Never did cut open the filter on the Durango, but over the weekend I did cut open the filter on my Dart as the oil light started to flicker at idle whick it hadn't done before. Found all kinds of curd in there. Previous owner resurrected it after sitting for years before I bought it and I suspect dried out sludge working loose, and the above mentioned valve stem seals might be it's problem.

I once bought a 5th avenue for $300 that had the oil idiot light blinking on and off. Took the oil pan off and the pick up screen was full of the broken off nylon teeth from the timing gear and other gunk. Cleaned it all out and problem was solved.

My car was working fine, BB engine just a few years old and always run fine and maintained. I changed oil & filter with a Napa 51515 filter, pressure normal for about 30 miles then zero pressure on mechanical gauge. I check the drive gear and it was fine, removed valve in pump on BB and it was fine, no grit in there. Still zero pressure. I tried a new filter and pressure came right up, nd has been fine for years now. Bad filter somehow. Try that first and see.

1. Well, the tapping upon gauge loss of oil pressure indicates that it really is low oil pressure.

2. Most oil filters have a bypass that lets oil around the filter when the filter can't pass enough. So unless you specially bought a filter with no bypass, it isn't the filter.

3. I've never heard of gunk INSIDE an oil pickup tube

4. The scenario of stuff clogging the pickup SCREEN is plausible.

5. ALL commonly sold motor oil has detergent in it. So the idea of a "detergent" oil cleaning up an engine that had only been run on "non-detergent" motor oil is just plain wrong, unless one is starting an engine that hasn't been run for more than a half century.

6. Diesel lubricating oils have high levels of detergent because the oil carries a truckload of soot

7. My initial diagnosis was sticking bypass valve in the oil pump. That would explain the on/off nature of your problem.

8. DO change the filter first, it is inexpensive and easy to do. Then drive the truck and see if it happens again.

9. If that doesn't work, you have to drop the pan. While you're in there, change the pump. I have wasted two engines because I didn't change the pump. The original oil pump looked fine, but once engine warmed up, oil pressure went to around 5 psi.

10: To check the condition of rod and main bearings, look at the #1 main and the #1 rod journal. As these two bearings get their oil last, they are the first to go. My second 318 crank is reusable except the underside of the #1 throw is terribly ground down. The #2 rod bearing was perfect. On the same rod journal I had both no wear and extreme wear.

11. One of the culprits I see here at work all the time is shuttle valves sticking because of varnish buildup.

R.

R.

Pull the pan. By the time you go through all the "easy" stuff you won't have any engine left. The fact that the cam went south for the PO and he didn't pull the pan is a red flag.

+1, The previous owner already told you the engine ate a cam, so, all that metal clogged his filter, it bypassed due to the clog sending unfiltered dirty oil through your engine. Your oil pump took the first hit, it probably looks like it's been sand blasted internally. The metal filings have your oil pump pressure valve sticking causing your pressure variations. Before running the engine any more drop the pan, replace the pump, check your main and rod bearings to see how much damage they took. You may get lucky and find the bearings aren't too bad but I'd say they received some damage too.

Might help if you bleed the air out of that clear tube going into gauge. If there's air in the line the gauge doesn't read properly. Just fire up the motor, crack open the line at the gauge and when you have oil escaping without air bubbles tighten the line. Let's see what the gauge reads after that.

Yup. Experienced exactly this on two different LA engines. Identical symptoms to the OP...

Sob the oil pan is clean. Guess it'll be nice to have a new pan gasket lol.

I'm gonna disconnect the tube and see if anything is inside

I would say that I should've just taken off the filter 1st, but I know myself and even if the filter is the clog point, it would've constantly bugged me that I didn't know if the pan was clear or not.

Next step, off with the filter

My filter

I believe that it filters from the outside to the inside. What does it look like between the pleats? Given how white it looks doesn't look like the filter was in there that long.

Yeah and I just disassembled and cleaned the oil pump and pick up and there was no gunk in the pickup tube at all... I blew out every passage I could with compressed air and nothing sounded blocked up. So besides the possibility of the oil pump itself failing which I don't think it's likely because how randomly it fails, I'm stumped on the problem

Really hoping I don't have little tiny pieces of camshaft crammed in the tiny oil passageways in the block

Did you pull the bypass out of the pump?

It takes only a very very small piece of debris to make it stick.

Believe the gauge........ It coincides with the lifters clattering.

If you already have the pan off, just replace the pump. It's cheap insurance.

Okay, now before you do anything rash think about what you have found. If the pump is good (including the relief valve), the pickup screen and tube are clean with no cracks, and the oil pump drive gear isn't slipping on the shaft, the oil pump HAS to work. It has no choice. There is still something there.

Possibly, the oil pump drive shaft is slipping inside the drive gear?

When you're ready to re-install a new oil filter, don't cheap out. Go with a quality filter. I'll recommend K&N,Mobil 1 or Wix.Your oil pressure gauge seems to be working perfectly.

I repeat: replace the pump, even if it looks OK. You can get a brand new Melling or Enginequest pump from Rockauto for less than $40 delivered. I took a chance on an Enginequest pump when they were on clearance, it is the same casting as the Melling and is made in USA. High volume will run closer to $70.

It still sounds to me like the oil pump pressure relief valve is sticking open occasionally. This allows for the pump to be working which we know it is, as some times the pressure is where it's supposed to be. Then the engine speeds up to where the bypass opens and the little piston sticks. Now as you slow down the pump pumps less and the bypass is still open. Most of the oil from the pump goes right back into the sump.

On to checking bearings, I'll also repeat you should pull the #1 main and the #1 rod cap and look at the bearings and journals. If they are OK, the engine didn't suffer any permanent damage.

R.

Sorry for late reply. Shaft looks good.

Pump being replaced along with Oil with a little zinc, and decent filter.

When I smelled the oil it smelled like gas. Then I realized the pump is on or off only, so when the key is on, the pump is on. Could had been flooded many times by the po, and myself. The gas in the oil could explain the surprising cleanliness of the crankcase and head. Maybe a lack of lubrication messed up the pump and also caused the ticking?