Looking to get some advice. Sounds like tappets or ??
It is only on the passenger side. Sounds like it is towards the back of the engine.

1995 discovery engine noise - YouTube

 

Would do an oil PSI test cold and hot, idle and 2500 rpm and post numbers. Would not drive truck. Would look at https://landroverforums.com/forum/di...-repair-37551/ and https://landroverforums.com/forum/di...estions-46975/ for low loss filter. If running 10W30, switch to 15W40 Shell Rotella. Maybe as part of the procees a quick oil flush product. You can also listen along the valve cover with a stick or long screw driver touched to ear and cover, should be able to localize sound.

 

I do not have the tool to do a oil pressure test. I have already put on the high capacity oil filter and installed rotella 15w40 oil, I have also added the Lucas oil additive. Does anyone in Colorado have the oil pressure tool?

 

Sounds like an exhaust leak to me. I'd replace manifold to downpipe gaskets as well as Y-pipe and check the welds on y-pipe for cracks and black soot

 

There is a Harbor Freight in Littleton.

Map

There you can buy this (pic is the link).

 

This would be where I apologize for not giving enough information.

Last summer I did the head gaskets including all the exhaust gaskets. I did find my exhaust bolts a tad loose but not enough to give off a false tick sound. They have since been torqued. 3 weeks ago I did the downpipe exhaust gaskets in hopes that was the noise. After that had no effect I stethoscoped the passenger head and the closer i got to the rear the louder it got.

 

Has anyone used that kit on a disco? I only ask as I bought the coolant pressure test kit and it did not have the right adapter for my disco.

 

I used it on mine. The adapter in the kit that fits the port on the disco is a teensy bit too small. However getting it nice and snug, but not over tight, everything worked ok.

 

Good enough for me. Going to go pick one up today.

 

I think it's a bomb. Go to the airport and have TSA check it out.