2001 no oil pressure when warm.

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Tiha

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I have read stuff all over the internet and out of things to try.

Put used engine in. Around 130 k miles. Was in running driving explorer but did not drive far or check oil pressure. The cats were gone so if knocking I would not have noticed.
Before installing verified cassettes are good.

Start engine, all is well, oil pressure is 40-50 psi.
After 5 minutes it is 3 psi at idle.
Maybe it would go lower but I shut it off before that

This is tested with manual gauge.

Pulled pan. Replaced rods and mains. They weren't horrible but bad. Also installed new high output oil pump.

Started truck. Again sounded great. After a few minutes thought I heard knocking. Assumed I spun a bearing.
Was showing 0psi at idle.

Pulled pan, checked rods and mains, all good, looked like new.

Pulled new oil pump apart it is trashed, all scarred up. Assumed faulty pump.
Got another new pump, with new pickup tube.
Reassemble.

No change. Oil pressure loss. 0-3 psi when warm. Sounds like a knock. Just like before.

Oil filter was also changed when 2 nd pump was put in.

Pulled intake, pulled oil pump drive. Looks good, solid, no slippage.

I have no idea what to check next.

Runs great, no chain rattle but my oil pressure is going somewhere.

Help?
Thanks
 

DILLARD000

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Welcome to the Herd! Lots of friendly knowledgable folk in these forums.
This is a mysterious one. For my & others info:
~ what Make+Model HiOutputOilPump & OilFilter did you install?
~ where are you connecting the Gauge & measuring OilPressure?
Sounds like something is warming up, swelling up, & blocking oil flow+pressure?
 
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Tiha

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Melling 328 ho oil pump.
Now melling 128.
Keep in mind it also did this with the oem pump.
Oil filter was O'Reilly's cheap one
This one is a carquest brand. Still cheap.
I removed the oil pressure sender and put a T in there, adding the mechanical gauge.

I am thinking it is cam clearances, meaning heads are shot or maybe balance shaft.

Would a hydraulic tensioner do that?
When it gets hot. Start knocking? But I don't think they take enough oil to drop pressure to nothing.

I find people all over the internet complaining of same thing but nobody fixes it. Or comes back and responds.

I am on the fence, selling as is or fixing. I can't work on this thing forever.

Thank you.
 

DILLARD000

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On these V6~4.0L~SOHC engines,
OilPressureSender signal is typically slow to pop up & improves with warmup; so that connection seems OK.
Is the Factory\OEM flow restrictor in the Oil PassageWay next to the LeftFront TimingTensioner?
Here I'm considering deleting the BalancerChain, next time the CoolantPump+FrontTimingCover is off.
 

Tiha

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I can check for the restrictor.
This donor vehicle was a running driving 2003 or 2004 explorer that the transmission went out of.

We pulled the valve covers checked it for sludge checks the timing chains and cassettes it looked great they weren't brand new but they look like they'd been replaced and it had been run like that for a while.

What about the lifters could they do something like that?

As I sit here and ponder it I wonder if the knocking noise which isn't really knocking it's more of a thumping
I wonder if that noise is the cause of the low oil pressure or a result of the low oil pressure

When the engines cold it runs and idles perfectly smooth when the oil pressure starts dropping it develops this thumping noise and maybe it's missing kind of hard to tell because your attention is split

And I was just thinking that when I was running it last night I might have heard it spit back through the intake once and backfire which of course would point to a valve train issue

I am trying to talk myself into putting the intake back on pulling the valve covers and running it for a while
 

Tiha

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Is the oil pressure regulator in the pump?

Anyone have pickup tube problems?

I am still stuck on bad oil pump. Again. Or faulty pickup tube

Had bad cloyes timing components fail in 5k miles. Bad ones out of the box.
Why should melling be any different?

Had an electric fuel pump from summit once, it actually took running it in a bucket to find the problem.
 

Tiha

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Anyone ever ran into this?

So I found the pressure relief is inside the pump. Under the pickup tube. never paid attention before.

The HO pump did have this slug pushed out slightly and it had a plastic pickup tube. I did look close enough to see there was no visible gap. Wouldn't take much of a gap though. I am sure when it warmed up that plastic became more flexible.

This last pump has a new pickup tube, but It was plastic and I see on the oreilly's website it is shown as steel.

maybe my new rods and mains are creating too much pressure? More than the pickup tube can handle. Opening a gap and allowing air?

These melling pumps come with gaskets. the OE pumps where all machine fit. Is that to fix a design flaw? Or to cover up manufacturing defects on their part?

Not sure if it will tell me anything but I think my next attempt is to make an oil pump driveshaft and run it off a drill for like 15 minutes and see if my oil pressure drops. If it does it has to pretty much be pump related.
If it does not, not sure what direction I will go.

I hope to watch oil on the dipstick too, maybe it is all getting pumped into the valve covers and not returning fast enough.

 

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Tiha

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I could not build a priming device, well I could but I didn't want to destroy a socket. As I sat there thinking about it, either way I would end up pulling the pan again.

So I got to thinking about it while dropping the pan, I only checked one rod and one main with plastigauge. That was all I had left and I actually only did that because the engine was a used unknown. The last 3 or4 I have done I never even checked it. With torque to yield bolts I get nervous and really in my whole life maybe twice plastigauge told me something I didn't already know.
Don't get me wrong, on rebuilds, or new crank/rod jobs I always check them all. I am not saying you shouldn't do it.

I actually had better oil pressure and no thumping sound before replacing rods and mains. I had even driven it to parts store once. I would never drive it the way it is now.

Got the pan off, the oil pump bypass looks perfect, not pushed out. The pickup tube looks perfect, not deformed, no cracks. I may still run it in the bucket.

My next step is to plastigauge the rest of the rods and mains. I went through all of the old ones I pulled out and they are all standard OEM Ford. I visibly checked every one I installed and they were all marked standard. But who knows, maybe sealed power let me down this time.

Ran to advance, they were out of plastigauge last night, Went to oreilly's they were closed due to short staffed. Went to autozone, they said they were out, but other store had 5, went to other store the guys couldn't find it. Stopped by other orielly's they closed early.
Yep this is how my projects normally go.

So I have one goal today, find plastigauge in town.
 

Tiha

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Well mains 1&2 did not even touch the plastigauge.

3&4 come in between .001-.0015

Rods all came in between .0015-.002.

I swear the weirdest crap happens to me.
The main bearings are all marked standard. Crank journals are the same best I can measure.
Old mains all have same part number.

Just had to be boxed wrong.

I will order more mains. I hope this is the end.
 

Tiha

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New mains, everything plastigauge perfect.

No oil pressure when hot. Has knock.
Sounds deep like jackshaft or maybe balancer.

Used engine must have been junk. Even though it ran great could not hear anything because cats were missing.

Anyway I'm done. Gonna sell or maybe scrap because tired of dealing with liars and cheats
 
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