• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Rattle under rear of XJ

B

bobinyelm

NAXJA Forum User
Location
Waxahachie, TX
Every XJ I've driven (about 6) have a rattle/knocking I can hear (to varying degrees) when stopped in gear (not in neutral) that sounds like it's coming from the back of the cargo compartment.

It's finally driving me nuts on my own rig-I originally thought it was the exhaust pipe hitting something, but holding it and moving it down doesn't stop it.

Is it something between the gas tank and the cargo floor?

Bob
 
I know of an issue with a rattle occuring due to the T-Case lever on the 231 case... Pressing the lever down makes the rattle do away but when it soon comes back when the lever works its way back up again... That 231 shift linkage needs maint.

George T.
 
My bet is it's either the cat going bad (the internals will start to break apart and rattle inside), a heat shield tapping against the exhaust or the exhaust tapping against something else.

Is there a time where the rattle seems louder? Such as when the tranny is in drive and your foot is on the brake, or when it is in neutral, or when it's in park? My rattles have usually been loudest when I've been stopped at a light and the transmission is still in drive. A good way to track down the rattle in that case is to have someone you trust sit in the jeep with their foot on the brake while you check under the jeep, keeping out of the way of the tires or anything else you don't want to be run over by in case they fall asleep at the wheel.

If you have a rubber mallet, I would bang on the exhaust and see if you can create a similar sound to help you trace down the source.
 
LOL. I'd settle for one rattle. My whole truck sounds like a pit of vipers.

I'd vote for the cat heat shield or exhaust pipe further back rubbing. I have had both. Also on some early years, the cat had a flange that was real close to the crossmember. Any sag at all and it would rattle.
 
Israel said:
My bet is it's either the cat going bad (the internals will start to break apart and rattle inside), a heat shield tapping against the exhaust or the exhaust tapping against something else.

Is there a time where the rattle seems louder? Such as when the tranny is in drive and your foot is on the brake, or when it is in neutral, or when it's in park? My rattles have usually been loudest when I've been stopped at a light and the transmission is still in drive. A good way to track down the rattle in that case is to have someone you trust sit in the jeep with their foot on the brake while you check under the jeep, keeping out of the way of the tires or anything else you don't want to be run over by in case they fall asleep at the wheel.

If you have a rubber mallet, I would bang on the exhaust and see if you can create a similar sound to help you trace down the source.
Click to expand...

I should have said that it ONLY does it when stopped in GEAR, and the BRAKE holding the vehicle stopped.

The parking brake doesn't seem to have the same effect when holding the vehicle against the transmission.

It doesn't sound like a shattered cat (I've heard those), and it sounds like the exhaust banging (so much so I'd have put money on it), but so far I've not been able to duplicate the sound by shaking the exhaust pipe, or banging on anything else. It sounds like it's lightly vibrating against the bottom of the cargo floor (lightly because it's not absolutely constant), but sometimes sound can be bounced around to where it sounds like it's coming from somewhere else.

It seems so common in XJs of various years and in the same conditions (in "D" at idle w/ the foot brakes holding the vehicle stopped) I was thinking someone had the key.

Once the brake is released and the vehicle starts moving at all, the tapping/banging goes away.

Bob
 
You mean your rattle was the rear lift-gate hinge pin? I'll try to shake/tap it, or better yet OPEN it to see if the noise disappears.

I must say that never occured to me!

Bob
 
one of my rattles in my 99 was in fact the exhaust hitting the gas tank heat shield all the way in back, look there. I don't remember, but I think it did kind of sound like it was hitting the floor. I could never get it to move by hand enough to duplicate it, until it got worse however.
 
bobinyelm said:
Every XJ I've driven (about 6) have a rattle/knocking I can hear (to varying degrees) when stopped in gear (not in neutral) that sounds like it's coming from the back of the cargo compartment.

It's finally driving me nuts on my own rig-I originally thought it was the exhaust pipe hitting something, but holding it and moving it down doesn't stop it.

Is it something between the gas tank and the cargo floor?

Bob
Click to expand...

It's the T-case shifter. There's a replacment bushing kit made for it somewhere for $40, you can replace it with a Novak shifter, or you can just give the thing a downward bonk with the palm of your hand every time it starts up. Annoying as hell, On mine i grabbed some old attic insulation and ziptied it around the linkage, worked great for a while but now I hear it tapping just so slightly when stopped in D. Nonetheless its worth a shot.
 
the transfer case rebiuld kit is available through chryslerpartsdirect.com, for 16.00 that's all it cost me and no more rattles, searching for it on the site is a pita but just call them up and they get ya everything you need hope this will help
 
If it is your tc linkage you might consider the Advanced Adapters conversion.
 
I have this same rattle in mine, too. If I can ever locate it, I'll check back in.

I've done the TCase bushing replacement in the past, and this is not the same thing.
 
My 242 linkage rattles in drive with foot on brake, and i have found my exhaust rattling in the two places, the cat flange on the crossmember and also the tailpipe on the gas tank skid or the leaf spring... the latter is due to the cherrybomb i put in throwing the angles of the tailpipe off a hair, if i tweak it just right no noise for a couple of months...
 
Mine rattles only while it is still warming up and stopped in gear. Once it's warmed up, it stops. I'm pretty sure it's the exhaust. Either I'll fix it some day or it will fall off and then I'll fix it.
 
also check to see if the front of the leaf spring is fully intact where it wraps around the front bushing. both of my leafs broke there and the spring only goes around about half of the bushing. thats the rattle i hear currently. new leafs on the way.
 
I have the same problem(2000 XJ 4.0l 183kmi, 2" heavy duty rear springs(it was sagging), 2" spacers in front)

Its something between the floor and the top of the fuel tank, and only rattles when in gear and foot on brake, i cant figure it out, its not the shocks, the exhaust, the heat shield, or any hanging wires or lines. It is very anoying and can be vary loud, i even had my tank out and couldn't find anything, could the fuel pump it self or that evap canister thing bolted to the rear floor go bad and make a noise like this ? its almost as if the fuel tank is pressurized and starts rattling, i might try another fuel cap just to see if its a pressure problem, ill let you know, any other suggestions ?

btw it also get louder if i put weight in rear cargo area

also the same noise can't be duplicated using the e-brake instead of the foot brake

thanks KP
 
You must log in or register to reply here.

Similar threads

T
Diagnose rattle under shift knob?
2
Replies
32
Views
5K
Anak
Anak
M
92 XJ ECU connector
Replies
5
Views
138
Rob Mayercik
R
C
Ticking/Knock/Rattle that matches RPM 88 XJ
Replies
13
Views
2K
PacificEd
PacificEd
1
New Old Member & List of Problems
Replies
6
Views
2K
Unclewolverine
U
G
98 XJ tick tick ticking!
2
Replies
29
Views
5K
straws
S
Back
Top