Sorry this is so long.......
FYI. I thought my rebuilt engine was toast.
Mech gauge in the top of the res. 11psi at idle. 22 at wot.
Moved the gauge to the test port in the filter housing. 60lbs at cold idle and with a short run over 1400rpm can crack 75psi.
Hot idle is 16psi and wot is 55+
Been 3 years now.
Very odd on a common shared oil system to see that much variance.
Literally no matter how hard I tried and what I changed. The pressure Would not exceed 22psi in the res at any rpm.
Not sayin that's your issue. But check at the mains.
I have seen this a number of times and once on my setup when I was running dual HPOPs without adding an extra feed line to the HPOP Res. That in combo with faster injectors using more oil mine were not huge but still 200% 460cc More oil was ending up going down thru the HPOP system and into the pan.
Here is what I see is happening:
While in a stock system its a good universal place if you have to have only one for the oil pressure switch if you really want to know the pressure that is going thru the passages in the block its likley the worse place. To me the HPOP res is the low pressure side of the engines oil system (LPOP). Its nothing but a holding tank to supply oil to the HPOP/injector system.
Now look at the system itself:
It has one pipe feeding the HPOP Res and it was sized for a stock demands. Yes good amount for growth compared to what its was used for stock but still it was setup to handle a standard HPOPs volume as well injectors. Run a dual hpop (as you are Ryan with your dual termy) and even more so if you run a remote IPR and have it exiting to the pan and not back into the res. Also any extra oil in the res just dumps down the front cover so its not as if its under a very restricted return orifice.
When I installed dual stealth HPOPs you could watch the stock gauge bounce all over the place and the oil pressure light would trip. Put a mechanical gauge and ran it into the cab and you could see the same thing. It would bounce off the zero pin stop and back up to the normal range. When ever you had a high HPOP demand especially at lower rpms you could easily see this dramatic dance. You could watch the pressure move all around based on the HPOP demand and RPM.
Yet at the block locations pressure was always much higher pressures and no where as erratic. There would be some variation but pressure was always decent.
Added a Melling LPOP (BTW the Melling is not direction dependent on install like the OEM pump. The gear can go in either way. There is no arrow or direction, its the same.)
The addition of the Melling helped across the board but in the same ratio of oil pressure variation. So all the pressures were higher but still the large variation.
Added a extra -6an oil feed line from the block up to the HPOP Res ( this is where that extra HPOP spacer such as Bob Riley and Riff Raff sell helps out with the extra ports in it) I drilled mine into the stock res. Now you have another source feeding the HPOP Res and a more powerful pump to help keep up with over all demand. Now pressure stayed above the 10 psi no matter the peak demand and no more oil pressure light and engine block pressure stayed at the top end as well. All was good.
When the engine gets hot its not as if there is for sure less flow it can be just less resistance as the viscosity is now much lower and as its a fixed rot pump its moving the same amount of oil for a given RPM. The exception to this is when you have a issue such as oil passing by the LPOP becasue of wear in the front cover or some other wear at the pump etc. The thicker oil does not flow past but as it thins it can and does so and this is actually effecting flow rate.
The Riff Raff or Diesel Site HPOP Res spacer neither helps or hurts the actual oil pressure. What it does is to increase total HPOP Res capacity and as an aside it also increases total engine oil capacity by the same amount. This is helpful when running large HPOP and oil hungry injectors in that it gives more capacity before it's empty which then causes injector running issues.
The second the oil capacity in the HPOP res drops enough to effect the pressure you are going to see that on the gauge. There could still be oil right up to the top of HPOP Res drain even over it pouring down the front cover but its no longer under positive pressure in the HPOP Res compartment. This has no effect on the injectors or HPOP system as its the HPOP that is what makes pressure there. But it sure looks to scare the crap out of you as that is where Ford/IH decided was best for the engine oil pressure switch. Frankly if you have to run only one it sort of makes sense to cover all the systems yet 2 would be better.
The other benefit as I mentioned to that spacer is it has IIRC -6an ports. That is perfect for running extra oil feed lines to the res from the block.
So, as long as there is any pressure at all during the peak demand then it going to have no neg effect on the HPOP/injector system. If there is any pressure then you know the Res is at the very least full and as it feeds the HPOP from the bottom of the Res that means you are GTG.
