I have a 95 F150 that loses all oil pressure and makes a terrible knocking sound. If you shut the truck off it will run fine for a few miles then lose oil pressure again. If I change the oil this doesn't happen for awhile. Sometimes it will go weeks and at other times just days.. What should I do?
Here is some info on the truck
The engine is a 5.0 V8, and yes the oil is changed frequently. Yes we live in the "rust belt"missouri and no I don't have the history. Mileage 175000, The cap is clean. Thanks for trying to help me

 

I assuming when you change the oil you change the filter, right? (I expect so, everyone does, but I just want to rule it out right away)

If that's not it, (and I expect it isn't) then a couple of questions if I may:

-what engine?
-what mileage
-is your truck from the 'rust belt'?
-do you have a maintenance history? (IE is there any indication the previous owner may have never changed the oil?)
-if you are tall enough to do so, (my wife is only 5' and can't do this) remove the oil filler cap and look inside. Do you see black, nasty stuff or is it pretty clean?

I am suspecting either an engine that is just plum wore out, or a clogged filter screen on the oil pump (also called an oil pickup strainer).

The second MAY be (relatively) easy-- I know on the straight six you can remove the pan without removing the engine but don't know about the v8.

more info would help diagnose.

 

Yup, need to know the engine, either a 300 (4.9L) I6, 302 (5.0L) V8, or a 351 (5.8L) V8.

Prolly gonna have to open up the bottom end by removing the oil pan. The V8's need to be lifted out a few inches to make enough room. Not a big deal but just adds some labor.

Yeah, need to know the milage too.

Adrianspeeder

 

Sounds like there's something blocking the pickup screen, maybe some piece of crud in the pan.