4.0L ,318 or 360 V8?
I would say you have good oil pressure if the needle is in the center or just above. the pressure needle should not be all the way to the left or right.
cold, idling, most V-8s should be around 30 lbs. Hot, idling, about 20. Usually maximum on a V-8 is about 60 lbs, unless you have a high pressure or high performance oil pump installed. Then you can get 80 lbs of pressure maximum... Most V-6 and 4's average about 5 lbs less across the scale...
I had my oil changed at the dealership yesterday and this morningthere was two spots. I have a 2013 Jeep Grand Cherokee and the oil pressure is reading at 38 to 45. temp 171 to 181
If you have a 4.0 jeep engine and having oil pressure problems here what your issue is! The 4.0 cylinder head is extremely bad about cracking across the top of the head near the rocker arm towers. It allows coolant to seep over time and sludge the oil causing low oil pressure at idle around zero and higher pressure while driving. I just pulled my engine to rebuild it and the oil looked like sea weed. The machine shop I use all the time said the 4.0 heads crack all the time. I found a company the remanufactured new heads that are stronger and thicker where they crack all the time. Go to my website send me an email and I'll give you there info. bigasautorepair.com just click on contact us. Hope this helps!
My grand Cherokee 4.0 has 258,000 miles and the oil pressure is 40 at idle hot or cold and 45 at speed hot or cold. Change the oil no difference I am using Rotella 10W-40
Allynnc, 40 psi at idle and 45 psi while driving is a good oil pressure for the 4.0 liter Jeep Engine. My problem was my oil pressure was dropping to 0 psi at idle and the problem was coolant was seeping from the head because it was cracked, so I rebuilt the engine and it is fine now. 60 psi at idle cold and 40 psi at idle warm. I had know Idea it was a coolant and oil sludge problem until I sent the head to the machinist and he said the 4.0 heads crack because of a thin layer of cast across the top of the head. I found Titon Engines who had recast the heads and built the up in that weak area. My jeep is running and the oil pressure is better then is was before I pulled the engine and rebuilt it. Thanks
You have to have pressure to have flow. At higher RPMs your pump is working harder and your pressure should go up. You definitely need some pressure at lower RPMs or you are starving your engine. If your pressure does not change with RPM then there could be a restriction. For example a clogged oil filter will increase your oil pressure. My jeep has 110,000 miles - just changed the oil and filter. I get 30psi at idle and around 40psi going down the road. What you want is flow at all points in the engine.
I have 260,000 plus miles and was getting 37 at idle and 49 at rpm. I changed the pressure sensor because I didn't believe how high my idle pressure was and now get 41 at idle and 49 at rpm (higher than with the old sensor). Recent oil change. It leaks a little but stays on the full mark on the dipstick for over 3,000 miles with some tappet noise at idle when cold. I am using Rotella 10w40 because it has zinc not in standard car motor oil, but still in diesel oil to protect the tappets.
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