Ok so long story short my motor in my 97xj went packing after 275,xxx miles. So I found a 94xj that someone was selling for parts with 16x,xxx miles on it. So I swapped motors. I put in a new oil pump, plugs, wires, water pump and thermostat. After I swapped them I started it up and it ran smooth and wasn't making any noise. About 10min later it sounded like it missed and started making some noise. I shut it down immediately. I only started it a handful of times after for no longer than a minute each time. So I dropped the oil pan and everything seemed fine. There was no metal or anyting in the oil and all the pistons were getting oil. I noticed the timing chain seemed pretty loose so I changed it and the new one was way tighter. So I went to start it back up and it started making the same noise again. It sounds like a knocking sound and gets louder when you rev it up. I'm just looking for any help that might lead me into the right direction before I do a full rebuild or go another direction. Thanks for your time.

https://youtube.com/shorts/zvi1T4oApls?feature=share

I couldn't get the video to upload because it said invalid url but I copied a link to the video. Thanks again.

 

Oh Boy... This is something I know about...In 1994 I ordered a new XJ with the "High Output" 4.0....I picked it up from the dealer & drove it home 14 miles....I opened the garage door & pulled it inside....I couldn't believe the noise coming from the engine...I immediately checked the oil & it was full.....I called the dealer & told them about the noise, they said bring it back...I argued they should send a flatbed, they said no, it will be fine ( I guess they knew already)....I drove it back & they gave me a loaner after briefly listening to the noise......Several days later they said the noise was internal & they would have to remove the engine & take it apart....I refused... I told them I didn't buy a brand new vehicle to have an engine torn down & fixed like a used car...They said they would get the Chrysler Rep involved....A meeting was set with the Rep & owner of the dealer, we went back & forth...They finally agreed to give me a new Grand Cherokee with a V-8.... in exchange, I refused, I said if I wanted a V-8 Grand Cherokee I would have ordered one....My XJ was a Dk green Sport with an off road pgk, roll up windows, tow pgk & a few other selected options, It was not something a dealer would order for dealer stock.... So there is stayed & I was in a 2 year old loaner... At the end the dealer said if I brought it in for service regularly, they would personally warrantee the engine for as long as I owned the vehicle regardless of mileage....Something about piston slap, & modifications to make it a "High Output" .... I wholesaled it about a year later with 7000 miles...What a disappointment, I'm sure there are some on this forum who know exactly what I'm talking about.....I bought a used 1996 2 dr SE with a 5 speed, that I ran to 235k & it was a quiet as a church mouse, Chrysler got their act together & fixed their mistake meantime I took a blood bath for their incompetence ....Unlike todays 5.7 Hemi, another disaster with the cam & lifters starving from oil, from a faulty design that there doing nothing about.... That's my sons headache...getting off topic....With regard to the above posting its likely one of those Diesel sounding High Output 4.0.....

 

If it's an auto trans, make sure your flexplate to torque converter bolts are tight.