JK manual transmission issue

[junkxj]

I bought a 07 jk, 159k miles, last week that has a transmission issue that has me stumped.
With the engine off, it goes through all the gears perfectly. With the engine running, but the vehicle stopped, same thing, trans feels perfect. While driving, the trans is hard to get into gear at times, but at times not. Pumping the clutch or double clutching makes no difference. No scraping noises like bad syncros. I checked the master and slave cylinders, no leaks. The clutch feels perfect. I changed the trans fluid, no change. It will go into any gear, but takes excessive force at times.

Any ideas, thoughts??

 

[Fabrik8]

Sounds like a shifter/linkage bushing problem. They can create problems under certain conditions of vibration, load, temperature, etc., that move things around just enough to create linkage alignment/travel problems. I'm just speculating, as I don't know the specifics of Jeep transmissions, but the symptoms sound somewhat generic as a shifter or linkage issue. Specifically check the ball or bushing at the end of the shift lever. It's got enough mileage for things like that to happen and get sloppy.

I don't know how sensitive that transmission is to fluid type, but that may be worth a look as well. Some manual trans are quite sensitive to fluid when it comes to shift quality. Else maybe a subtle clutch/throwout problem. The fact that it only seems to have a problem while all geared shafts are rotating (while driving) is likely a clue.

 

[junkxj]

Sounds like a shifter/linkage bushing problem. They can create problems under certain conditions of vibration, load, temperature, etc., that move things around just enough to create linkage alignment/travel problems. I'm just speculating, as I don't know the specifics of Jeep transmissions, but the symptoms sound somewhat generic as a shifter or linkage issue. Specifically check the ball or bushing at the end of the shift lever. It's got enough mileage for things like that to happen and get sloppy.

I don't know how sensitive that transmission is to fluid type, but that may be worth a look as well. Some manual trans are quite sensitive to fluid when it comes to shift quality. Else maybe a subtle clutch/throwout problem. The fact that it only seems to have a problem while all geared shafts are rotating (while driving) is likely a clue.

Good call, I will pull the shifter tomorrow and see what that bushing looks like.

The new fluid I put in it is pennzoil Synchromax, which is what it seems most people run in these trans.

What has me stumped is the internment aspect of the issue.

Thank you for the thoughts and info.