At idle (500-800 rpms) when my engines warm my oil pressure is at the mark between the bottom and the 40 I believe. It recently started happening. Checked my oil level and it's full. Pressure is normal upon cold start. No engine knocking.

 

If your oil pressure falls below 10 p.s.i. at idle, you have a problem that could result in engine damage. Normal oil pressure is 30 p.s.i. (+/- 5 p.s.i.). There's a lot of things that could cause low oil pressure, but starting with the most obvious things first:

1.) Is there oil in the engine? Is it up to the "Full" mark on the dipstick? (This is sort of a "duh" question.)

2.) How often has the oil/filter been changed? (I change my oil every 3,500 miles, and the filter every 7,000.) If the oil is black and dirty, then check for sludge/ ash in the valve cover valley. Pull the valve cover. Any crap deposited everywhere? If yes, you are going to need to drop the pan too, and chip every bit of crap out of your engine with a screwdriver, etc.. Vacuum out all the junk with a shop vac. You don't want all that dirt and crap cycling through your oil pump. Check and clean the oil pump screen. Replace it if it's all crudded up.

3.)Once the oil is clean & new, and the oil filter replaced, fire up the engine cold and rev it up like to 2,000 rpm. Any noise? Bearing clatter? What does the oil pressure look like cold? Pop the hood, and with the engine running pull the oil filler cap and look to see if you've got oil being pumped to the head. (You might need a flashlight.) If you don't have oil running in the bottom of the cylinder head valley, I'd say you have oil pump problems.

4.) Screw an external (mechanical) oil gauge into the oil pressure sender hole, start the engine cold and compare the oil pressure as it warms up. If it starts low and stays low, the problem is probably the oil pump. (Replace the screen and pump, check it all again.) If it starts high, but falls as the engine heats up, and winds up being zero or close to it, then it's probably the crankshaft/ bearings ($$$orry, bro.) If it starts out at 30-35 and drops to maybe 10 or so when it's warm, it's probably the sending unit. (They're cheap-- $20 from Quadratec. Replace it.)

If none of that stuff tells you anything, you need somebody smarter than me answering your posts!

 

Clean the electrical connector at the sender real well. Does it have oil on/in it?

What brand of oil filter are you using?

 

Oil pressure spec. for the Jeep 4.0 is this:

*Not less than 13 psi at HOT idle
*Between 37-75 psi over 1600 rpms

If you're in this zone, you're fine. If you're not, you should verify it with a MECHANICAL gauge as you could have a faulty sending unit, inaccuracy between the sending unit and the gauge, etc.

 

mine sits a lil under 20 at hot idle and ive been told thats fine, so your fine.

 

Interesting.

 

Oh good I was around 20

 

Okay I will once it freaking stops snowing!!!!! Too bad I just got my tires rotated or I'd go snow drifting... I've got Wix filters all around.

 

Thanks a lot!

 

Im sittin at about 5 PSI hot at idle and about 19 on the interstate. Installed a new Mellnig MV pump last year to no avail. 250K on the engine. Seems to run ok tho. I keep the oil changes to 5K. Just waiting for her to explode tho.

Still pull those 900 mile trips to Northern Minnesota during the winter just fine.

 

diskman, here's an interesting read on oil pressure:

http://www.jeepforum.com/forum/f19/4...fixed-1304679/

 

Holy sweet baby ray.

 

FIVE p.s.i.? Whoa. Hope you got Triple -A, brother Diskman.

 

Most recent oil change I started running 10-30 Rotella-T Diesel engine oil. Even hot, above 1200 RPM its just barely below 80 and idle barely below 40.
Running regular cheap oil it would usually be a bit under 60 above 1200 and about 30 idle. Always use Wix filters.

 

as per chrysler service information minimum oil pressure is 4 psi at warm idle. and 25-80 psi at 3000 rpm.