This started happening a couple days ago but has grown very loud now. It sounds like a loud fast ticking. it doesn't happen in park or neutral even when i rev the engine, I know what a bad flex plate sounds like and you usually cant hear one when you're driving, but my xj doesnt make any noise idling in any gear. here is a video of it making the sound https://streamable.com/npqwzq I appreciate any feedback from anyone as to what it may be? Oil fresh and good level, trans fluid good.

 

That's hard to tell.. can you reproduce it in idle by giving it gas??

The first check would be for exhaust rattle - make sure especially that the down pipe isn't banging against the crossmember. Search for Cruiser54 exhaust rattle and you should find a picture he routinely posts.

The next thought would be something in the accessory pulley area. That would be the second suspicious area.

Also, take care of that check engine light dude!

 

Definitely not the exhaust banging up against something since my exhaust ends right after the 2 pre-cats. I recently replaced my flex plate and torque converter, haven't gotten around to welding the exhaust back on. I cannot reproduce the sound in Park or Neutral while revving the engine. I haven't noticed any power loss, and I know people say the 4.0 is a noisy engine but this tick has gotten loud, I mean embarrassing head turning loud, you can hear it down the street or in another car. The check engine light is for my Torque converter circuit, it hasn't been locking up, the other fault is shift solenoid a but that's all for another thread.

 

Hard to tell, but you sure this isn't the engine pinging under load?

 

I can’t really hear anything on the video, so I don’t know if it’s the same sound I was hearing on mine for a while. I’d have this rattle sound under load and it was driving me crazy, I couldn’t figure it out.

It was the damn fan shroud. I felt like an idiot, I had replaced the radiator and when reinstalling the shroud I had missed the tabs on the bottom where they slot in.

Probably not the issue you are having but I figured it’s an easy thing to check and hey, you never know!

 

It sounds almost like the mechanical fan is hitting something metal when the motor shifts but ive inspected the area and even moved some stuff around and i dont have a fab shroud. Im starting to think it could possibly be a crack in the exhaust manifold and when under load more vibration is cause so that may be the rattle i hear ill take a closer look, not wanting to pay alot for some new headers and cats might try to see if the supposed "crack(s)" is weldable if not ill try the junkyard

 

If it's sounding as you say, it could even be the exhaust parts rattling against something as well... the crossmember thing is the big one, but if your Jeep is in as rough shape as it sounds, anything is possible.

You usually can weld the manifold... at least it's common on the older style ones. If your fan is hitting anything, it's dangerous since the radiator is awful close.

Do yourself a favor and check the motor mounts (and tranny too while you're at it). You can get serviceable motor mounts from Rockauto for like $10/e, they're not hard to swap out with a proper floor jack... might be worth doing... Definitely as easy or easier than welding that pipe (not to say you would avoid that part..)

Regardless, I get the impression (and I could be wrong, no offense intended) that you don't plan on keeping the Jeep all that long or care a great deal about it. IF that is correct, I would ask you do those of us who love these old tanks a favor - please keep us in mind... by that I mean, don't skimp on something easy to save a buck if possible, don't modify it ***** nilly in some way that damages it irreversibly... that sort of stuff. Just a humble request. If I'm wrong, I'll be happy and we're here for you bud.

 

No sir, It sounds a lot worse than what it is. Unfortunately the previous owner was the one who didn't take great care of it, I've been slowly but surely (with my budget) bringing her back to life. I could go on forever on everything I've done to her in the past year. The motor mounts look fine, transmission/transfer case mount is a month old, transfer case is 3 months old. Anyways this afternoon when i was on my lunch break I noticed the sound was completely gone, I even stepped on the gas a couple times to test. Double checked the fans and pullys. My u-joints, wheel hubs and brakes have all been replaced recently so I have no clue what that sound could have been. I don't know if the sound will return, who knows? Thank you guys for your suggestions! ​​​​​​​

 

How can you hear a rattle with open cats? That in itself should turn heads! And no, you can't weld the manifolds because they are cast iron. You may have blown the matrix out of one of the cats and that's why it stopped rattling because it was loose already.

 

I tried smacking the pre cats around, I dont hear or feel anything moving around, there is a bit of side to side play in the exhaust ill have to look more into it on my day off.