I have a 2001 Explorer with the 5.0L engine. It has low oil pressure when it gets warm... like 20 minutes into driving, not when water gets to temperature. I have a noise at 1/2 engine rpm frequency. It is not main bearing noise - I know that one. Sonds to me like it comes from the passanger side of the engine - where oil pump shaft is?
I have added a mechanical oil pressure gauge with a "T" - pressure shown at idle starts at 40-50 PSI at cold and drops to a pulsating 5 PSI after 30 minutes of drive. The dummy gauge in the dash pulsate too at that point (sender it's just a pressure switch - a new one) so the pressure is real.
Changed the T-Stat because temperature readings with the scanner where higher (212F) and I was thinking that the oil gets to thin - now I have 180F. No change.
Changed oil pump in a shop. He said he put new oil pump, strainer, and shaft. Nothing changed. Chaged the Syncronizer myself because it looked like the 1/4" hex (that engages the oil pump shaft) was worn out. A little better, but still not enough. Runned some Seafoam and AutoRX in the engine to clean the passages. No change...
The noise is gone when I press the gas pedal even a little. Oil pressure raises, but I think is not that - if I coast I have 1000 rpm, 10 PSI and noise. I press easy the gas - I have some 9 PSI and no noise. It's like I take some "play" out.
I can post a video with the noise and pressure eventually.

Had any body some ideas about what to check?

 

what weight oil?
how many miles on the motor?
rebuilt or not?

the later motors are designed to run at ~210* for emissions / fuel mileage reasons / sludge control.

 

I bought the car recently. Initially I didn't hear nothing suspect, then a little noise came up. I changed the oil to 5W20, like is in the book. Bad. Changed to 5W30 - still bad, slighty higher. I did run a while with Diesel 5W40 and the was a little better, but still would drop below 10 PSI. All in all, when something warms up, it doesn't matter what is inside, pressure drops like a rock. I don't know what the previous owner had inside - maybe pure lucas to sell it...
Engine is at 92k. Looks original - it had the original spark plugs, that Motorcraft doesn't carry anymore. I did go lower on temp hoping to help the oil thikness. I could go back to 192 but I have biger fish to fry now
The noise sounds like it is at 1/2 of engine revs. Could it be the new pump bad too? Lifters? What else could "shift" inside with engine the load, because the noise is louder on coasting or at stop light - no gas pedal pressed. Now I keep it in N at stop to help the pressure.

 

describe the noise..

clunking?
pinging?
metallic?
solid?
hollow?

where does it sound like it's comming from?

driver side
passenger side
top of motor
bottom of motor

what RPM?
accelerating?
slowing down?
steady cruise?

any vibration?


I dont understand what 1/2 engine revs is...

 

I think it comes from the front/passanger side. And it's definitvely NOT the deep banging of the crankshaft missing oil.
It is metalic chatter with a frequency of some 4-5 per second at 700 rpm (idle). That equals some 240-300 rpm clicking noise - I was assuming that was 1/2 engine rpm, but I might be wrong, it might be even less than that (1/4 ?).
Something like this (I have no good sound, I will try to get one with better sound): YouTube - P1030581

 

New video with sound...
YouTube - Explorer 302 low oil noise

 

did YOU pull the pan and replace the pump or did someone else do it?

I think i'd drop the pan and check the crank and rod bearings....it really doesnt sound right to me.

 

Somebody else replaced the pump. Didn't touch the bearings. It is an AWD - it involves either pulling the engine out or dropping the front end and still lifting the engine a few inches. A PITA.

Crank and rod... I think it sounds deeper in the engine and faster, like if I don't fill the new oil filter before installing it. I am thinking about a new engine but I don't think a 302 should die at 95k miles.

 

not filling the filter before cranking motor will cause a semi dry start which causes increased wear on the bearing, then low oil pressure, and total bearing failure.

the clearance between the bearing surface and journal is where you get your oil pressure from. If the bearings are worn out you get no oil pressure.

a thicker oil will help, but a band aide on a coronary laceration wont hold long...

you could try some sae30, or 15w40 but i have a bad feeling its too far gone...

I hope someone else pops in here with some other / better / good news...

 

I agree on the 30 weight oil or 15W40. I had a car with a worn 351W that I ran for years on 30 weight oil. If you aren't in the land of ice and snow it should be fine.

So where do you live, and what's the winter temperatures like?

 

That video is with 5W30 oil I am in SE Virginia, not bad in winter...
I will go with 10W40 today - if is not raining.

 

You can change oil from one weight to another until you've singlehandedly driven the price of crude up $10 a barrel, but nothing is going to fix that engine with it in the truck. It's a goner. The noise sounds to me like the lifters are collapsing at idle because of the lack of oil pressure. The only two things that can really cause low oil pressure at idle that increases with RPM on a warm engine are bad cam bearings or bad main bearings. They don't have to be worn so badly that they are clunking to make your oil pressure go away. I just pulled a seriously tired 5.0L out of my buddy's Bronco a couple weeks ago. It was doing the exact same thing that yours is except it didn't have any noise at all. It ran like a champ and was whisper quiet but had no oil pressure at idle. We pulled the oil pan to checked the bearings and there was no babbit left on any of the main bearings. They had all worn down to the copper underlay.

 

I think that you are right... Unfortunatelly I don't have a trustworthy mechanic and don't have the means to do take the engine out by myself. I don't know how it got that bad - I have bought it at 86k... and this started just before the first oil change. And now, at 92k it is worse. I have a 1996 Sable V6 with 160k miles and doesn't have any engine issues.
I am contemplating to get a reman engine but I heard horror stories about them (like 30k miles life).
Thanks for the input.

 

I agree with the others. The symptoms indicate that the bearings are worn out. Maybe it has 192K. In any case you are going to need another engine. There is nothing wrong with a good reman. engine if is from a reliable company. If you cannot afford a reman. engine, you might look for a low mileage engine from a good salvage yard.

 

Milage is 098xxx so it is really 98k miles. I had till now 5 Ford cars (4, 6, and this 8 cyl), this is the lowest milage. None of the others had engine problems.

I am in between a Ford reman engine (1700$ on their site, I will know if is avail Monday) or a local reman one for 1200$... both same warranty, 3 years. I have another local reman for 1700$, but warranty 5 years unlimited miles.
My wife wants to trade it in... don't think we can afford the luxury of extra payments