i have a 2004 dodge 5.7 hemi with 97k miles on it and i hear this ticking sound/ knocking sound. it only gets louder when the RPM's are up, their is no vibrations in the truck or in the wheel. oh and if it helps when im really getting on the gas my oil pressure gauge says i have no pressure but once i turn the truck off and turn it on it works fine again like nothing happen, but if im driving normal the gauge doesnt go down and nor any engine lights come up. i took it back to the dealership to get them to fix it and they said it was the lifters so they "say" they replaced them and gave me back my truck and it was fine til bout 5 miles down the road then the noise came back. i love dodge but i just would like this noise to stop please help.

 

Common problem called Hemi Tick. Please do a search and you'll see many others have the same problem. It's not the lifters, it's the valve guides.
Look HERE for other common problems including Hemi Tick

Mine has done it since new, but I refuse to have them tear apart my new truck with less than 10kmi on it. For that, I'll deal with the slight noise.