Not a good idea. There is crankcase pressure in the valve cover that has to be released, hence the CCV system. You would probably have oil blow out some where. I had this happen on another vehicle in my youth. I replaced mine a while back and those grommets were a ***** to get out.Broke one of the elbows as well. I got a replacement elbow at Advance Auto. The elbows are different , so make sure you get the right one. I believe they have the grommets as well. Good luck.
'97 XJ Moss Green Metallic. 2DR. 2WD AW4 tow pkg.,3.73 gears. Firestone Destination A/T 225/75x15.