undercarrage rattle

[hogv8]

I have a 2004 4 runner with a undercarriage rattle when I let off the gas at about 40 to 60 mph . It sounds like a cable slapping against the frame or under body . I crawled all over under the truck and did find some things that could cause such a rattle and corrected them but the annoying rattle is still there . I thought it could be the spare tire so I removed it , still have the rattle .
Now today it was raining a while driving in the rain , no rattle . Appears to be there only on dry days . Could it be something in the suspension that need lubricating and when it gets wet the rattle stops ?

Can anyone help me find this rattle ?

Thanks , Jack

 

[TRDCal]

I have a 2004 4 runner with a undercarriage rattle when I let off the gas at about 40 to 60 mph

I would look at your exhaust heat shields... although its not impossible I can't imagine a suspension component that would rattle depending on the gas pedal. Normally those rattles come from components related to the engine. Where does it sound like its coming from...front, back, driver side, passenger side??

 

[Burt]

Loose skid plate?

 

[rebelbowtie]

I had a terrible rattle I thought for sure was coming from under the vehicle but it turned out it was one of my cross bars on the roof rack were loose.

 

[20034RunnerV84x2]

Be sure your e brake is off and not sticking.

 

[hogv8]

Where does it sound like its coming from...front, back, driver side, passenger side??

It's hard to tell just where the rattle is coming from but it sounds like about central to rear of the undercarriage . Sometime I think it is wind related because once the rattle starts the tone seems to change some when there is a gust of wind . The rattle does not change according to speed other than it starts at about 40 mph and stops or at least I can't hear it after about 60 mph .

Also I've driven on very rough dirt roads and the rattle doesn't seem to be effected by bumps or even going over a set of railroad tracks , no rattle from the bump .

Like I said before , the closest I can describe the rattling sound is to a cable slapping against the frame or undercarriage but I can not find it.


Thanks , Jack

 

[hogv8]

Be sure your e brake is off and not sticking.

I know the foot pedal for the emergency brake is released but are you saying that it is possible there could be something hanging up at the rear wheels ?

Thanks , Jack

 

[Greydog]

I would say its roof rack cross bars or a heat shield that gets caught by the wind. Although, there are flaps built into the rear corners to ventiliate the chassis, so maybe those too (might also explain the wet weather disappearance)?

 

[oljedi11950]

Heat shield my vote

Those are very small nuts 10mm I believe check those 1st & or remove to see if that is the culprit just 2 !!!!

 

[hogv8]

I would say its roof rack cross bars or a heat shield that gets caught by the wind. Although, there are flaps built into the rear corners to ventiliate the chassis, so maybe those too (might also explain the wet weather disappearance)?

I checked the roof rack thumb screws and they all seem tight . Maybe I'll just remove the cross bars on the rack completely and see what happens . Come to think of it when I bought this 4 runner a month ago the roof rack cross bars were in a different position . I moved them to the max front and rear . Hmmmm

Where exactly are these ventilation flaps . I don't think I saw them while crawling around underneath ?

 

[hogv8]

Those are very small nuts 10mm I believe check those 1st & or remove to see if that is the culprit just 2 !!!!

I did remove the long shield over the exhaust and muffler and also checked all the other smaller shields and they all seem tight enough to not cause a rattle .

 

[hogv8]

This is a true story about a 59 Chevy sedan delivery that my father bought new for his business back in 59 . Right from new there was a clunking noise coming from the rear that the dealer and my father could not detect for a long time . Finally frustrated my dad got real serious about finding what was causing this clunking noise . He was violently shaking the rear of the vehicle back and forth sideways and determined the sound was coming from the right rear fender well . He jacked it up , removed the right rear wheel and somehow part of the right inner rear fender well . Inside he found a 2"x4" x about 10" long standing up inside the inner fender well with a not tacked to it saying " So you finally found it ". I think about this every time I'm searching for my mysterious rattle .

I'm sure I'll find the cause sooner or later . I hope

 

[rebelbowtie]

I checked the roof rack thumb screws and they all seem tight . Maybe I'll just remove the cross bars on the rack completely and see what happens . Come to think of it when I bought this 4 runner a month ago the roof rack cross bars were in a different position . I moved them to the max front and rear . Hmmmm

Where exactly are these ventilation flaps . I don't think I saw them while crawling around underneath ?

It's not the thumb screws that's for adjusting the location of the bars, its the actual cross bar that was loose on mine. There are 4 small torx head screws on the end of each cross bar that holds them in place.

 

[hogv8]

I would say its roof rack cross bars or a heat shield that gets caught by the wind. Although, there are flaps built into the rear corners to ventiliate the chassis, so maybe those too (might also explain the wet weather disappearance)?

As for the roof rack when I first bought this used 2004 4 Runner I saw that the cross bars were both towards the center in the side rails . I didn't like the look so I moved them to the extreme front and rear of the side rails and that seems to coincide with about when I started hearing the rattle but never related it . Yesterday while looking at my owners manual I read where they should be towards the center lined up with a paint mark on the side rails or they could cause a wind noise . I'm wondering now if because I moved them front and rear if this could be the cause of my mysterious rattling sound at 40-60 MPH . I moved them where they should be but haven't driven it yet to see if the rattle is gone . I sure hope this was the problem because I've run out of other causes . I'll let you guys know .

 

[20034RunnerV84x2]

I know the foot pedal for the emergency brake is released but are you saying that it is possible there could be something hanging up at the rear wheels ?

Thanks , Jack

Possibly, especially if you live in an area with high salt or sand usage in the winter. I drove a little with my e brake on ad it made the exact sound you're describing, a cable slapping on the undercarriage.

Drive some with it on, if it is sticking you'll know it because it'll be the same sound. And damage wise, much more can't be done considering its been happening for a while now. And if it isn't the cause, well you know to look elsewhere & not much damage will be done, once you hear it, match the sound and immediately release it.

 

[RAIDN]

I had something similar to this once, the heat shield from directly above the muffler had completely fallen down and was laying on top of the muffler. It was wedged in there well enough that it only vibrated/rattled at higher speeds and wouldn't fall out. As soon as I pulled that heat shield out it was fine.

 

[rebelbowtie]

Also check your exhaust hangars and the rubber isolator that it hangs on too.

 

[hogv8]

I moved the roof rack cross bars to the recommended place my owners manual says and the rattle is still there but it sounds a little different and maybe not quite as loud I think . I don't know what else to try . I guess I'll just have to live with it until I can pinpoint it .

Thanks for you help , Jack

 

[20034RunnerV84x2]

I moved the roof rack cross bars to the recommended place my owners manual says and the rattle is still there but it sounds a little different and maybe not quite as loud I think . I don't know what else to try . I guess I'll just have to live with it until I can pinpoint it .

Thanks for you help , Jack

I've already said it but check your e brake. Not just the pedal, the cables under the truck that run to the rear axel.

 

[20034RunnerV84x2]

axle*