yeah so it seems something would have to be blocking it up.

could a clogged sump tube cause those symptoms??
im trying to figure out what else could cause low oil pressure even after a new oil pump is installed.

 

On the 4.7L, 5.9l,5.2L, and 3.9L engines you have to remove the screen and oil pickup tube when you remove the oil pump. Seeing that you should have seen the screen and pickup tube and cleaned as necessary I would rule it out.

One thing I would not rule out is the rod and main bearings on the crnak. If the engine was worn out (meaning the bearings) then it gives you a higher reading on cold and low reading on the warm/hot side. One way to ensure this analogy is to install a heavier weight oil and see if you have more pressure or even less fluctuation. Maybe try a 10W-40 oil and see if there is a large difference, of course you shouldn't run it, but it's good for a simple test.

If the test comes up presumptive positive for worn bearings I would then drop the oil pan and remove one or 2 of the rod bearings and see if there is a copper coating on them, which if there is shows you that the bearings are worn out. If there isn't copper then I would measure the clearance on the ones that you pulled using a plasi-gauge and see if you are in specifications again showing whether you have abnormal ware on the motor.

If you do have any bearings with copper showing on the journal face then you should replace all of the rod bearings and main bearings as per the manual to bring it back within specifications. Usually you would need larger bearings over stock to suck up the ware on the crank journals.

You see, oil pressure is determined by the clearance between the bearings and the crank. This is why a mechanical gauge rules out electrical sensor miss-interpretations. Once you are sure the oil pressure is actually low using a mechanical gauge, oil pump replaced, pick up tubes installed correctly, correct oil weight and level, and new oil filter, then it must be the bearings.

 

would the sump tube from an 01 be different than a 00??
I switch sump tubes when i replaced the engine.

however this time when replacing the oil pump i didnt completely remove the sump or the oil pan. Just moved them aside enough to pull the pump.

I imagine worn bearings would have more symptoms right? what else should i be looking for if i have worn bearings??

 

Just another reason I'm glad I went the over-haul kit rebuild on my blown 4.7 instead of just replacing the one blown up piston. All my rod bearings were showing about pure copper...

 

correct me if im wrong..but is there an incorrect way to install the sump tube??

also if i put 20w 50 in for the test would i be going over board?

 

I don't know if there is an "incorrect way" on that motor for sure. I would assume that you actually pulled the whole thing out and replaced it, not just installed a new inner and outer rotors (basic rebuild).

Yes that is overkill. Besides 20W-50 does not have the additives needed in your motor and the oil ports are to small to drain back into the pan correctly giving you false readings. 10W-40 will have all the main necessary additives needed for the test and should not hurt your motor, for a very short time mind you.

I gave you the information you need, re-read my last post and it answers your questions. Follow the instructions.

 

thanks for your time and help

 

well finally got the 10w 40 in.
the test was done separate days at about 90 degrees ambient temp each day. Only letting the truck idle up to operating temp.

From a cold start with the 10w 30 it took about 18 min for the dashboard pressure gauge to drop off to red. with the independent pressure gauge reading a litte below 8psi.

The following day the 10w 40 took about 32 min to drop to the red, with the pressure reading slightly below 10 psi.

Does this seem to be a bearing issue???...

EDIT: just for the heck of it we put in 20w 50 and had the same results as above.

 

bump up

 

Finally getting back to this thing. With everything else ruled out now, the bearings are my only other choice. Does anyone know what size Plasi-guages i should be looking for??