Don't know if you have an auto or manual trans but....
On the transmission is a vent hose that attaches to the top of the trans and the end with the vent is tied to the firewall or filler tube (if auto trans). The t-case also has a vent hose but on some years it just lays on top of the transmission (that's where mine was on my 03 auto). If that happens to be your t-case vent, extend it so the vent cap is high up in the engine bay.
Fill in your profile and tell us about your TJ. We can give better answers when we know what you have.
Silence is Golden, Duct tape comes in Many Colors.
Journeyman Meterman IBEW Local 611
Work with enthusiasm as though you were working for the Lord rather than for man.
Siena Jeep Owner's