Rattle sound when driving over bumps

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Yuman 1

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Joined
Dec 24, 2020
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7
Location
Yuma, AZ.
First time posting but been following for a little bit. I've got a rattle sound coming mainly from the right front area and occasionally from the left side front. I have a 4" Rough Country lift with adjustable control arms on upper and lower front and rear, also adjustable track bar front and rear. So far I've replaced; ball joints, wheel bearing assemblies, front u joints at the knuckles, new tie rod and ends, new bushings on front and track bar, front shock bar pin eliminators, drop pitman arm (to accommodate lowered frame attachment), new swayer bushings front and rear, new transmission mount. All of these things didn't remove the rattle sound and none of them were really in that bad of condition. My next idea is the motor mounts. Again, really not showing any wear and engine is not moving excessively. The sound happens while driving over washboards, gravel roads and rough pavement. My theory is/was a suspension issue because of when its heard during fast movement of the axel over closely spaced or sharp movement of axel. I've tightened, pried, shook till I can see straight. Nothing obvious to me. Could the motor mount cause the sound and still not present obvious wear? The sound is not metallic metal on metal, it's more like when a shock is loose or sharp thumping. Any suggestions are gladly accepted.
History: 99' TJ sport 4.0L manual trans. Running 33/12.50/ 15 Wrangler Dura Trac tires.I bought the Jeep with the Suspension lift. It has 167k miles, seller said the person they bought it from towed it behind their RV so not sure actual driven miles. It's real clean for it's age and little to no rust. I'm in AZ and it came from Utah.
 
Not seeing any slop or play when I push/pull/twist/shake either shaft. Rear looks like they may have been replaced not long ago. Seller said clutch was repaired before he bot it. Front has some rust so maybe one of those can't see but it's bad situations. Also with 4WD engaged it doesn't change sound. No popping of clanks.
Thanks
 
Welcome!

It sounds like you've inspected things pretty thoroughly. TJs can magnify sounds through the tub, which makes them difficult to diagnose and locate.

I had a similar issue and it ended up being my Savvy motor mount lift. On the passenger side, the lift block's corner was making slight contact over bumps.
 
RMETeeJay said:
Welcome!

It sounds like you've inspected things pretty thoroughly. TJs can magnify sounds through the tub, which makes them difficult to diagnose and locate.

I had a similar issue and it ended up being my Savvy motor mount lift. On the passenger side, the lift block's corner was making slight contact over bumps.
Click to expand...
Thanks I’ve been learning that a sound could be coming from anywhere than were it sounds like. 🥴
 
had a persistent rattle primarily on washboard that I managed to pinpointed to the main fuse box under the hood. drove me nuts until I had the ah ha moment after shimming it with some scrap rubber and the noise was gone.
 
@Yuman1 any luck diagnosing the sound? My 2004 has the same sound (front shocks sound loose) going over washboards. It's very quiet onroad luckily.
 
Check the bolts connecting the down pipe to the exhaust manifold. Easy check is to just shake the exhaust piping the comes down below the engine (don't try this when hot o_O). These bolts can seem tight when they actually aren't. Might also help to hit them with PB Blaster or something similar to get them snugged up.
 
Have you tried tapping on the catalytic convertor with a dead blow hammer?
If it rattles replace the convertor.
Sometimes the honeycomb core breaks loose from the shell and it will drive you nuts figuring it out.
XJ's on rough mountain washboard roads have this fun happen ! Ask me how I know , ( 3 times ):sneaky:
 
Check the bolts in the crossmember in front of the transmission skid with a socket- not by eye. The nutserts spin out and it can appear great and be very hard to find.
 
I once started a thread about noise sources on these-the responses were so varied it blew me away-

dashes

spare tires

mounts

shocks

it was just endless-

Not that they are bad vehicles- but 2 things about them suprised me when I got into them-

1. compared to their predecessors there is way more going on under them

2. to be a high clearance , small vehicle that you can generally see under easily, they can be so elusive to track noises down.
 
Thanks all for the tips! After meticulously checking every bolt in the front end, I decided to move to the rear and found the rear sway bar end link bushings were pretty much disintegrated and causing the rattle noise. Decided to just buy new end links rather than fight finding the right bushings, install was a breeze.

The tip about noise stemming from anywhere but where it sounds was so true.
 
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