Had my 2006 super duty with a 5.4l engine parked for around 10 days. Started it up and had zero oil pressure and it knocks just like there is no oil. Oil level is fine and it ran perfect before it sat for a little while. Any ideas about what it could be. There is 180,000 km on it. Oil has 3000km's on it. I changed the oil filter thinking it might be plugged but no difference.

 

Shot in the dark here: I have seen a 5.4 3 valve engine do this once before. For absolutely no oil pressure, sounds like a crank thrust bearing may have fell off the crank and now the crank walks freely back and forth and is losing oil pressure. Maybe a sludged oil sump too.

How often is the oil changed? Is it clean?

 

I change the oil every 6000km's usually. The oil is no more dirty than it usually is. Might try pulling the pan off to take a look and see

 

Most likely would be the best thing to do. I'm not 100% positive that is what it is, but I really can't think of anything else to make such a sudden issue. If the crank thrust bearing did come apart - you should see some metal pieces or shavings laying in the pan. Might even cut open the old oil filter (if you still have it but you probably don't) for metal shavings inside of it. Run a magnet over the pleats and if you find a lot of shiny flakes and it sticks to the magnet, most likely main bearing material.

 

Thanks for the info and help. It is fixed for now and seems to be working fine. I changed the filter and dumped the oil. Filled the oil pan with 5l of diesel along with a litre of tranny fluid and seafoam. Let it sit for 24hrs the started briefly for 10 seconds. Took about that for the oil pressure to jump up. Then ran for around another 10 seconds. Dumped the oil pan and filter filled with new oil and started. Oil pressure is right where it should be. Going to drive for a week and change again. Hopefully this has worked and no more issues. Thanks again.

 

No problem. Glad I could help. Sounds like a sludge issue. Sump is probably plugged. If that is the case; that's way better than a failed thrust bearing!