Sounds like lifter noise from the back of the engine in the valve cover area when the engine is warmed up. Not sure how to diagnose a lifter, will dig into this deeper. If it is a lifter, replace them all on the stock cam? I've read that some 4.0s have lifter bores large enough to pull lifters w/o pulling head. All the bad luck I've had on this thing, maybe I'm due for some good luck. Also, would it be worth swapping in a new, more performance oriented cam at the same time? Not looking for a lumpy idle, just a minor improvement if I have to swap it anyways. 1990 4.0l daily driver status. I have another vehicle if this one needs to be laid up for a week or so for repairs.

 

FYI, only on the 2.46 four cylinder could you remove and replace the lifters without removing the head.

 

Damn. I really don't want to pull the head.