Low oil pressure?

[Preems14]

At highway speeds and under hard acceleration my oil pressure drops significantly. I want to buy a new gauge so i can see what is actually happening not just see the gauge stay in normal and play around a but. Anyone have suggestions?

 

[FordGuy100]

At highway speeds and under hard acceleration my oil pressure drops significantly. I want to buy a new gauge so i can see what is actually happening not just see the gauge stay in normal and play around a but. Anyone have suggestions?

My suggestion would be buy a new oil pressure gauge. The factory ford gauges are more like idiot lights, they dont read exactly what they are doing. For example the oil pressure gauge your reading starts to move when the truck gets something like 8psi of oil pressure, and then it has some sort of resistance in line so that when your driving down the road, the gauge moves and looks like its actually reading something.

 

[subway]

get a real gage in there before you start doing anything. like mentioned you cant trust the factory set up, could be a bad ground floating that needle. same goes with the temp gage.

 

[HammerDown]

Factory quage blows, caused me chest pains more then once.
I installed a mechanical years ago...18-20 psi hot idle >hwy 42-45
In the winter(at times) I noticed my check engine light will even come on at cold start...and will go off after the OE guage moves 1/16 of an inch

 

[Michael Fowler]

Great timing on this thread.
Here is my low oil pressure problem....
I HAVE installed a mechanical guage. I replaced the original nylon tubing with copper this year, becasue after a few years the nylon gets brittle, and I wanted to avoid that.
Gauge worked well. I even gained a few psi of pressure by simply bleeding the air out of the tubing.
Indicated great oil pressure all the way to the IDI rally. Once there it dropped to about 10-12 psi at speed, and less than 5 psi at idle. This also paralleled the factory gauge. I tried changing the oil, thinking perhaps I had used a non-diesel rated oil. No change. Not a noticeable change in sounds regardless of oil pressure indicated.
Then I bled out the tubing again.--This time I saw air bubbles in the oil stream; steady bubbles, not just a few.
So where can air enter the oil system? After the oil is pressurized, any leaks will show up as oil leaking OUT; not as air leaking in. So I am thinking, I must have a problem with the pickup side of the system.
Can anyone tell me where else I might be getting air into the system?
For the record, the oil is fresh, and not overfilled.
Is there any alternative to pulling the engine? ( I will NOT ever drop the pan in the chasis again, ever, period!)

 

[icanfixall]

The oil pressure is regulated in the rear oil cooler header. That has a spring in a plunger. As time goes on the spring wears out on the sides by dragging on the plunger. This thins out the thickness of the spring and pressure drops. Ford and International do not sell a repair part for this. Plus its staked into the aluminum housing making removal hard but it can be done. The psd oheaders have a snap ring holding there regulators in place. The springs may be the same size. I have both oil coolers here and some day I will compare the springs for referance. Buying a new rear header is the real only way to fix this problem for now.

 

[Michael Fowler]

icanfixall,
When you say the rear header is the only fix, are you speaking to the low oil pressure issue, or my air-in-oil issue?

 

[redneckaggie]

i agree with michael this thread is right on time. my temp gauge was acting retarted not to long ago and then it became fine. now my oil pressure gauge is running low. no difference in how the truck runs at all. I'm looking at getting some gauges for water temp, oil pressure ,and pyro. what ranges do the water and oil gauges have to be and how do you hook them up. pics would be great but any help is appreciated

 

[HammerDown]

... what ranges do the water and oil gauges have to be and how do you hook them up. pics would be great but any help is appreciated

This is how I did it...T'ed off the rear oil pressure unit so I could use both mechanical and OE oil guages. And for the coolant I had to use the sender that cam with the guage and tapped into the plug infront of the oil fill tube/water pump.
PS...in the below pic I held RPM's at 1800 to show (hot) oil pressure > 45 lbs

You must be registered for see images attach

 

[Preems14]

thanks alot ill try that....

 

[redneckaggie]

thanks hammerdown but where is the oil press send unit at

 

[Michael Fowler]

Factory oil pressure sender is a "can" looking device with a wire sticking out the top, located at the top, rear, center of the engine behind the rear of the intake manifold.

 

[Preems14]

I will check it out tomorow in the light. I can get a water temp gauge, volts, and oil pressure for 30 dollars so if anyone could help me out on where the sending units are for this that would help me out alot.

 

[Devilish]

Oil pressure dropping under load but rising back up when you let off on the gas means that your main bearing clearances are excessive. Before you blow that engine you need to do rods and mains cause it's alot of work so just do the rods. I also recommend red locktite on rod bolts but clean the nuts and rod bolts real good with brake cleaner.
To explain further, when under load the crankshaft is pushed against the main caps more causing more clearance between the upper main bearings which means less resistance for the oil squeezing by. This also causes less oil getting to your top end.

 

[HammerDown]

Oil pressure dropping under load but rising back up when you let off on the gas means that your main bearing clearances are excessive. Before you blow that engine you need to do rods and mains cause it's alot of work so just do the rods. I also recommend red locktite on rod bolts but clean the nuts and rod bolts real good with brake cleaner.
To explain further, when under load the crankshaft is pushed against the main caps more causing more clearance between the upper main bearings which means less resistance for the oil squeezing by. This also causes less oil getting to your top end.

Could be but lets not hope so...
Before the original poster gets all worried...and thinking he as to yank his engine out I still suggest he install a quality mechanical oil gauge first.
*The SAME EXACT thing Delivish described above happened to my Corvette...turned out to be a faulty electrical sending unit for the OE gauge.