rattling, knocking noise

[matus2]

just wanted to put it out there... I am a new owner of a 91 xj with 193k miles, out here in Phoenix, AZ and my xj has the same diesel sounding problem... The previous owner said it has been like that since he can remember, but thanks for the confirmation and reasurance that it is not a major problem that could hurt...

 

[dutchjeep]

Maybe you already did but you may want to check the exhaust manifold. It's very likely cracked (unless this has been replaced). Mine was cracked pretty badly (these manifolds have a design flaw and most of them crack at some point) and after I replaced it the rough idling and dieselish sounds where pretty much gone. Worth a check. Just my 0.02.

 

[sferg]

Another vote for the cat. The honeycomb in mine had broken up and did two things:
1)rattled like you described
2)clogged the cat so bad that it caused my exhaust manifold to crack like
dutchjeep suggested
If yours is in that bad of shape I would highly recommend that you either replace it or gut it (like I did).

 

[allsjeeps]

I had the same exact problem.....turned out to be the cat!!!

me too, it was really annoying and I thought that my jeep was going to expolde everytime. whew!

 

[blakelock]

howdy,

i had a similar rattling noise that turned out to be the transfer case! it was my first 4wd vehicle and i didn't know that i needed to check the transfer case oil. it was bone dry and the gears got completely chewed up. the noise started as a bit of squeaking then became rattling. i never used 4wd but i guess the gear still turn around a bit. i ended up buying a used transfer case from a junkyard and that fixed the prob.

blakelock

 

[ratman572]

Not to be Mr. Negative, but be sure to read my thread.

http://208.101.10.250/~naxjaor1/forum/showthread.php?t=908887

Not to say this is the problem with yours, -but it sure came as one heck of a suprise when my noise (similar to what you're describing) resulted in this.

 

[bburton86]

I could be way off here, but I had a noise driving me nuts for 2 weeks that resembles in some respects what you describe. Mine ended up being the fan (belt driven) hitting the fan shroud. Mine only made noise when driving. On mine, one of the plastic tabs that hold the bottom of the fan shroud in place popped out allowing the fan to contact the shroud at certain rpms. I felt like a real schmuck when I figured out what was going on. Took 10 seconds to fix. Never picked up a tool. Just popped that tab back in place. Hope yours is that easy!

This started for me this week. It took me about a day or two to figure it out. But none of my plastic clips are out. I am sure though that it is the fan hitting the shroud, I can see the plastic being frayed on the shroud. There is nothing loose that I can tell. Not sure how I should secure the shroud.

 

[blakelock]

another possibility is the flex-plate (i think it's called). i previously had the typical rod rattle but it was getting much worse. the increasing noise turned out to be loose bolts on the automatic tranny flex plate. i removed the sheet metal dust cover (pain to squeeze it in and out) then tightened all the bolts. much quieter now.

blakelock

 

[IdeaMan]

I just had this exact problem described in the first post and it ended up being 4 loose bolts on the torque converter. My mechanic took them all out, coated them with Loctite and retorqued. Sound is gone, and worries are gone!