I've searched and can't find a thread that exactly matches what I'm looking for so here we go......

I have this thump that keeps time with the engine. Sometimes it goes away but its almost always there.

Its behind the radio/glovebox. I can't hear it from the engine bay or on the ground below the tranny/oil pan. It is slow with Idle and picks up with the rpms at a steady pace. When the engine is loud you can't hear it anymore and I can't feel/hear it with the screwdriver trick when I touch it to the engine.

I thought it might be something with the flex plate but I thought that noise was near the inspection plate at the bottom of the tranny.

 

Ah ha! I have two xj's one a 95 the other a 92 both have a 4.0 HO and both of them make the same sound ive been told by some that this is typical of the strait six. My first impression was that it was the lifter's but later relised it is coming from the wrong part of the engine.....so I have know idea. could be nothing or maybe we are all driving rolling death buggies.

I love my death buggie