Diagnosing Jeep 4.0L Engine Noise

 Tapping or knocking?    

1. If noise is higher pitching tapping, your likely to find:
   1. Stuck Lifter
   2. Loose Rocker Arms
   3. Clogged oil passage in the rod
   4. worn Cam lobes
2. Lower pitch knocking
   1. crank bearings
   2. If noise is in the back and around the transmission, check for cracked Flexplate

Related Videos:
 

1. 2001 Jeep Grand Cherokee Engine Noise (4.0L) - EricTheCarGuy
   http://www.youtube.com/watch?v=B9DP7jhX9XU
   1. has tips on how to RnR Valve Cover
   2. checking oil delivery
   3. tightening rockers

 
Additional suggestions or experience?