Forms with Ford Econoline help please

Hello everyone on the forum. I have a problem with a 1998 Ford Econoline with a 4.2L V6 engine. Water recently got into the engine, so we only replaced the lifter valve gasket because the head gasket wasn't damaged. We did several tests to find where the water was getting in, and we finally reassembled everything. But now there's a problem with the oil pump. It seems like the oil isn't reaching the lifters; there's very little pressure. We start it and let it run for about 10 minutes, and the oil pressure gauge drops and the oil light comes on. My question is, is the pump damaged? Will I have to replace it, or what could be causing this problem? Please help.

Remove the valve cover and check that it has oil; perhaps the gasket was installed backwards. Alternatively, remove the oil pressure sensor and have someone start the engine and check how strong the pressure is. If you have the instrument, even better.

Okay, we tested the oil pressure sensor and it wasn't building pressure. We removed the pump again, refilled it with a little more oil, and reinstalled it. It worked; the needle rose and the oil light went off. But as I mentioned, after 10 minutes the pressure dropped again and the light came back on. On another note, I was checking the manual for a Ford Expedition engine, which is very similar to the Econoline's, and it says that if the pump is worn, it should be replaced if there's a maximum gap of 0.0016 inches between the pump gears and the housing. But I'm told that when I replace the pump, I also have to replace the timing chain cover. What should I do? Help!

Add some Lucas oil and let it run a little longer so the oil level rises more. Good luck. I hope this helps.

I would also suggest you add a physical marker, as the original bulbs are often inaccurate. Even if it's just to verify.