horrible low end knock on my 4.0

Well, the jeep sat for a couple months and decided to drive it to the toy run here in Denver. Before i made my trek across town, i stopped and got gas as well as checked my oil. Was a quart low, cool. quart put in. Check oil, everything is on the full mark. Before i put in oil i had a really bad lower end knock that i've never noticed before, which is why i checked the oil. Still really bad knock after the toy run, and when i got home i have a NEW oil leak in the same general area where it would leak if you had a bad rear main.


I haven't had anytime to look at it, as well as I know nothing about the mechanics of an engine. What could i be looking at here? am i gonna throw a rod?
What should i do to diagnose this problem? I've been hearing i have a new 4.0 in my future going into this jeep. What say you?
I've also been thinking if i do have to slap another engine in here, should i do an upgrade. Stroker? refurbished 4.0? ford 302?

Thanks guys.

You sure its the bottom end?

Most knocking noises you pick up after sitting are caused by a sticky lifter.

Check the torque converter bolts (4) before you do anything else. They're notoriuous for getting loose and egging the holes. Sounds EXACTLY like a rod knock. I've had it happen to me.

my starter came loose and had me fooled. knocked like crazy just off idle. i was looking into new engines, until the starter didn't engage on flex plate and i finally checked it out. saved myself a couple grand. typical mechanic tho. no time to fix my own vehicles.

Do you have video? What weight oil are you running? Now that it's colder out it's more common to get piston slap and sticky lifters.

chech the torqconverter bolts I had the same noise and that fixed it.

I have the same knock. I only hear it at idle. I was freaking out until I read about the torque converter bolts, now I just need to make myself check it!

I'll do it when I'm putting the bushwackers on. :moon: