Mysterious rattle

[Travis]

I have recently noticed a rattling noise coming from the center of the Jeep. I have been investigating this for about a week now and I think I uave ruled out any sort of suspension components making the noise. I crawled under the TJ and tried to move all of the suspension parts, all seems rock solid. I don't currently have jack of any kind so these tests were done with all 4 wheels on the floor. But like I said everything there looked good. The noise is coming from about where the 4WD actuator is, if I put my hand down there while driving, I can actually feel the rattle on the tub. This isn't a persistent noise, it only happens during slow acceleration & hitting bumps while accelerating. Once I get up to speed, say 30mph, the rattling all but stops. It will occasionally make the noise if I hit a bump, but it seems to be more cause by acceleration. I have not had a chance to get back underneath and have a look see, but I figured I would post this for some tips on where/what to look for when I do. Could this be a transmission or motor mount? I have browsed the forum for some knowlege but I am still searching for a line. It is becoming more prevalent and loud over the past week or so, what do you all think it could be? Thanks for reading fellas.

 

[bobthetj03]

Check the trany mount for starters. Also check your exhaust to see if something is close to hitting something else.

 

[Travis]

Check the trany mount for starters. Also check your exhaust to see if something is close to hitting something else.

Went out and check both those areas, both seem to be in good order.

 

[Travis]

Would I have to take the skid plate off to check the trans mount? I think I was looking in the wrong area.

 

[bobthetj03]

Crawl under the jeep and put your hands on the output yoke of the transfer case where the rear driveshaft is connected. move that yoke up and down/side to side and see if you have any excessive play. There will be some play, but not a ton. You can also look at the trany mount where it bolts to the skid while you are doing this to see anything out of the ordinary. Check your motor mounts as well.

 

[Travis]

Crawl under the jeep and put your hands on the output yoke of the transfer case where the rear driveshaft is connected. move that yoke up and down/side to side and see if you have any excessive play. There will be some play, but not a ton. You can also look at the trany mount where it bolts to the skid while you are doing this to see anything out of the ordinary. Check your motor mounts as well.

Ok, I went out and did what you explained. There was no movement up and down in the driveshaft, but side to side seemed to be a bit more than I expected. So yes there is definitely more play side to side than I think there should be. As I was moving it side to side, it actually sounded quite similar to what I hear while driving. The motor and transmission mounts look good.

 

[Germanshepherd]

Ok, I went out and did what you explained. There was no movement up and down in the driveshaft, but side to side seemed to be a bit more than I expected. So yes there is definitely more play side to side than I think there should be. As I was moving it side to side, it actually sounded quite similar to what I hear while driving. The motor and transmission mounts look good.

hi, did this turn out to be your rattle? I am having one too and cant find it for the life of me. mine sounds more like the sounds of pool table balls in the rack, when you jiggle them around in the rack, kind of like that sound but in a rattle style if that makes sense.

everything is tight underneath that I can see. cant recreate the noise by jumping on bumpers, banging everything I can see etc.
thought maybe a bushing but whats odd is it does it more when I go over a rough road with ripples in the road, if I go over a speed bump its not as bad or doesnt do it at all but smaller bumps in road its worse. shop could not find anything either.
the passenger seat does wiggle a lot and makes a similar noise but I was able to eliminate that as the source.

 

[dan lee]

I had the same issue, mine was a transfer case shift linkage bearing, it bolts to the floor board. Next time you drive it and it starts to rattle put pressure down on the 4wd shifter. If the rattle stops, then that's the problem. Easy repair, Crown has a bearing kit. $20.00

 

[Germanshepherd]

I had the same issue, mine was a transfer case shift linkage bearing, it bolts to the floor board. Next time you drive it and it starts to rattle put pressure down on the 4wd shifter. If the rattle stops, then that's the problem. Easy repair, Crown has a bearing kit. $20.00

thanks, will check that out but I think I already checked that when I thought my chirping noise was coming from there but will check tomm when I take it to work. turned out the chirping noise was the rear u joints.

