engine knocking top of engine as it warms up its not so load

Gregory Carlson  we would need to know the exact year, model and size of the engine. The knocking could be unrelated to your oil pressure. Of course, you do want to check it with a proper gauge. Also, make sure you changed the oil, filter etc and checked your oil level. After that do a compression test and a leakdown test. Let us know what you get on those.