1st time being on a forum, I'm having issues with an 01 4.0!! Instead of sinking at in a Lake I would like to fix it!! Replaced oil pump, replaced oil pressure sensor 3 times, still getting check gages light and 0 oil pressure at stoplights!! Curious if anybody has an answer on what I need to do or Could possibly be wrong??

 

Put a mechanical gauge on it and as long as you have 10-13 psi at idle hot and it increases to 40 while driving it, it should be okay. My 00 was the same and I put a Mopar oil pressure sensor on it and the gauge read 10 psi after heat soak, but around 20 as it just reached 210*. I put Shell Rotella T6 5W-40 Synthetic Diesel Oil in it and now it holds 30 after heat soak and 50 at driving speed. This is with only 145K miles on it. It cranked a little slow at -20*F, but I would expect that just from a cold battery! The XJ gets as hot as an oven under the hood because of limited airflow and any venting you can do will help, such as hood vents or raising the back of the hood by putting spacers under the hinges. The ZJs and WJs don't seem to have as much of a problem with heat soak as the XJs do. I heard they designed the body for a 2.5L 4 cylinder, then crammed the 4.0L into it. Makes sense.

 

thank you very much. I'll be heading to auto parts store for mechanical gauge, no oil pressure is scary don't wanna burn up the hot rod lol!!

 

I picked up a Bosch for under twenty bucks just for this purpose. Took me all of 10 minutes to disconnect the stock sensor, plug in the mechanical, and verify that I had good oil pressure, and return it to stock. Ordered a new oil pressure sensor and life was good.

On the other hand, if your mechanical gauge says you have no oil pressure, forget a new pump. Rebuild the engine.

 

Yup as stated verify with a mechanical gauge. If 0 oil pressure it should be making all sorts of knocking sound. I also have a 2000 at 137k and have same issue as Dave1123. I'm pretty sure my head has been replaced due to crack and most likely bearing wore (all from PO) Mine idles hot at 8-9psi (cold around 18-20 or so) and holds around 40-48psi at 2k rpm. All verified with my mechanical gauge and has been like this since I bought 3 years ago...gonna drive it till it gives up. I'm also running T6 15w-40. 15w could be wrong but I'm positive on the 40 but I'm in Georgia so the thicker oil don't bother me.

 

Thanks twenty dollars isn't bad especially for piece of mind, on some other threads I've read it talks about bearings on the cam i believe!??! Is that an easy do it my non experienced self job?

 

thank you, I dont get any MORE noise than the usual noise produced even while sitting for a period of time, lol so it must be pumping something( hopefully) I run the same oil but in washington st. Little noisy on startup up but calms after warm up?!

 

I've never done cam bearings, so can't speak from experience. Looks to me like you'd either have to pull the engine or remove the radiator to get them in and out.

 

Cam bearing are pressed into the block and the oil holes have to align with the passages. It's not too difficult for a novice who knows how to rebuild engines, but it requires special tools to press them in and out. I've done my own on Chevy small blocks, but it's easiest with the block on the bench. With the 4.0, you almost have to have the engine out of the car because the camshaft is as long as the engine and sits low in the block so the whole front sheet metal and grill have to come off and the engine jacked up high enough for the cam to clear the front frame rail. On the Chevys, each cam bearing is slightly smaller as they get deeper into the block and have to be installed in order. IDK if jeeps are the same or not. There is also the end plug inside the bellhousing that must be replaced and can't be done with the engine connected to the transmission.

Personally, I wouldn't run 15W-40 unless you live someplace like Arizona. The only thing bad about Rotella is it only comes in gallon bottles and costs $29.95 per gallon. You'll need 2 bottles to do an oil change and save the 1/2 for the next one. I go 5K on changes and the stuff comes out just changing color a little. Most places that carry it have sales and you can save $10 a gallon when that happens. The one time I didn't hit a sale, it cost me $75 for an oil change including the filter!

Now that I think about it, I may go 10K on changes because I usually put 15-20K on it a year.

Ya know? Back in the 60's when everything had idiot lights, the first thing us young guys would do is install oil and amp gauges on a bracket under the dash. Some guys would put a big SUN tach on top of the steering column and a floor shifter in it. Then put air shocks on the back and the biggest tires that would fit!

 

Thank you very much This information has been very helpful and not the 1st time I've been told to run a lighter oil on start up, We definitely don't have warmer temperatures in the morning!! And as far as cam bearings, Definitely sounds like something I would pay a shop to do!! Hoping the mechanical gauge says I have oil pressure!!

 

Price on Rotella, I usually catch it at Walmart here for around $16-18 on sale.