Originally Posted by sdhow

Uh...lifter tap. Yeah. This is very likely NOT a lifter tap. When you have a oil pump failure, overheating often occurs, causing the well-known "tick"...at hot idle. The only way to correctly diagnose this is to pull the heads and verify if you have a slipping cylinder liner. It doesn't take much to free up a liner and have it smacking the head, leaving the liner's imprint in the head gasket and head itself. This seems to be very common on the 4.6L engines of '03 and '04, as LR used a different retaining compound and removed the oil coolers, allowing the engines to run hotter to meet the lower emission standards.

The "fix"? Pin the liners to the block or install a new short block with "top hat" liners...about $8-10K. Otherwise, live with the "tick" until she blows. How many miles does she have on her? Oh, and when you had the oil pan off, did you check the rod and main bearings?