Even though its not a negative to the HPOP injector side of things it can still have an effect on over all engine oil pressure. As the HPOP res pressure increases that allows for that resistance to increase pressure in the rest of the block oil passages in ratio to it. So while it does not effect the injector pressure, those increased demands still can have an over all effect.
The answer there has always been to swap to the Melling which you have. Not to mention others are running similar setups and not having the large variations you show especially at the block at idle.
To answer your question in regards to the oil pressure regulator in the oil filter block being able to drop idle pressure but you still get higher RPM pressure: The regulator could be allowing some oil flow to pass by it at all pressures including low (basically its not closing the full amount it should) but the the LPOP spins up with RPMS its able to overcome this and reach its max pressure as its a small bypass bleed. So its enough to effect the low rpm pressure where the pump is moving far less oil. If you were to shim that regulator you can increase the block oil pressure even higher that 60-70 psi at higher RPMS. Without the regulator oil pressure would keep increases in ratio to rpms so 65@ 2K rpm would be what at 3.5 or 4K rpm?
I am not saying that is the answer or what is wrong just that this is how it "could" cause the issue you are seeing.
I think in this case looking at the HPOP vs engine block oil system the symptoms points to it being on the engine oil system side or LPOP side.
I am quoting some of the info you have put up in a few of your posts so we can have it all in one place. It will be the oil pressures at the block (oil filter) and at the HPOP Res so we can see the relationship.
"Plumbed in the mechanical gauge on the top of the HPOP reservoir, there was like 2-5 PSI when the oil was hot. Rev it up to 2000 RPM and it had like 45 PSI."
"
plumbed the gauge in by the oil filter housing. Engine was
cold then. Fired it up Idle pressure was like 25-30 PSI cold and then
as it warmed up, it kept falling to down around 5 PSI at an idle when warm.
When the truck was fully warm, I revved it to 2000 RPM and the hot oil pressure was about 55-60 PSI at the filter. I put the ford sending unit back in and the gauge would drop to nothing when the engine was fully warm. Rev it slightly and the light would go off and the gauge would register."
Oil Pressures:
HPOP Res:
**Hot: Idle:
2-5 psi 2000 rpm:
45 psi
Engine Block (oil filter block):
** Cold: Idle: 25-30 psi
** Hot: Idle:
5 psi 2000 rpm:
55-60 psi
So if this was a issue say with the HPOP system pulling oil somehow etc you would see a large variation between it and the engine block pressure. Example of this would be DieselBoy. But that is not what we are seeing. Here you have hot idle psi being almost exactly the same at both the Res and the block(oil filter mount port location)
Rev it up under no demand using very little oil in the system as most of it is passed thru the IPR and back into the res. So the rev ups not under load being so close is not surprising.
But the hot idle being the same and the fact there is this huge drop off from cold to me looks as if there is a leak/bleed somewhere in the LP system.
My first thought keeps coming back to that oil bypassing the LPOP and specifically the front cover mating surface. Its from your comments about it Ryan.
You said the builder said the LPOP was shot, but it was relatively new Melling, so if it was bad it had to be from the engine letting go. But at the same time you said the same front cover was reused but that you did not inspect it prior to its reuse for this build. Further you are noticing oil drip from the LPOP mounting bolt location. All of that with the what you are seeing with oil pressure would have me checking into that first.
While less likley especially as you have already check it the pressure reg in the oil filter mount.
One thing to take away from this that is sort of positive is whatever is the issue with the oil pressure bleed its relatively small in terms of volume of oil. Otherwise you would not see pressure shoot up the second any RPMS over idle are spun up. Its not that it only gains proportionally but it actually jumps up to the top end limits of the oil pressure regulator. Thus unless its something mechanical like a oil cooler jet etc it sounds like the engine is getting lubrication. Thus chance of damage might be minimal. Still I would want to figure out the issue.
Ryan,
When you replaced the oil cooler's o-rings I assume you made sure all the passages thru the cooler were clean and unobstructed? I figure as much by what you wrote just wanted to be sure.
Pull the LPOP. Clean up the its mounting surface on the front cover and take some detailed photos of it as well as the the mating surface of the pump. Also check the seals etc as you should not have oil coming from the pump front cover joint. H-Balancer if they tried to bang it on etc I have seen oil leaks more often.
