I would say I had a defective oil pump for at least 1,000 miles.
Stupid me thinking "its okay I have a bad oil pressure sender, my oil pump is new"
Yea that was wrong.

I have yet to remove any crank caps, But I know what to look for. Thinking a mircro polish is going to be the least I will do before I go ahead with new bearings.
Anyone know where I can find the OEM specs for crank measurements?
I want to make sure this Jeep lasts as long as possible.

After an oil pump failure for unknown mileage I think its a solid idea to go ahead and assume I have to replace my main bearings, and rod bearings.
Anyone have any suggestions as far as what brand?

 

What year? 4.0? How low did your oil pressure get? Any engine noises?
You might take a good look at the piston skirts while the pan is off too.
Clevite is a respected bearing manufacturer, tough to go wrong with their stuff.

 

Just a few more things to add to Radi's post. How do you know you have a bad oil pump??? Did you verify the oil pressure with a mechanical pressure gauge??? Just guessing that you have a bad oil pump wont get you anywhere it will just empty your wallet.

 

Sorry I dont know how I forgot that,
2000 4.0 175k.
Honestly I am not sure. I assumed (made an *** of myself) that my oil pressure was good because it was a brand new crapa (napa) oil pump.
I drove the car for at least 30-50 miles with little to no oil pressure depending on how well my OPD was able to turn that mess of an oil pump shaft. (see the picture below)

What am I looking for on the skirts?

Thanks for the name drop Im going to look into their products

 

If you had zero oil pressure you wouldn't have made it 50 miles and the lifter noise and bearing thump would be obvious. I'd guess the pump was still turning some if the motor was quiet. How low did your pressure gauge get?
You really don't need much pressure to avoid damage, some engines (chrysler 3.3, 3.8 for example) run about 5# at idle, the warning light doesn't come on above 2#.

Pull the main and rod bearing caps- if you have a spun bearing you'll know it, they have a clearly worn smeared appearance. If you see any sign of bearing trouble you'll also want to inspect the crank, rods, cam and cam bearings and valvetrain too.
OTOH if nothing's spun, you might be just fine rolling in new bearings, checking clearance with plastigauge and buttoning it back up.

Pistons- as long as the pan is off check the skirts for cracks. A strong light and magnifying glass helps, at least for old farts like me who can't see, lol. Minor cracks turn into missing chunks given time and it's a known weak spot.

 

Hard to say considering I wasnt driving the car for a week. Car makes various sounds hard to say what was the motor if any.

My Oil pressure sender is broken, and yes I understand now why thats a bad idea to have a broken one. My idea was brand new oil pump why should I worry.

Will do Im going to check that tomorrow when I get a chance.

Should I consider a micropolish at least?

Also will check for this thanks alot! Will report back asap. 10 hour days 6 days a week dont give me alot of free time.

 

"Crapa"...really? AFAIK, NAPA oil pumps are simply relabeled Sealed Power, which is a well known brand.

 

Agree. The pump was probably turning intermittently. A motor can run quite awhile at low load just on the residual oil. Remember those infomercials for oil additives where they drain the crankcase and the engine runs for over an hour? Well what they don't tell you is that is normal,additive or not. 40 years ago out of boredom we took an old Fiat engine and drained the oil out of it and wired the throttle wide open. I cannot remember exactly how long it took for the motor to seize but it took several cigarettes and almost a six pack!

 

Sometimes rod bearings are the first to go. More than once I've changed the rod bearing inserts only because I had an engine "on the bench" (or in the back of a Chevy truck once).

Last I looked they were $20 at Rockauto for our Jeeps, but I prefer to shop locally at my Napa.

You might Google "plastagauge" .....also the bearing should be stamped on the back after you pop it out. If the crank had been turned it might say .10 for example. (or Std). Or .60

It's almost surely standard, but you always need to check.

It's my .02 that the mains on the 4.0 are one of the last things to worry about.

 

if you didn't hear any knocking odds are it's ok. I'd check the bearings just to be sure. I had the sane issue with a melling pump I put in an old truck. however, that old sbc valvetrain let me know it had no oil pressure.

 

With the pump removed, check the condition of the oil pump drive gear on the camshaft. If it's badley worn out the camshaft needs to be replaced.

If you pull connecting rod caps and see that the bearings/crank journals are worn, the cam bearings are probably trashed as well. The engine needs to be pulled to change all the cam bearings.

Check the piston skirts in the full down position for scuff marks in line with the piston pins. If the skirts are scuffed on both sides of the pistons, the piston in the pin area is probably going to fail. Scuffing of the pistons in this area is usually caused by a lean running (hot piston) condition.

Check the cam bearings for bearing liner extruding out.



If all of the above is okay, with the piston full down, see if you can fit a .003 feeler gauge between the piston skirt and the cylinder bore. If it fits, the piston to bore clearance is excessive.

 

On some of the late model blocks like 2000 and up, there is a surface where the oil pump mounts that is not machined like the earlier models.

Hence, an oil pump seems as if it's tight when in fact it is not seated well and doesn't seal to the block. The other problem is that the pump sets cocked and breaks the tangs on the drive.

 

I have no reading at the gauge but the oil is splashing out of the rods and into the rocker pivots on idle so i think i have pressure.no noises from lifters. any guesses?running fine,i drive easy,too.

 

You definitely have oil flow. If it is getting to the rockers it is getting everywhere else.

 

Probably a bad Oil Pressure Sensor. Try using a direct reading pressure gauge to check the oil pressure. You can rent (refundable deposit) gauge from the auto parts stores.

P.S. You should start your own thread on this.