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Old 12-07-2021, 05:48 PM
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mwood65 mwood65 is offline
258 I6
 
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Location: Payson Arizona
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Oil Pressure?

I was wondering what the general consensus is on what oil pressure is in the safe limits?


Got the gauges in my 74' Cherokee (258 engine) and at idle it is 20psi and going down the road at around 2500-3000 rpm it has 40 psi.


I thought that was ok but what do you guys think?



Need for concern?
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Old 12-07-2021, 06:37 PM
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Tripwire Tripwire is offline
hey,does anyone here know how to.......
 
Join Date: Jul 30, 2000
Location: WA State
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mine aint that good.....probably 10 PSI at idle if im lucky and 20-30 on the highway....have a tired engine, IIRC the least you should have is like 10 PSI for every 1K RPM ????
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Old 12-07-2021, 09:25 PM
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backroadin' backroadin' is offline
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These jeep sixes were known for low oil pressure. Having 20 at warm idle is pretty good. They might not have had that when new!!
Many a 258 is still tickin' tho, even with lousy oil pressure.
4.0's weren't a whole lot better either.
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Old 12-07-2021, 10:37 PM
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mwood65 mwood65 is offline
258 I6
 
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Thanks guys,

You said what I was already feeling but wanted to make sure.
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Old 12-08-2021, 05:35 AM
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Brynjminjones Brynjminjones is offline
258 I6
 
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Hey, that's the same (if not better than) I get from the newer 4.0 I6 in my '98 XJ Cherokee!
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1998 Cherokee (XJ) 4.0
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Old 12-08-2021, 08:22 AM
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Old Ironsides Old Ironsides is offline
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Super Low

On Ironsides, it is only 2-10PSI at idle, and 20-25 on highway, depending on how hot it is At some point, I'll do the pump mod. Its been this way for at least 10K miles.
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Old Ironsides: '76 J-10, 401 (1406/2131/DUI/RV Cam), TH400, Part Time, 3" lift, 33s, 346K Miles
Ironsides: '75 J-10, 360 (1406/2131/MSD), TH400 QT, 6" lift, 33s, 110K Miles
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Old 12-08-2021, 10:26 AM
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I'd say 20 at hot idle and 40 on the highway is good, really good. The old rule-of-thumb is a minimum of 10 psi for every 1000 RPM. This puts you well within the safe operation envelope. You should not be winding out a 258 anyway - the stroke is very long which makes torque peak at low RPM, and puts a lot of force on the rod bearings at high speed.
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