Originally Posted by EVcherokee

Cob24....as far as I know 40 psi warm at idle, 60-75 psi under load is perfect, but I've heard of some 4.0's that go as low as 15psi at idle and they don't grenade.

Originally Posted by EVcherokee

I'd Seafoam your oil first, and take it from there. From what I can tell ATF is a lot more aggressive than Seafoam and I wouldn't use it unless your out of options. If your lifter is in the process of collapse, you need to do something soon or your valve train will get hammered to death, your rig will start to barely run, and be really hard to drive. Experience speaking

If your a DD remember that a lumpy cam is gonna give you more power, but will usually sacrifice mpg's and driveability. Also keep in if the cam allows for more air, but the intake, and exhaust don't, you will never see the full benefits. I've never cammed one of these motors, but one thing to think about is how the ECM will handle a change in lift and duration.

Whowey....I see where your comin from now!

Cob24....as far as I know 40 psi warm at idle, 60-75 psi under load is perfect, but I've heard of some 4.0's that go as low as 15psi at idle and they don't grenade.

Originally Posted by Bustedback

We have a fleet of Cherokees where I work. Just drive it and enjoy it, it is normal for these engines to make some noise. Your oil pressure is fine and normal. Why change the oil 3 times in 7000 miles? Every 6000 miles is fine for oil changes, you're just pissing money away otherwise. Now if you're driving only short distances and never letting the engine reach normal operating temperature, then you should change it more often.

Originally Posted by EVcherokee

http://www.seafoamsales.com/how-to-u...treatment.html

Click on "Cleaning lifters and oil rings"

The directions tell you to keep checking your oil because Seafoam picks up a lot of carbon, but a good general rule is to just change it at 100-200 miles after putting it in. Don't drain any oil, just add it right in..about half a can for a 4.0. Google is your friend!!

Originally Posted by CommanderXJ

Okay, let me tear it down for you all.

My jeep has this weird tendency to knock after a fresh oil change. This same knock also happens to be there after every cold start. The knocking sound does not last for long, as once it warms up it goes away.

I have owned the car since 109k miles and she now has 116k miles. I have changed the oil a total of three times since I bought it. The first oil change, I put in 10w30 Castrol GTX with a Bosch oil filter. The second time I went up in weight to 10w40 Castrol GTX with a mopar oil filter. The jeep didn't like the 10w40 weight all that much. It idled kind of rough and it was difficult to start on cold mornings. On the most recent oil change, I switched back to 10w30 but I put shell rotella mated with a purolator pure one filter (gold plated oil filter). The car seems to love this oil much more as it idles smoother and drives smoother and the oil pressure is right where I want it to be.

Other than the aforementioned noise, the car runs and drives beautifully and very strongly. Its just the sound it makes when I fire it up in the morning sounds like a knock. And what's weird is that, after I put about 2000-2500 miles after an oil change, the noise on start up isn't as prevalent as it was when it was fresh.

Any ideas? I am stumped...I sure hope it's not signs of the motor going out....cuz I'd be pretty disappointed if the infamous 4.0 flaked out on me at only 116k miles


EDIT: I don't have a mechanic's stethoscope, so I can't verify the source of the noise 100% BUT...I can say that the noise seems like it's coming from the bottom end of the car rather than the top. I guess the range of it would be from the belts to the transmission bell housing....somewhere around that area. I don't know if that would help some.