Front valve cover breather
 

I was just wondering if there is any reason i can't just put a small cone air filter on the front valve cover breather? right now i have a little oil blowing back through. I replaced everything involving the PCV blow by problem. Its just a small amount of oil. Any problems with this?

I would leave it alone as long as the elbow is not cracked.. I put a small breather in place due to my elbow cracking and leaking everywhere.... The blow by as long as its not extremely excessive is normal for the most part...

The hose that goes to your intake in combination with your PCV valve and vacuum tube on the back of the valve cover help balance pressure in your crankcase. This helps to reduce blowby. If you're getting oil coming out of the end that you want to put a breather on, make sure the other hose is drawing air via intake/throttle body. Fresh air in the front, crankcase gases out the back.

To answer your question: Yes it is okay. Many XJ owners do this mod. What many fail to realize is that the intake tube going to the throttle body creates vacuum on the fresh air tube also, cause some oil to be drawn back, despite everything in the CCV system working fine.

Installation of a small cone filter should reduce or eliminate any oil, as fresh air is drawn in from the engine compartment and not from the filter side of the airbox where there is throttle body vacuum.