Disappearing Rattle Underneath

[2002BlkLTZ]

I've got a rattle that comes and goes. It sounds like it's underneath, driver's side, rear. It *could* be coming from the gas tank area, but all I can gather for sure is it's the rear (from mid-point back) driver's side. It's not my swaybar links, as I've got new greased Moogs all the way around. Last time I heard it, I got all four wheels off the ground and went over the entire under carriage. I pulled, tugged, shook or pounded on everything I could find. All to no avail. When I lowered the thing back down, the sound was gone. It came back again, last week. My dad (a former mechanic) thought maybe a baffle in the fuel tank. Problem is I had a full tank and the tank is mostly composite/plastic, so that's doubtful. It's a hard sound to describe, but it almost sounds like something is loose and swinging back and forth over small bumps under my vehicle. I have been unable to track this down. Kicker is, I'm now down to like 1/4 of a tank, and the sounds gone, it got noticeable less as the tank went down. I'm going to investigate around the fuel tank area more, but wondering if anyone else has any ideas? I *can* reproduce the sound (when it's doing it) by standing on the running board and rocking it, although it takes quite a bit of force. I've also had people watch underneath, even with the vehicle partially jacked up to see if they can find anything. So far, totally stumped. Any thoughts appreciated. :confused:

[2002BlkLTZ]

Wow, looks like no one's experienced this yet. I filled up last night and the sound is back. Looks like I'll have to do some serious investigating to determine the cause. It has to be somewhere around or related to the fuel tank, but for the life of me I can't figure out what it is or might be. :crazy:

[teezee1000]

I have a similar metallic-like rattle coming my Envoy everytime I go over a bump as well, I've taken it to several mechanics and although they can hear it as well, they have no idea what it is. Last week I bought it to another mechanic and he mentioned that my front grill was loose and suggested that might be the sound Im hearing, It is loose, seems one the plastic posts snapped from where it snaps into the frame and it is loose. So this weekend, Im going to remove the whole grill and see if thats the problem.

[2002BlkLTZ]

Update on this problem. I thought maybe I'd solved it over the weekend as it appeared the metal tube portion of the filler-neck was possibly hitting the frame rail. I cut some rubber hose to temporarily insulate this while I could price out a new bracket (some sort of retaining clip which holds the thing off the frame). Upon letting it down off the stands the rattle was still there. I think the next thing I'm going to check out is my shocks. I don't know why the amount of fuel in the tank would affect the sound if it were the shocks, unless it was the added weight in the rear. The problem is certainly getting worse as the days go, so I'm leaning towards some type of suspension part of bushing. I also greased up all the Moog fittings over the weekend to no avail. I don't think my problem is in the grill, it's definately coming from under the rear end. Good luck with your squeak as well though. :yes:

Anyone have any pointers for replacing the rear shocks if required? I've also looked around and it appears it could be the bushings where the shock meets the frame. I've never done any suspension component changes.

[Trailblazin]

I really don't know the technical name for these two small pipes but they might me whats wrong...there should be these two thin pipes that are attached to the radiator plastic casing on the back... when i had my accident, they just bashed in the radiaor with not much precision, so the pipe "holders" were off... my pipes kept on slipping of and rattling....

if u follow these pipes down, u see they meet up with the chassis.. Now one could've come loose and start tapping the other pipe, or in my case, both of them came loose and start tapping everything they touch...

If you don't know where or what I mean, ill take some pics in a bit

[2002BlkLTZ]

Sounds like you're talking about the "cooler" lines for the transmission. My problem is definately on the rear, as I can go over a bump and not hear a sound until the rear axle hits the bump.

[mcouture]

Sounds like my front strut on my 2000 Olds Intrigue. It's a metal rattling sound going over bumps.

Can you produce it by going over bumps on just one side or the other? If so maybe it's shock/spring related?

[2002BlkLTZ]

It's much more noticeable if I hit a bump with the rear driver's side wheel. It will still occassionally make a noise if I hit a bump with the left rear wheel, but I think that could be due to the solid axle. I am going to check some bushings and the shocks and mounts one day this week or this weekend.

[2002BlkLTZ]

I have finally found the source of my squeeking woes. I backed the TB up onto some ramps and got underneath to allow someone else to safely rock the vehicle back and forth. One of the nuts on my Moog swaybar endlinks had come loose. It was getting progressively worse and the stud was moving around in the bracket. I have no idea why early on the empty fuel tank caused the sound to subside, other than there was less weight in the rear as the only thing I usually carry is my 40 pound 6 year old in the back seat.