Hey let me first start off as, this is A 1999 Ford F350 7.3Liter Diesel Truck.

275,000Miles I am the second Owner, The original Owner bought this truck Brand new. I have all of his service Records.
He kept this truck clean and serviced it every 3,000miles.

I know he hauled and used this truck as it was meant to be used. things done on the truck have been.- 1inch Blocks. 35inch All terrain Tires. Banks Power Stinger Plus System. Custom Automatic Transmission with Suncoast Converter, TransGo Tugger Kit, Alto Clutch Packs, Mag-Hytech Pan. 456 gear Ratio.

The High Pressure Oil Pump was replaced at 175,000miles
all Ford Recalled items have been replaced.
other then that nothing else has been done.

Owned it for a while then the Problem started.

Fact 1. At idle the Dash gauge would sometimes flicker and the lite would come on. this would (return to normal) when the RPM was at or higher then 1,000RPM.

Fact 2. my Dad and I put a mechanical gauge on it. Oil Pressure at idle read Zero. at 2,000RPM it still read Zero.

Fact 3. We Diagnosed that, it could be the Oil pressure regulator valve. or the Engine Oil Pump.

Fact 4. Replaced the regulator valve unit. and Replaced the Engine Oil Pump with a Melling engine oil pump.

Fact 5. Put the Mechanical gauge back on. At cold idle read 50psi then slowly came down to 25psi at 2,000RPM read 50psi and held.

Fact 6. (took her up the hill. came back) At Hot idle read Zero. at 2,000RPM read just 25psi.

where's the Oil Going?!? although Replacing the Oil Pump and regulator valve unit made a big difference it's still not where it should be. The Engine is not Knocking it sounds great. so my Dad and I don't think its the main Bearings.

what else could it be? anywhere else the oil could be squeezing by? what I'm I missing here?

 

Once I ran into these 7.3 l eng spitting out the oil galley plug on the back of the eng,

It will not leak out, underneath the rear main seal housing,

Might be where your oil is going,

 

Alright thanks. I'll be checking that and the pickup tube, and few other things. hopefully one of them will be the problem.

 

Alright so, I checked the pickup tube just in case and it seems to be working properly. I haven't pulled the Valve covers yet but will probably be doing so soon. Turns out My dad has a scanner, we are looking for it when we find it we'll scan and see what turns up.

I put a mechanical gauge on where the filter housing unit is.
Here's the difference between checking it there and the reservoir.
Reservoir, Hot idle = 0psi. 2,000rpm = 25psi.
Filter housing unit, Hot idle = 0psi. 2,000rpm = 45psi.

I'm confused?
I've been told it could be the rocker arms or maybe the oil galley plugs?
any thoughts?

 

preety sure the scanner will not tell you much, sounds like you have a mechanical problem,

Poking around with your manual gauge and checking things like your doing is the best bet,

Oil galley plug under Rear main seal housing is where my money is, pull the tranny and check ?

 

yeah your probably right. but we figured mine as well since we are into everything else.

alright I'm getting to that point. a few questions before I dig in there. if it is the oil galley plug would I be dripping oil externally? I don't really believe so but thought id better ask just in case.

 

would I be dripping oil externally?

No

The plugs are under the Rear main seal housing that bolts on the back of the eng,

The oil just cycles right back down in to the pan, no leak externally,

Now I only ran into this once, so not a common problem, Now I will say that on this Job I actually had to do it twice, I pounded a plug back in but in the test drive phase the darn thing spat back out,

So if it is the oil galley plug make darn sure it stays put,,,

In hind site wondering why this happens to begin with , could it be higher oil pressure is back feeding from the secondary oil pump?

Is there a one way check valve or something ? Just wondering,

 

I pulled the left valve cover, everything looks brand new (believe it or not)
I'm pulling the right side later today if everything looks as good as the left I will go down under and check the oil galley plugs. I don't trust myself with pulling the transmission I'm looking for a shop to do it for me just a question though if it is the oil galley plugs would it run the symptoms I'm having? good pressure cold bad pressure hot?

 

Discovered the problem, A Piston oiler Broke off/Fell down into the bottom of the Oil pan.