Hi, I need some help with my XJ. So, ever since I went wheeling, I got a hole in my tire, which meant I had to drive on a spare for a little while until I patched it up. But ever since I put my patched tire back on, every time I go into reverse, something underneath in the back makes a ridiculously loud grinding noise. I'd appreciate some help, thanks.

 

check the brakes.

 

I did, they're fine. Is there anything else it could be?

 

manual or auto?

 

it's auto

 

did it start as soon as you put the spare on?

 

No, it started after I replaced it with my original patched tire.

 

Lift it up by the rear axle so both wheels are off the ground.
Let it idle, put it in reverse.
See if you can see where the noise is coming from.

No noise now?
It could be the limited slip diff -if equipped.
Try adding a tube of the diff LSD additive - $10.

 

Yeah, there wasn't any noise after I lifted it. I'll try out your suggestion, thanks!