Hey I was wondering if this is somthing major on my Xj, the oil pressure is between 40-50psi when driving but drops to like 18psi at idle when warm. What could be causing it? I'm running 10w40 right now in it. Thanks in advance

 

My 1998 (that I bought new) runs about 40 to 50 psi rpms above idle, and after it warms up it will run about the second hash mark at idle. I don't know what that would be. I believe that anything down to the first hash mark at idle is acceptable and is usually due to the viscosity of the oil. 5w for example. It could also indicate a problem with a main bearing, but what you are describing sounds pretty typical.

If you are not hearing a ticking noise from the hydralic lifters, your oil pressure is probably fine. In fact if you have over 150k miles on the engine and you have never changed the oil sensor you might want to consider doing that. Especially if you have notice any oil pressure gauge erratic behavior.

I think they are less than $40 and super easy to change.

 

Try changing the oil pressure sender. only a couple of bucks.

If that don't work you could do a major cleaning of your rockers and oil pan. Once you engine warms up it may be loosening up some gunk in there that clogs your oil pump screen.

Just a thought. You can try Seafoaming it... Tranny fluid... Kerosene.... Diesel. But that is a lot of oil changes to get the gunk out. And they don't work well if you have a lot of buildup (Sludge) in there.

 

Sounds normal What is the rpm at 18psi? Mine runs 3-5 psi at idle (confirmed with mechanical gauge) and been that way since I owned it.....no tick or knock,yet.
I plan to pull the oil pan and check/replace bearings, if it comes back to 18 psi I will be ticked pink!

 

Dunno the specs for the jeeps engine but the 20 psi range is right for idle usually. and 40-50 psi while driving sounds like everything is good for you.

 

minimum psi is 13psi at idle, 37 plus above 1600rpms.... cant remember how many times ive posted this

 

Factory specs is 13 psi at idle (650). This is used to benchmark clearances in the bearings.....low pressure is not really harmful as long as you have flow...it is the excessive clearances that will cause problems. Some people mistakenly use additivesl to increase pressure but all it does is reduce flow and flow is what you need to get lube to all the bearings. I would not worry about it until I heard some noise. I would use 15-40 wt to compensate for the wear BUT no heavier.

 

Ok thanks for all the help I guess I'll just run it. I remember it was 40 at idle, about 1100rpm but as long as its normal I'll run it I'm just paranoid LOL

 

What brand of oil filters are you guys with low oil pressure using?

 

AC,Mopar and now Motorcraft FL-1 no difference. Oil pan removal is next.

 

Just making sure. See if the relief valve in the oil pump might be stuck.

 

Your numbers are fine and well within the spec listed below. Drive it.

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

 

Thanks that will be on my check list but I think it is a bearing/bearings because I found a small amount of non-ferrous particles in the oil.

 

Im running fram right now, never even thought about that but I remember reading fram is junk correct?

 

I recently put a fram filter on mine and at idle pressure would drop to zero. Changed over to a wix filter and problem went away. Last time I use fram filters.