Re: may have a problem (oil pressure)
Assuming youchecked the oil, and accepting that the oil pressure gauge could be faulty, there is still the problem with "a kind of a knock".
My friend once thought he was doing a good thing when he installed a large dia. YJ filter on his 258 CJ. He took it out for some hard wheeling and the motor mount poked a hole in the filter. Not being a real motorhead he happily thrashed his CJ until it ran out of oil and developed "a kind of a knock". Not having any oil with him he drove it home. Needless to say that "a kind of a knock" did not go away. It sounded like someone was beating on the block with a sledge. OOOOps
Noises from an engine tell you something. Pinpoint the noise. Put your ear to a long screwdriver and touch the tip to parts of the engine. Bottom end noises are not good.
Worst case is an engine rebuild, but after you get over "cash output shock", you'll be real happy for a long time with a fresh engine.
Funny thing is, the more I practice, the luckier I get