2017 S550 Bad Rattling Sound - Cannot Diagnose

[shiparino]

Reaching out to see if anyone has had this issue. Started hearing this terrible metal on metal coming from the rear side passenger/trunk area about 6 weeks ago. I finally started digging in yesterday. I removed the rear seat, package tray, rear quarter side cover (both sides), right side passenger seat belts (front and rear), right side overhead airbag and mount, everything in the trunk... all one item at a time, then road test. I even got in the back while my neighbor drove around but couldn't pinpoint it. It sounds like metal flexing and/or tapping against metal or even glass. I was looking for a broken spot weld and figured I could at least apply pressure and get it to calm down. This car has hit some kind of reliability wall after 8 years, everything is crapping out..

If this sounds familiar, I'm open for suggestions. Right now I'm driving around with a totally stripped-down interior, looks super jenky.

Thanks

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[SheepDog]

Check the rearward differential bushing mounts.

 

[shiparino]

Check the rearward differential bushing mounts.

Thanks, I'll take a look. It really sounds like it's coming from inside. Did you have this problem?

 

[SheepDog]

Thanks, I'll take a look. It really sounds like it's coming from inside. Did you have this problem?

I don't, but many have. When the bushing breaks, the bolt/sleeve now contacts the subframe and can make rattling or vibrational noises. Just something to check.

 

[shiparino]

I don't, but many have. When the bushing breaks, the bolt/sleeve now contacts the subframe and can make rattling or vibrational noises. Just something to check.

I'll check it out, but I looked at this online and that sounds like a deeper "clunk" tone. Mine is a higher pitched rattle.

 

[shiparino]

This is not my car, but found the noise on Youtube. They say it may be the shock mount. 2016 Mustang GT Rear C Pillar Rattle

 

[Oakley]

Thanks, I'll take a look. It really sounds like it's coming from inside. Did you have this problem?

don't bother with stuff like that. if it sounds like its coming from a spot weld inside the car its probably from a spotweld inside the car.

people are going to give you ALL kinds of wacky suggestions but what you need to do is get someone to ride in the back of the car and listen.

with my car the noise was repeatable if i pushed down on the rear of the car with the trunk open.
it got worse in hot weather
anytime that corner of the car took any load (acceleration, braking, turning) it would make the noise.

the body shop supposedly went inside the decklid and trunk area and just beat the hell out of it with some wooden dowels until it quit making noises.

i can still hear something sometimes from that corner but its so random and quiet it doesn't bother me like the other sound.


i just hammered and bent all of the spot welded parts enough to either seat them full or relieve tension.

 

[stang17]

I know that exact sound and recently added an entire box of Kilmat to help eliminate it.
The two of the most common culprits are the rear passenger airbag mount as well as the black box in the passenger rear side trunk. I unscrewed the box in trunk, taped piece of foam padding on it, and retightened it. Sound 90% gone after doing that.
My sound was repeatable at around 2,250 to 2,600 rpm in any gear. It sounded like a mechanical buzzing/tapping sound.

 

[stang17]

This is the black box I'm referring to. It was loose and resonating against the metal that is is bolted to. I wedged a piece of foam in between the box and metal before retightening it.
Helped get rid of most of the sound where I can only hear it if radio is off and I'm trying to hear it.

 

[shiparino]

This is the black box I'm referring to. It was loose and resonating against the metal that is is bolted to. I wedged a piece of foam in between the box and metal before retightening it.
Helped get rid of most of the sound where I can only hear it if radio is off and I'm trying to hear it.

Yes, I added a piece of steel to strengthen that floppy box. Did not change anything. I've been thinking about adding sound deadening material, but I know that won't fix it, just cover it up some, like you're reporting. The sound is loud and crisp, sometimes metal on metal, sometimes like metal on glass. As for the airbag mount, I really thought that was the culprit, but I removed it entirely and no change. Maddening.

 

[gtppmt]

I think I have the same problem. Mine is coming from the rear driver’s side - it happened frequently in February when the weather was colder, but haven't heard it lately. It occurs when I’m driving, particularly on uneven pavement. It sounds like it’s coming from the trunk area. I re-torqued my rear suspension parts but didn’t find any loose bolts. However, my rear end link ball joints were bad, so I ordered new parts. Not sure if that will fix the problem

 

[shiparino]

I think I have the same problem. Mine is coming from the rear driver’s side - it happened frequently in February when the weather was colder, but haven't heard it lately. It occurs when I’m driving, particularly on uneven pavement. It sounds like it’s coming from the trunk area. I re-torqued my rear suspension parts but didn’t find any loose bolts. However, my rear end link ball joints were bad, so I ordered new parts. Not sure if that will fix the problem

Yeah, I re-torqued the suspension parts last night. Nothing loose, nothing broken, nothing worn. My noise doesn't go away, but at speed on a smooth freeway, it's not bad. Now that I have the whole interior stripped out, it sounds like something is breaking every time it goes off.

 

[shiparino]

I saw another string about this issue where someone had found a rock lodged between the outer and inner body skin, accessed behind the wheel arch cover. Today, after weeks of this incessant sound and driving around since Sunday with no interior in the car... the sound seemed to stop. Maybe I just needed more coffee, but if that's the case, the rock theory seems plausible. My broken spot weld (theory) wouldn't just fix itself and there's no interior to support the broken insulation rubbing on itself theory. I'm hopeful, but we'll see in about an hour when I hit the road. haha

 

[shiparino]

Well... I guess I just let the noise win. Removed the inner wheel well cover, some dirt and small pebbles, but no smoking gun. Tired of driving around with no interior, so I just added sound deadening material on all the exposed metal (had a roll for another project car) + I shoved a pillow in the cavity behind and above the right rear wheel well. Put everything back together and though I still do hear the tap, tap, tapping, it is 90% more quiet. Most passengers won't notice it. Still, it's very unsatisfying to not figure it out.

 

[stang17]

I was really rooting for you!

I can understand the frustration all too well. A buddy and I had mt car up on lift, dropped rear IRS, exhaust, driveshaft , gutted interior, went through every bolt, fastener, connection, bushing. Put a different exhaust on with all new clamps. Spent entire weekend trying to find it to no avail.

Ended up using kilmat and some foam here and there to get rid of "most" of it. If I ever find the definitive solution I'll report back.

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