 

[KenR955]

Dan Lee's post is right on the money for my 98.

 

[Germanshepherd]

Dan Lee's post is right on the money for my 98.

Well held done on lever but no difference.

 

[KenR955]

I looked under the Jeep where the 4wd linkage mounts to the floorpan, by your heels when you sit in the drivers seat. Wiggle the linkage up and down. Mine moved about 1/8th of an inch, while making that annoying rattle.

 

[Germanshepherd]

I looked under the Jeep where the 4wd linkage mounts to the floorpan, by your heels when you sit in the drivers seat. Wiggle the linkage up and down. Mine moved about 1/8th of an inch, while making that annoying rattle.

Thanks. Tried that too. Spent probably more than hour and half under neath and banged, pulled on and shook every piece of that jeep. Nothing is loose or making a noise. Only thing I can think of is inside cat converter that's loose.

 

[94c2500]

Thanks. Tried that too. Spent probably more than hour and half under neath and banged, pulled on and shook every piece of that jeep. Nothing is loose or making a noise. Only thing I can think of is inside cat converter that's loose.

If the ceramic material inside the converter is broken up, you might be able to hear it rattle by smacking the bottom of it with the palm of your hand.

 

[Germanshepherd]

If the ceramic material inside the converter is broken up, you might be able to hear it rattle by smacking the bottom of it with the palm of your hand.

Thx. Did try that too but did not hear anything but it may only do it going over bumps but the sound is not a tinny sound like I would assume coming from that. The jeep was in an accident before I bought it so heck, it can be anything. Going to check the inner plastic fender part in wheel wells in case they are loose. I think I checked that before though. So hard to even tell where it's coming from. Depending on which way I turn my head it sounds like it can be coming from anywhere making it even harder to pinpoint. Appreciate everyone input. I'm determined to find it. It's at a pitch that annoys me.

 

[MikeO]

1998 TJ, 4L 3sp. Found this post. I have a rattle as described by many here (metallic drum roll under console). My "clue" to add is that if I lift myself up in my seat and push down on the console, it gets louder. Has to be in gear, with brake on or off. Any ideas? I'm headed out to crawl under and wiggle the suggestions already posted.

 

[MikeO]

I had the same issue, mine was a transfer case shift linkage bearing, it bolts to the floor board. Next time you drive it and it starts to rattle put pressure down on the 4wd shifter. If the rattle stops, then that's the problem. Easy repair, Crown has a bearing kit. $20.00

So, when mine rattled, I pressed down on the 4WD shifter. It did not stop, BUT when I let go, it did. Same thing/problem I assume?

 

[Travis]

I had my front main seal repaired in September, that was the source of the rattling noise, or so I thought. The noise stopped shortly after the repair, but has since returned. I've been under the Jeep, poking around, everthing is tight. It sounds like it's coming from the center of the Jeep, and also other times from the drivers side, front corner. Same sound, but I don't think they're related, as they "feel" different.

@MikeO, I'm not the guy for advice. Hopefully some of the guys will chip in here, and offer you some guidance.

 

[MikeO]

I had my front main seal repaired in September, that was the source of the rattling noise, or so I thought. The noise stopped shortly after the repair, but has since returned. I've been under the Jeep, poking around, everthing is tight. It sounds like it's coming from the center of the Jeep, and also other times from the drivers side, front corner. Same sound, but I don't think they're related, as they "feel" different.

@MikeO, I'm not the guy for advice. Hopefully some of the guys will chip in here, and offer you some guidance.

Thanks Travis, Interesting... I just had my front main seal repaired... AND... had my TC-Drop undone (lifted) as I recently got the SYE and CV driveshaft, so there has been a lot of activity in there. I am hoping Dan Lee is right and it's a "transfer case shift linkage bearing." I'll update here when I know. Mysteries are okay, but not in a Jeep.

 

[dan lee]

Hey Mike,
I know when you lift your Jeep it puts more of a bind on that linkage. I just got done installing a Novak cable shifter, this eliminated that whole assembly. I must say, It is a smooth shift now, going into 4wd Hi-Lo