4.0 engine knock
 

Yeah another one of these kinds of posts..
I haven't tore into it yet, just wanted to see what you pros thought..
Here it is.. What ya think..

Well,
I have a 2000 sport. I had a similar 'tap'/'knock'. I pulled the valve cover and started her up. I had poor lubrication through the pushrods. I replaced the lifters and the noise disappeared. I also had oil flying everywhere. 5 lifters were shot, the other 7 were poor performers.
You will hear that replacing lifters without replacing the cam is a mortal sin. It's not, replacing the CAM without replacing the lifters is the no-no. https://www.cherokeeforum.com/f2/roc...uestion-96005/ Have a listen.

What's your oil pressure at idle? Just curious.

I'd pull the valve cover and have another look/listen session. Shoot some more video if you can.

Oil pressure is somewhat stead at around 47-48 at idle. I think that's what I'm gonna do. Pull the cover, see what I can see. Grab a video and ask the pros.

Took off the cover, to take a look.
Some of them are bone dry, even with RPMs up. Some of them are just really slow and poor, a few of them are filled with oil.
Sorry about the squeal, vacuum lines off.
But heres a look with the shop light. I might try to prime them with a little oil, and if it quiets down, that's the ticket..

Before I tear into this too far.. I'm going to give some mystery oil a shot. Maybe it frees things up and gets the oil flowing again.
I have heard good things about it. Worth a shot..

try the MMO I use in my gas as per instructions

Did you see my video? My lifters were shot and the lubrication was just like yours. Each lifter contains two springs. The tiny (I mean baby hair thin) spring was useless and my lifters had corrosion that MMO wasn't going to cure. I would pull each lifter, one at a time to see if you are destroying your cam.
If the lifters look decent, replace em. You will double your lubrication. I wish I had video of my new lifters in action. Do you recall the John Wayne movie where he fought oil well fires? That's how it looked with the new lifters. OIL FLYING OUT.

Looking forward to your outcome.

Yes I did,
And I am glad you posted that.. You were dead on with your diagnosis..
How much did replacing the lifters cost you?
I am on a tight budget, just want to get this thing on the road, until I can afford either a rebuild kit, or a reman engine.

I bought the lifters from Napa, or Autozone. They were 5.50 each. x12.... Around 70 after tax.

If you pull everything, line everything up so everything goes back where it came from. I numbered the bridges with a sharpie before pulling, and I punched 12 holes into a box, numbered those, and placed the push rods into those. It should go very smoothly for you.

I pulled the lifters with a small wire, bent sharply at the end. I don't have a magnet that would fit down there.

Good luck!

Just curious (again)

What's your oil pressure at hot idle?