Hello All; Funny thing that this discussion about the oil pump screen came up just after I was reading about engine oiling systems in my new car book. Apparently if the oil pump pickup screen gets clogged or blocked in most modern engines, the oil pump will draw oil directly from the crank case through a bypass. I would check the oil level, and if sufficient, drop the pan and check the oil pump itself. My thinking is that your oil pump might be worn out since the lifters only tick after the engine is warmed up and the oil thins out. Best Of Luck Best Regards Arran Foster 1954 Imperial Newport Needing A Left Side Taillight Bezel and other trim parts.