I have a 99 F150 4.2 w 172000 miles on it and the oil pressure gauge just dropped out about 2 weeks ago. I pulled the oil pump (it's exterior) drained the oil and put a couple of gallons of diesel in the pan thinking it may have picked up some sludge. Let it set 2 days and drained it. Filled it with new oil and filter and started it up. Still no oil pressure. So I removed the new filter (no oil in filter) and drained the oil and removed the timing cover today. There is a valve installed in the timing cover that allows the oil to bypass the filter and I was going to replace that. What I found was that the gear running the oil pump rod was stripped and the gear on the front of the timing gear was badly wore. My question is when I start putting this back together does the timing have to be set a tdc for the sensor to pick it up correctly or will it do that by itself. Thanks in advance.