Need help oil pressure drops
 

hello everyone im new this forum and recently just bought a 2001 cherokee with 100,xxx on it. the problem is when i first purchased the vehicle the check gauge would go on and drop to zero oil pressure.. my first try to fix was a motor flush and new oil 10w40 it help becuz the car doesnt drop to zero any more but after the car warms up it will drop down to 10 to 13 psi of oil pressure then i decide to change the oil pump and it change nothing it does the same droping down to 10 to 13 psi but im running 5w30 to clean out the motor and i have 10w30 oil waiting to be put in... the weird parts is after i change the oil the first time it never dropped to 0 psi again. the car will build oil pressure while i drive the oil pressure rise a little over 40 psi and stays at over 40 until i come to a stop need help to determind the problem please thank you however helps me out

Did you change the sender?

No i haven't i dont kno what it looks like or even know where it is on the jeep im new to jeeps im not to familiar with xj motor yet

you might have a bad sensor and a small leak in your valve seals causing it to loose pressure.

Sounds right on.

Oil pressure sending unit is down beside the oil filter, has a wire running to it. Shouldnt be hard to find, make sure its plugged in all the way first.

If you are saying that it maintains over 40 lbs when you are driving, and you are running 5-30, and will only drop to 10 13 lbs when idling, I would change the sending unit then put a 15-40 in it and call it good it isn't a new engine, and it isn't meant to run 5-30 oil.

Hey there faudfsp, I drive an '01 as well and have also had oil pressure problems, pretty much do to neglect by the previous owner. I think that the previous suggestion of looking towards the sending unit is a good idea. You could just replace it or you could also, while replacing the sending unit, have the oil presure checked with a mechanical gauge. Just go down to your local mechanic towards the end of the day and see if he won't check the oil pressure with a mechanical gauge for a twelve pack. Then you will know beyond a shadow of a doubt what your oil presure is at. You are at the very limit of what is considered normal operating presures. Also, the suggestion of running 15w40 by the previous poster is a good one. Your motor isn't a spring chicken any more and could use a little more viscosity.

i have 15w40 oil at home the reason way i put 5w30 is to get all the old oil out and ill be doing a motor flush cuz the old oil was really dark ill be changing it over to the new oil once i get the sending unit change and check the oil pressure

You might want to be careful doing engine flushes, especially if you are doing a forced engine flush. Like the one that you have done at the mechanic by hooking it up to the machiene and reverse flushing, if the engine has any large amounts of sludge in there you could dislodge it, break it up into smaller pieces and get that crud stuck in the oil passages. Even the oil flush kit that comes in the bottle can put you in the same boat. Then you will really have something to worry about.:cry:

Just throwing this out there, but I also have an '01 and the oil pressure was doing very simialr things and as it turns out I had a crack head. 0331 head casting that cracked and was leaking antifreeze into the crankcase around 38,000 miles when I bought it last September. Previous owner I think overheated it.
Oil pressure was good after oil changes and after a couple of days would drop lower and lower at idle and the oil level would rise and the coolant level would drop.
Pretty easy to see thru oil cap straight down and look for the signs, milkshake looking oil or white residue. I had a white buildup and an obvious line where the coolant was leaking down.
Good luck, pretty easy head swap though.

I might not do the motor flush i went bought a new oil sender.. but im having trouble find 15w40 oil at the auto parts store i went to autozone and pep boys both didnt have any

Just run the 10w40 then, close enough. Just make sure to replace the oil sending unit and run the car with the oil you have in it now before changing out to the 10w40. Because when you change to the thicker oil your oil pressure is going to increase, therfore if you were to install the oil pressure sending unit and the 10w40 thicker weight oil at the same time, you will not know if you have increased oil pressure do to the new part or because of the thicker oil.