So I am having this issue with my Jeep, and I plan on taking it in for service tomorrow at the local dealer here, but thought I would post and see if anyone has any ideas. Here's the problem:

When engine breaking, I am hearing this weird noise from under the Jeep. It sounds like it's coming from the rear, but hard to tell while sitting in the driver's seat. I'm having a lot of trouble describing the sound it's making. It's not a clanking, or a grinding or a binding sound. It's probably best described as a rattling sound, but I don't really know if that's right either.

So here's what I've noticed so far. It only makes the sound when in gear while engine breaking. If I give it gas, the sound immediately goes away. If I press the clutch in, the sound immediately goes away.

The only thing I've done lately was install a new rear bumper, but I've checked it over and it's not making the noise.

Any ideas what could be causing this noise? It sounds terrible and I'm nervous about driving it.

Thanks in advance,
Vinny

 

heat sheild in rear... mine did it to.. removed it goneee......!

engine braking rattles your exhaust pretty good at first..

 

Interesting. I just had the new rear bumper installed and the guy had to drop the muffler to get the bumper on, so it sounds like you are on to something here. I'll take a look at it tonight. Where is the heat shield, between the muffler and gas tank? Any chance you could take a picture for me?

Thanks,
Vinny

 

trust me.. look above your muffler... in the rear.. it looks like aluminum foil... and makes a ton of noise.... just rip it off! hahha it doesnt do much

downshifting creates the exhuast gas's to pulsate alot more.. thus causing the heat sheid to rattle..

that and check exhaust clamps...
i put my mbrp in... didnt even tighten em maybe 25ft lbs... didnt even have a exhaust leak haha just a small rattle...

cranked her down.. quiet as a mouse...

thanks!
cody

 

Awesome, thanks for the info. I'll rip that bitch out tonight and let you know how it works out =)

 

sweet! hopefully its it!

 

ok, so I removed the heat shield but the noise is still there, any other ideas on what it could be?

 

hmmm....check exhaust loose shock bolts... loose driveshaft... loose bolts... anything..

 

Check the heat shield on the cross overpipe, it has 6 or 8 tack welds on it. If you find one thats cracked , pry the shield away abit with a screwdriver. Or you can do like some and put a clamp on it. One of mine cracked and it was doing the same as yours, took me 3 days to find it. That one little weld makes alot of racket. Same thing a couple months later, got under there, another weld broke

 

Turns out it is the rear driveshaft Trying to figure out how I want to proceed at the moment. I talked to someone at northridge and he told me I must do adjustable upper control arms to go with the new driveshaft or my driveline will be at too extreme of an angle. What do you all think? I have a Full Traction 3" economy lift, I was under the impression this wouldn't all be necessary. Also, how involved is swapping a driveshaft if I don't go through the whole rotating the axle to get a better driveline angle, etc.? I've done simple things like installing the lift, bumpers, but am a little weary about swapping a driveshaft or doing any driveline mods as I have never done them before.

Thanks,
Vinny