Oil Pressure
Thread Starter
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Senior User
Joined: Jan 2007
Posts: 298
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From: Mexico
Oil Pressure
I have a 1990 F250, 7.3 IDI. What should my oil pressure be when running at operating temps. I am running about 25psi at idle and 45psi in 5th gear at 2200rpm. Is this on the low side?
Thanks
Thanks
Thread Starter
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Senior User
Joined: Jan 2007
Posts: 298
Likes: 1
From: Mexico
Originally Posted by PLC7.3
That is perfect......we do flow more than pressure.
Normal required oil pressure is:
10 PSI hot idle
40-70 PSI at 3000+ rpm
Normal required oil pressure is:
10 PSI hot idle
40-70 PSI at 3000+ rpm
Why the big difference in pressure readings at 3000 rpm? Wouldn't the higher the pressure the better protection?
Thanks
Elder User
Joined: Dec 2006
Posts: 559
Likes: 4
From: On a farm.
Remember that pressure is only an indicator of resistance to flow. You can flow 25 GPM at 10 PSi, or 25 GPM at 25 PSI. You need some pressure to achieve flow, but once the engine has reached its required flow, more pressure is useless. It can even be detrimental. If your oil pump has to carry a big head of unneeded pressure, it takes more power, can cause leaks and even blow oil filters. Nope, your pressures are right there where Navistar designed them to be. At idle, they are a little higher than normal. Be happy!
Senior User
Joined: Nov 2007
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3000 Rpm?
Some of the newer IDIs must be alot different!
My 87' would run forever at about 2000RPM with
neglible oil pressure indicated (about 60MPH with
a C6 and the tire / rearend combination I have).
At about 2400 RPM its' telling me no more plz!!
My 87' would run forever at about 2000RPM with
neglible oil pressure indicated (about 60MPH with
a C6 and the tire / rearend combination I have).
At about 2400 RPM its' telling me no more plz!!
Elder User
Joined: Dec 2006
Posts: 559
Likes: 4
From: On a farm.
If you have a C6 and 4.10 gears, 3000 rpms is very common. I did a 7K miles solo cross country trip in the truck back in '99 and did it all at around 3000 revs (70 mph). Fuel economy sucked.
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Senior User
Joined: Nov 2007
Posts: 175
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I recently changed the rearend to 3.31 and
have 33 inch diameter rear tires. With the
previous 3.54 and 31.5 inch tires, 2000RPM
produced 53MPH. I got 20 MPG with that
original config (E350) pulling a 1200# trailer
or not on the flat. I'm expecting about 25 MPG
at 55 MPH with the new setup but I havn't put
enough miles on to verify!
have 33 inch diameter rear tires. With the
previous 3.54 and 31.5 inch tires, 2000RPM
produced 53MPH. I got 20 MPG with that
original config (E350) pulling a 1200# trailer
or not on the flat. I'm expecting about 25 MPG
at 55 MPH with the new setup but I havn't put
enough miles on to verify!
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