Alright, I know these oil pressure threads have been beat to death. I have been chasing down a low oil pressure condition for some time now. Good pressure on startup, 5psi or less at hot idle. Pressure rises with rpm, but not a whole lot. Per my signature, brand new built 6.0. Brand new melling pump with the correct o-ring according to their instructions, also pump was installed correctly according to their video. Running 5w-30 synthetic. Coolant temps are 215@idle on hot days, 195 while driving. All of this is verified on a mechanical gauge along with the OE sender. Barbell/diverter IS installed in back of block. Engine idles quietly.

When this issue first started, I was running a high pressure melling pump. I was paranoid, so I pulled the engine and brought the pump/oil pan assembly back to my builder and we both went through it. The cam bearing are all in their journals. The pump seemed ok, no scoring. Cut open the filter, no brass/copper meaning bearings are good. The remaining 2-3 quarts in the pan had no metallic particles in it, but had a strange black sludge at the bottom(assembly lube? This was the break in oil). While all this was apart, I figured an oil pump is cheaper than a new engine, so I made the switch to the hv/hp oil pump. Builder sent me home as we could not find any issues. I do trust my builder, but I cannot see 5psi as acceptable.

The problem still persists after the new pump, and I am out of ideas. What kicks me the most is the quiet idle. I feel like an engine with this low of oil pressure should be ticking. Should I run a thicker oil, like 10w-40? Could the filter have collapsed? Am I draining my pan(LS1) with the high volume pump? Any thoughts will be much appreciated.

 

before startup with these new pumps did you prime the pump with oil?

 

Did this engine originally have Displacement on Demand, Active Fuel Management?

 

Yes, both times it was primed with a pressure pot. It did not have AFM or DOD as it was a 2004 model year block.

 

Did you install the oil galley plug in the front of the block (reside under the timing cover)

 

I personally did not but I my builder showed me the plug kit he used. It included all of the freeze plugs, galley plugs, etc. I also feel like I would have seen that when I switched the oil pump, but who knows. Sometimes I surprise myself...

Thank you for the responses!

 

Just looked through some pictures I took while putting everything together and the oil plug is visibly installed in the block. So that is not the issue unless somehow it fell out!

 

I have had more Engines brought to my shop (that DIYers built) than I care to mention; with no, or low oil PSI.

The majority of the time, I find an issue with the Oil Pick-Up Tube going into the Pump Assembly...
Wrong O-Ring, Damaged O-Ring, Pipe cocked, Etc...

 

I have the correct o-ring according to melling's instructions provided with their pump. I also have a oil pickup tube brace. Maybe I could try the -overfill and tip the car forward trick- to cover the pickup o-ring in oil.
Mind you when I installed this new pump I remember the o ring/pickup-tube combo fitting quite tightly/snugly into the machined bore of the pump, but not to the point where it would split the oring to my understanding. Does that sound correct?

 

What were the bearing clearances?

 

I do not know, but most of my builders motors are high strung race engines, so I am starting to think he set the clearances looser. I may (unfortunatley) switch to a 15w50 oil and see what that does. I will also cut open my current filter and have a look in there.
I asked a buddy who has had his dirt track engine built by the same guy (350 sbc, runs like 7800 rpm) and he says he runs 20w-50 oil, so putting two and two together I think the bearing clearances are just set too loose. I have exhausted just about every other means of checking and verifying oil pressure, other than a pcv issue, the barbell/rear oil plug is incorrect/not sealing somehow, or there is a crack/hole in one of the block's oil galleries causing an internal leak before oil reaches my gauges. I am pretty much out of options, I will most likely just run that thicker oil and ignore my pressure gauges.
If you guys can think of any new ideas not covered here, my sleep deprivation will thank you! LOL

 

Sounds correct.

It is generally a good idea to install the O-Ring with a small amount of Auto-Trans. Assembly Lube (or Vaseline if you do not have Auto-Trans. Assembly Lube) to keep the O-Ring from getting torn or damaged.

 

Update - my builder got back to me and he discovered that the black side skirt coating on my pistons had washed off in chunks and covered the oil pickup tube blocking flow of oil. The piston company (ive signed a non-disclosure) is making this right and getting me a new motor. Hopefully Ill be able to get back on the road before the snow hits!

 

Well ya don't see that very often.
Are you using an Engine Oil Temperature Gauge?
Are you consuming a high amount of Engine Oil?

If the future, try and Post as many details as possible in order to get good detailed responses.
an example would be:

-Which Cylinder-Block, and any Oil-Passage modifications?
-Using AFM/ DOD?
-Using VVT?
-Made any improvements towards Windage?
-Which Oil-Pump, and any Porting, and any modifications?
-Which Pressure-Relief Spring?
-All Main Bearing, and Connecting-Rod Bearing Clearances?
-All Camshaft Bearing Clearances?
-Oil-Pan, Pick-up, Pick-up installed-height?
-Oil Filter Model, stock location or remote?
-Remote OIl-Cooler, or Component that requires Engine-Oil (such as a Turbocharger)?
-Oil used, and how much?
-Which Port or Ports are being used to measure Oil-Pressure?
-Which instrument is being used to take the measurement?
-Secondary Oil-System modifications (such as Piston Oil-Squirters)?
-ETC.

And the List goes on and on.

 

That's a first I suspect. Good that the builder went the distance to get it resolved. And I know all about losing sleep over stuff like this, hopefully it all comes out right this time. Sounds like a real potent machine!