I've read every thread I could find using google search (site:Cherokeeforum.com "oil pressure")
Most people with low pressure say the engine is quiet, mine is not.
It gets noisy when the pressure drops.
I am preparing to replace the main bearings and rod bearings, oil pump and rear main seal while I am in there.

I've replaced the oil pan and gasket, and the valve cover gasket to stop some oil leaks that started when I first drove it this winter. Oil pickup was clean. Valve train was clean.

 

1989 Cherokee 4 litre
285000 kms
Sat for over 7 years.

 

I will be doing a build thread for this jeep.
I've had it a long time without driving it.
I was finished working on the body about 5 years ago and was hospitalized in a deadly car accident.
This fall I decided I've had enough of looking at it and went for the complete re-do of nearly everything underneath.

 

If it's that far gone the cam bearings will be trashed too:
huge clearance=no oil pressure.
Might as well just yank the motor and do it right.

(You can edit your original post to add/delete info btw.)

 

I need to figure out some of this site stuff, I don't have a computer I only have my phone.

Is the noise at low pressure a sure sign of something?

 

Look inside valve cover when it is noisy...see any oil?

 

Yes. The engine is worn out.

It's a sure sign you are getting ready to spend serious money and time.

 

Under the valve cover looked nice and oiled when I replaced the gasket last week.

I am picking up a Napa gold filter tomorrow to start it and check for oil leaks.
If I am wasting my time trying to fix this engine I will replace it.
I'm hoping it is not screwed and I can save it.
I will be doing all the work myself and I have a garage just for this jeep.
I have a car to drive around in so I have lots of time.

Are the crankshaft bearings the first to give problems?

 

What about cam bearings ? Rebuilt motor not a option?

 

I haven't read into camshaft bearings yet.
A complete rebuild is an option if it is necessary.

After sitting The first week I drove it the oil pan was leaking real bad.
The valve cover was loose and was also leaking.
Everything I read here says get a Napa gold filter.
I've only driven about 400 miles since November when I registered this jeep for the road.
Every fluid has been drained and changed before I drove it at all. The oil was changed when I bought it, and before I drove it. Drained it again to change the oil pan.

I'll find out soon If it is leaking from the rear main seal. If it is and the pan is off it'll be a whole bunch of questions coming.

 

Consider buying a used, but well running, 4.0L. Sitting that long, rattling and no oil pressure spells "complete overhaul". Used engines are fairly easy to come by and all the XJ 4.0s are compatible. The Renix accessories and sensors are specific to the whole thing, so just treat it like long block. Lots cheaper than rebuilding at this point.

 

Gotta pull motor to do cam bearings. Used or rebuild and your done .

 

If I kept the other 1989 or the two 1993's I've had for parts here we'd have a whole assortment of engines to choose from.
limited by driveway space where I rent to keep all the parts jeeps around.
I was driving a 1996 and kept the 1989 I have now in the driveway. All the other parts jeeps had to go. Now I wish I still had one.

 

This engine hasn't cost very much yet.
Besides basic tune up parts plugs, wires, belt, air filter, pulleys.
I've put new injectors, power steering pump, and a starter on that can all come back off.

The jeep itself has a ton of stuff redone. Saved the engine to the last.

 

Reread post #7.

We can see you're still in denial.