Engine Mechanical problem
1988 Chevy Blazer 6 cyl Four Wheel Drive Automatic 165000 miles

my oil pressure dropped all the way down and before it did that i noticed that it was fluctuating a little bit. So my hunch is that I have a bad oil pump. I am wondering if a faulty oil pump would cause knocking noise. What do you think?

If your oil pump is bad and there is a lack of oil pressure the engine will make all kinds of noise to let you know that it is unhappy. You would first hear like clicking or lifter noise then it deepen to a lower end knock then eventually seaze up and be done. Now if you didn't hear any noise then you need to put a guage on it and see what the pressure really is. Now if the engine has been rebuilt recently it may be the oil pump pick up came off. This happens alot as they forget to red lock tite it or spot weld it to the pump. What I do is red lock tight it. First I put the pump on and then put the screen in so I can move it then I put a 5/16 nut on it and put the pan on with out the gasket this gives me clearence then I mark the pump and the screen so I know where to put it then red lock tite and put it in place have never had one fall off.