I recently did the oil pump, timing chain and sprocket replacement, oil pickup screen cleaning, and crux seals on my 1998 Disco 1 and now it has a engine tick which sounds like a lifter. The vehicle gained oil pressure upon start up and the light quickly went away so I believe it's getting oil to the rockers. This was my third oil pump replacement on these vehicles so I am familiar with the scope and the installation seemed to go fine. I'm curious if I messed up the camshaft or it got slightly out of time somehow. Any thoughts before I tear it down again? I've attached a video to hear the noise.

 

Could not hear the tick from video. Maybe get the fan clutch to slip first before taking another, or even better remove the serp belt and video a few seconds to eliminate other noises.

Count the ticks for 6 seconds, multiply by 10. If result is nearly 1/2 engine RPM, then likely valve train related. If equal to engine RPM, the related to crank.

My '96 has a lifter tick that goes away about a minute after starting the engine. Not recommended to add thick or honey-like oil additives, because they can mess with the lifters.

 

The ticking could be from a slight timing issue, even if oil pressure seems fine. Double-check the camshaft timing, and make sure all timing components are tight.
If oil flow is good, the issue might be with the lifters or valve train. Check those areas before tearing it down again!