Unable to Get it in Gear 1990 XJ manual transmission Aisin tranny

About 6 months ago I had a new clutch Pressure plate and a release bearing installed. about 2 months ago I installed a new clutch master cylinder, everything was shifting quite well. Yesterday on my way to work I encountered some difficulty shifting out of first to second while going up hill, therefore I had to maintain that gear all the way up. Once I got to the top I was able to neutralize it and attempt to get it in other gears, it engaged 4th gear one time after lots of pumping on the clutch, when I took it out of 4th and attempted others it never engaged, and never re-engaged 4th. The peddle feels like it have a little pressure at the end of the depress, but not enough pressure to shift. :wantyou: I would appreciate any assistance or suggestions I may get. There is no noticable leaks, and the reservoir for the clutch master is full to the required line with fluid, did check during this ordeal.

Did you check the fluid level in the master cylinder? My internal slave bearing went bad inside my clutch and leaked all the fluid out the trans housing. Look around the bottom of the trans housing for any oil dripping. If there's no oil the problem might be inside the master cylinder.

I did check and found no leaks, I also checked the clutch Master reservoir found it full to required line with fluid. Thank you for your input

What gear oil is in the tranny? Chances are the synchros are shot due to Chrysler incorrectly recommending GL5 rated gear oil. GL5 eats the soft brass synchros in the Aisin Warner AX5 and AX15 trannies. Getting tougher and tougher to find used trannies not affected.

Install Redline MT90, it's a full synthetic and may just put off that rebuild for a while.

There may be air / moisture in the clutch hydraulics. Try bleeding the line.

I tried bleeding the line as you suggested yesterday, and was able to get some pressure after bleeding for some time. And was able to engage the gears, however, I allowed it to sit for like five minutes, when I returned I was back to square one. I then pumped the brakes up with a series of short strokes and then two high strokes and was able to get the pressure back which again only lasted a little while. What do you believe is the problem?

That hydraulic mechanism is marginal at best. Seems like the master cylinder barely has enough displacement to release the clutch. Here and in other forums you'll find writeups where folks have put in bigger master cylinders, I think it was something that fits late model Chevy pickups

Look at your present master cylinder and make sure it's not leaking out the back, because if it is it can run into the fuse box and that would not be good. Also if fluid is getting out air can get in - since you have to keep re-bleeding that could be the problem.

If you can bleed it and/or get it to pump up, then a few minutes later it won't work -- you have a leak. If the parts you had installed 6 months ago were not genuine Jeep factory parts, most likely your slave cylinder is shot. 6 months seems to be about the limit for the aftermarket clucth hydraulics. So many people have reported this that I refuse to use anything other than genuine factory parts for this.

Clutch MC air in system, whatever

About a month ago I changed everything new related to my clutch system. Changed the MC three times, am now running the Jeep MC. And still:

- I get normal shifting after sitting for approx. 8 hours
- hard shifting into 1st after about 30 minutes of driving
- Saturday the pedal went real spongy, soon returned to "normal"
- I bleed the system once or twice on the weekends because I have nothing better to do
- I am resigned to thinking shifting will never return to normal
- Occasionally I burn rubber to accelerate clutch failure

I have to agree with Eagle on this one. It sounds exactly like what happened to my slave cylinder. I also have a 90 XJ 4.0 5-speed manual. I am on my 4th slave. The previous 3 were replaced by my uncle who was the previous owner. I didnt have the cash to pay for the good stuff so I had to go with an AutoZone slave. It was put in a little over a year ago and its still working fine, but I dont think it will last too much longer, No signs ot symptoms yet, just gut feeling.

90red

What if you have moisture instead of air?
How did you bleed the system? Does your SC have a bleeding valve?