Help diagnosing engine knocking

[Jacksonclouds]

Hello, first I like to say that I’ve always loved jeeps and recently my father past away and left me this one... I don’t really know much about it’s earlier life...
I’ve been trying to search for a similar thread and I know there are thousands about knocking but I couldn’t relate to anyone...

The car it’s a 1998 TJ 2.5 118hp with a little more than 70.000 miles
Since I got it the oil pressure drops to 0 whenever the car warmed up after 15 mins of driving, at first I thought about faulty gauge, but then this noise started to appear over 2000 rpm and only when the throttle is half way, not when realeased and not when fully pressed... it sounds like a cranky metallic noise that relates to rpm...
When stopped with the engine running it randomly gives a knock at the bottom of the engine that reminds me of a clap...

From what I’ve read I thought about: bad crankshaft bearing what can cause the oil pressure drop an the engine noise, but I saw some chain slap similar... and the engine hasn’t got that much miles... I don’t know I just hope I can fix it without tearing apart the hole engine and rebuilding it...

Any thought is going to be highly appreciated and if you think there’s a similar thread or case just tell me no problem...
I’ll post the video below!!

Pd oil from the pan is because I recently changed the oil...

 

[CharlesHS]

What does the oil pressure gauge on the instrument cluster read ?
Do you have a popping sound at the exhaust pipe ?
Might want to remove the valve cover and check the rocker arms for excessive play.
Could be a collapsed lifter....

 

[Jacksonclouds]

What does the oil pressure gauge on the instrument cluster read ?
Do you have a popping sound at the exhaust pipe ?
Might want to remove the valve cover and check the rocker arms for excessive play.
Could be a collapsed lifter....

The pressure gauge reas clise to 3 at the start, but is starts dropping since it warms up, when the car is warm, at idle it reads 0.0 and the check gauge lights up , if you rev the engine a bit is goes to 1.5 , but never more.
Do you think a bad lifter could cause the bad pressure? Or the bottom engine noise?

 

[CharlesHS]

I would check the oil pressure sending unit screwed in near the oil filter to see if it's damaged.
IF the pressure is accurate; then there is a problem somewhere causing that low oil pressure.
The noise you are hearing very well could be connecting rod knock....

 

[Jacksonclouds]

I would check the oil pressure sending unit screwed in near the oil filter to see if it's damaged.
IF the pressure is accurate; then there is a problem somewhere causing that low oil pressure.
The noise you are hearing very well could be connecting rod knock....

I’m going to change it first and I’ll tell you what it does!!

 

[Fishtaco]

The low rev sounds like bearing knock but high rev not so much to me, but I have only ever had 2 vehicle's in my life that developed bearing knock, I wouldnt drive or rev my TJ if it sounded like that especially with the combination of very low oil pressure showing on your gauge,

 

[Jacksonclouds]

The low rev sounds like bearing knock but high rev not so much to me, but I have only ever had 2 vehicle's in my life that developed bearing knock, I wouldnt drive or rev my TJ if it sounded like that especially with the combination of very low oil pressure showing on your gauge,

Yeah... I know it sounds terrible... the car is parked until further notice

 

[Jacksonclouds]

Hello there!! It’s been a while but I’m back, I know people usually use this kind of forums and YouTube just for answers or asking for help but I was hoping to be able to help a little bit in case someone has a similar case… ***(It turned out to be a bad lifter and bad rod bearings)*** , at the end I bought a engine mount and a hoist and took apart the engine myself, it’s the first time but I did it with no problems at all…
I suppose there are many similar threats but I wanted to show how I did it in case I can help someone…
1- I removed the front fender, I suppose you don’t need to, but my hoist didn’t have enough angle and it made the job ages easier….
2- I removed all the engine connections, I taped and labeled all of them
3- Remove the intake and exhaust, it’s not that hard and makes it much easier as well, I removed the alternator
4- Remove the 6 bolts of the gearbox
5 - Remove the engine mounts
(All this comes in many manuals and it’s pretty easy)
The tricky thing for me started with the hoist…, it wasn’t long enough and the engine is pretty small at the back of the bay, I didn’t want to hit the front of the vehicle as soon as it separates from the gearbox, so I attached some ropes to lift the engine and another one connecting the engine with the gearbox, and I let go this one slowly to make the process smooth. I also attached a rope from the hoist to my other Jeep to keep it from moving forward to the car and smash the front bumper…. At the end it was slow but came pretty great!!
When I took apart the engine I found out that one of the lifters as you told me was collapsed, and made the rocker very wobbly.. that was for sure the noise at the top engine… and the noise of the bottom engine plus the list of oil pressure is probably due to the rod bearings being broken and worn out…, it’s all in the YouTube video, I hope that it helps someone and I’ll be posting the results as soon as I rebuild the engine!!