wrong. The clutch was still stuck, and I noticed the reservoir mounted to the firewall flexed when she applied pressure. Eventually it just went to the floor like nothing was ever wrong. I took the cap off and the level was good, and had her pump the pedal slowly while I looked at the fluid. There was never any movement in the fluid whether it was sticking or moving smoothly, so I put the cap back on and tried the pedal myself. I'll try flushing the fluid again tomorrow after work. With the engine off (hasn't been running since this morning) It seems to have three distinct modes: completely frozen, normal operation, or hard pedal that moves with a distinct "click/clunck/tap" noise after about half-way travel. It really feels as if it's a mechanical obstruction, like something is flopping in the way and either holding it up completely or partially blocking the way and then getting suddenly getting forced out of the way. The pedal will just work like normal for four or five pumps, and then stick, and then just as suddenly work normal again. Putting the tranny into or out of gear or rowing through the gears didn't seem to make a difference. I looked at the linkage I could see from under the dash, nothing seemed to be blocking anything. I replaced the little retainer (brain fart and can't remember the name, it looks like a bobby pin and you stick it up to the "eye" and then bend the ends) just in case it was binding on anything (it wasn't). Can that plastic linkage be binding up any anything? Is there a diagram anyone has of the pedal linkage, so I can get an idea of what's going on fast where that rod disappears into the firewall? Link to comment Share on other sites More sharing options...
Geonovast Posted December 31, 2009 Share Posted December 31, 2009 The throwout bearing rides on a collar (a tube around the trans input shaft), and with enough rust or corrosion it can get stuck. If the throwout bearing can't move it will give the impression the clutch is frozen. Not true with our internal slaves. Link to comment Share on other sites More sharing options...
jeepcoma Posted January 2, 2010 Author Share Posted January 2, 2010 I flushed all the old fluid out with a brand new bottle of DOT3, it made no difference to the sticking problem. However I did discover that if I do not take my foot off the clutch but instead leave it depressed about 1/4" or so (not enough to ride the clutch, just to keep pressure on the pedal) that it never gets stuck. As soon as I take my foot off though, it sticks. It's no longer just rock hard either, it will push in with a lot of resistance and then "click" and work like normal again until I take my foot off the clutch. It feels like a mechanical binding, but I'm not sure how to figure out where without throwing money at it. And of course this could have happened at any time during the summer and I wouldn't have cared, since it's my winter vehicle, but of course it has to happen now when it's snowing all the time and I can't get anywhere without the Jeep. I'm thinking (hoping) it's just the clutch master cylinder that's worn out? If I look at the master from the engine bay, I can see it flexing left and right and loud noises from it. I know I should replace the slave cylinder at the same time, but it's internal and I do not want to remove the transmission at this point in time to do it: a quick fix now would suffice to get me through the winter and I can fix it the right way when I'm not lying in a snow drift to do it. Link to comment Share on other sites More sharing options...
james750 Posted January 2, 2010 Share Posted January 2, 2010 I vote throwout bearing... Link to comment Share on other sites More sharing options...
freakjeep93 Posted January 2, 2010 Share Posted January 2, 2010 :agree: sounds like a rusted up r bad throw out bearing Link to comment Share on other sites More sharing options...
Dave Stark Posted January 2, 2010 Share Posted January 2, 2010 This sounds very familiar to what mine is doing. When i drive in heavy traffic & have to use the clutch frequently, it gets very stiff, but if i let it rest for a few minutes it goes back to normal. Link to comment Share on other sites More sharing options...
mnkyboy Posted January 2, 2010 Share Posted January 2, 2010 mine did something similiar. From the time i got the truck i noticed a small "pop" when i pushed the clutch,on my way to work one morning i went to push it at a light and it popped then locked up on me. I limped it to work and had a new master cyl sent to the shop,when i took the old one apart i noticed the spring had been broken and was causing the popping sound.the spring pieces got jammed in there causing the lock up. Link to comment Share on other sites More sharing options...
avnsteve Posted January 3, 2010 Share Posted January 3, 2010 sure sounds like the master cylinder has failed, the piston is hanging up in the cylinder... Link to comment Share on other sites More sharing options...
jeepcoma Posted January 3, 2010 Author Share Posted January 3, 2010 Guess I'll find out if it's the MC or not, just ordered a new one from rockauto. Seems like a logical first step, if it fixes the problem I don't need to spend any money on unnecessary parts and the time to put them in. If it doesn't fix it, I'll bite the bullet and replace pretty much everything else, since I'll only want to do the job once. Link to comment Share on other sites More sharing options...
mnkyboy Posted January 3, 2010 Share Posted January 3, 2010 Thats the easiest place to start. last one cost me $30 and took 20 min to install Link to comment Share on other sites More sharing options...
jeepcoma Posted January 9, 2010 Author Share Posted January 9, 2010 And the winner is... DING DING DING the master cylinder!! As soon as I got the replacement I knew the old one just wasn't right, but I never had anything to compare it to before so I simply didn't know. I removed the old plastic piece of crap and it was completely buggered up. I'll go get some pictures later and put them in my build thread. Feels like a new truck now. I got the Rhinopac master cylinder from RockAuto, $30 bucks shipped. Link to comment Share on other sites More sharing options...
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