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Acceptable oil pressure?

Texan01

Well-Known Member
Joined
November 16, 2001
Messages
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City, State
Dallas, TX
Year, Model & Trim Level
1995 Explorer XLT
What's the acceptable oil pressure for the OHV 4.0?

Mine with 250k miles on it hits about 55psi @ 2,000 rpm hot and between 15-20psi at idle hot. Cold it hovers around 60psi until it warms up. According to the book and everything else I've read it's dead-on spec, but I'm just curious.

It rattles a bit on start-up but I've found a worn-out rocker arm causing that. No mysterious noises otherwise.

Otherwise it runs cool and quiet.
 



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Here is what we have on our newly rebuilt 4.0 ohv (it has 25k miles now).

Hot idle is 20ish..
Cold idle is 50ish
2k rpms when warm

Our old motor with 300k+ miles was just < 20psi at hot idle, and cold idle and 2k rpms when warm was about 40..

btw.. by hot, I mean 30 minute drive on the freeway in 100F weather.

~Mark
 






Cool, so it's still reasonably tight after all those miles.

Mine gets down to 15psi when it's been sitting in stop-n-go Dallas traffic on a hot day with the A/C cranked. Otherwise it's around 20 when it's been run on the highway like yours has.

So I guess I need a new sending unit, again. I may just convert it back to the idiot-gauge just to squash replacing the silly thing every 10 months, or order a Ford one instead of the Borg-Warner fail-o-matics.
 






My 99 Sport has 154k on it ...

And its oil pressure is 20-25 psi @hot idle, 50-60psi rest of the rpm range hot,
60-75 cold startup using 10w30 Mobil 1

I have used 5w-20 Mobil1 in the past and had the same results... I did replace the oil pump when I bought the truck due to extreme sludge buildup in the pan and top end...

Engine temps do not have a significant effect on mine oil pressures... When the engine warms up to or past 150F, the pressure stabilizes...

And I am in Austin and Houston/galveston all the time...
 






Keep in mind that oil pressure is not an indication of anything more than the resistance to flow. You can have 50 psi at idle, but could be starving the engine for oil. By the same token, you could have 5psi at cold idle and everything could be fine inside the engine (albeit, just a little worn out)

That's part of the reason they use a dummy gauge. Most people see an oil pressure fluxuation, and panic.

-Joe
 






I had remembered the old rule of thumb that 10psi per 1,000 rpm.

Just curious for the most part. This is the highest mileage car any of my family has ever owned, so I'm just trying to stay on top of things.
 






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