My Chev. Cavalier is knocking,so I pull off the overhead cam cover and I cranked the engine over a few times and I am not getting any oil up at all on the rocker arms.Does that mean I possibly need a new oil pump,since the car was driven low on oil.Could it possibly burned the pump out.I've never changed an oil pump in a vehicle newer than a 1984,am I possibly taking on a harder task then I forsee.