Slight knock

[Zullock Holmes]

alright so i was under the jeep today trying to figure out this t case linkage solution and i started the jeep and noticed while under there is a real distinct knock coming from the motor. i tryed to find out where it was coming from and it sounds like it is coming from the lower portion of the engine, cause it's loudest directly under the oil pan.

anyone know what might be causing this

[Wide-J]

Crank bearing? Connecting rod? Lower end noises are never a good thing. Sorry dude. How loud is it with the hood open? Does it run well?

[OTTE]

Crank bearing? Connecting rod? Lower end noises are never a good thing. Sorry dude. How loud is it with the hood open? Does it run well?

x2

How is you oil pressure?

[Magilla]

actual oil pressure not what the gauge is telling you

[CumminsJeep]

only a few things it could be if it's a bottom end problem and steve said them haha. THat would suck dude bottom end problems never turn out well

[Ktmracer419]

cracked flex plate/ lost torque converter bolts can make a noise that sounds like a bottom end knock

[88xjchief]

I have a knock and its been doing it for 20k miles. One day my motor will blow but it hasnt yet and still sounds the same.

[Zullock Holmes]

uuhhhhh.... not really what i want to hear.... at this point in time it's still real light, like you have your head under the oil pan to hear it. the engine runs normal, it feels normal, it's idling normal, i just changed the oil about 100 miles ago...... penzoil synthetic, fram filter, lucas stabilizer, so i don't think thats the problem. it's not overfull, checked that.. and i only put in a total of alittle bit more than 5 quarts, so i know that it's not too much oil. oil pressure sensor is brand new.... reading about 30 at idle and peaks around 50 under heavy acceleration, 40 at normal acceleration. i'm gonna look around and see if i can figure out anything else it could be, and try to better diagnose it.

[OTTE]

Dont 4.0L take 6 quarts of oil?

[88xjchief]

Get rid of the fram. I did have one collapse on my. I only had 5 psi of oil pressure when it happened.

[OWEN]

I would drain the oil and look for a lot of metallic debris in the oil. You can go as far as taking a sample of the oil and sending it to a lab to have it analized but I don't think that is necesary. Possibly take the pan off and check for play between the connecting rods and crank.

I had a 1991 XJ for about 6 months with a ton of miles. It knocked and smoked a little but I drove it everywhere and beat the hell out of it. I planned on putting another engine in it but then I got rid of it. But it never let me down.

[Zullock Holmes]

Dont 4.0L take 6 quarts of oil?

..... i don't know, i just filled it, checked the dipstick, ran it, checked the dipstick again, oil level is fine, it's got like 5 1/2 quarts in it. i don't think that it's going to be that big of an issue though.

thanks owen, i'm probably gonna do that next oil change... pull the pan and everything. as long as the knock doesn't get worse, if it does i'll do it sooner.

[Arundlemcbrundle]

if u have the wrong oil filter on there i've been told that can cause a knock. if your sure its from the bottom end then that sucks but every jeep i've owned has had a knock/tap since i've owned them. i've concluded that its just what jeeps do and have put over 100000 happy miles on them

[clean4drxj]

you do know that the 4.0's are known for loud lifters?, like what was stated check your oil pres... if it checks out good keep driving it all the same....

[Wide-J]

..... i don't know, i just filled it, checked the dipstick, ran it, checked the dipstick again, oil level is fine, it's got like 5 1/2 quarts in it. i don't think that it's going to be that big of an issue though.

thanks owen, i'm probably gonna do that next oil change... pull the pan and everything. as long as the knock doesn't get worse, if it does i'll do it sooner.

Also, make sure you check the oil level AFTER you start it. If the oil hasnt filled up the filter, 5.5 quarts may look like its full if it hasnt been started yet.