Rattling noise coming from underneath new Explorer ST!

Ford Guy · Nov 2, 2021

GBVx said:

I have a January produced '21 and same issue. I just had them replaced at a local shop with the Vibrant flex couplings as Ford did not want anything to do with fixing them.
The TSB is nonsense with worm clamps I believe being the recommendation lol.
You need to either cut and weld new flex couplings or replace the entire mid pipe section.
Either or I believe will do the trick. Hope that helps, tks.

GBVx · Nov 2, 2021

Ford is replacing it for me as we speak under warranty.

MikeyP · Nov 2, 2021

GBVx said:

I have this same shudder. When off the gas and coasting at 40 or below I get a rumble or shudder. Goes away when I hit the brake pedal. This has been there since about 1000 miles and didn't change at all with the Thermal exhaust/midpipes. Anything anyone recommends checking out? It's weird because it stops when I press the brake or gas, so maybe something in the pedal assmebly?

I had a nasty loud rattle under the middle of the 2nd row and started when I hit 85ish. That was just a loose heat shield. The dealer said they checked all bolts they could find under the car, and even retorqued all the bolts on my Thermal exhaust, hoping the low-speed shudder would go away. No luck on that one, so I'll take a tech out when I drop the car off in 3 weeks when my passenger headlight comes in (pealing clear coat).

I am annoyed at all these little issues (backup camera, rattles, pealing chrome and headlight clear, drivers cushion clicking around turns) but I did roll the dice on a first-year car and each issue has been fixed when the dealer looks at it. Being just about a mile from the dealer through a nice, woodsy trail makes it less annoying to bring the car in.

GBVx · Nov 2, 2021

MikeyP said:

I have this same shudder. When off the gas and coasting at 40 or below I get a rumble or shudder. Goes away when I hit the brake pedal. This has been there since about 1000 miles and didn't change at all with the Thermal exhaust/midpipes. Anything anyone recommends checking out? It's weird because it stops when I press the brake or gas, so maybe something in the pedal assmebly?

I had a nasty loud rattle under the middle of the 2nd row and started when I hit 85ish. That was just a loose heat shield. The dealer said they checked all bolts they could find under the car, and even retorqued all the bolts on my Thermal exhaust, hoping the low-speed shudder would go away. No luck on that one, so I'll take a tech out when I drop the car off in 3 weeks when my passenger headlight comes in (pealing clear coat).

I am annoyed at all these little issues (backup camera, rattles, pealing chrome and headlight clear, drivers cushion clicking around turns) but I did roll the dice on a first-year car and each issue has been fixed when the dealer looks at it. Being just about a mile from the dealer through a nice, woodsy trail makes it less annoying to bring the car in.

The dealership is linking the shudder to the disintegrating flexpipe. If the Thermal replaced them, I would look at suspension components next. This is inherent to 1st model year vehicles...just like buying brand-new technology...comes with the territory.

GBVx · Nov 7, 2021

Both flexpipes replaced by the dealership, no noise, no shudder, problem solved.

E-Fortes · Nov 18, 2022

GBVx said:

I have an absolutely ridiculous rattle from under the car. It started back over the summer. Someone else posted about it (might have been in this thread?) as well. It turns out for them it was one of the flex pipes. The mechanic at the dealership went on a drive with me so he could hear it, he also owns an ST, which was cool. It was fixed, and that was it. Until a few months later when it started again. Not only am I hearing a rattle at speed 35 and under, which I find to be humiliating on a 60k car driving around in a city where I am sure everyone else can hear it, because I hear it echoing off of the cars parked on the street, but I am also experiencing a resonating shudder when coasting / decelerating down through 40. One of these days Ill take it back to the dealership.

I've the rattle sound in my ST.
I am thinking of modifying it for longer duration. does anyone have any ideas?

AtlasBlue2022 · Nov 25, 2022

When Ford replaces the flex pipes. Are they actually replacing them with ones that won’t eventually rattle or do they just replace them with the same ones and then they rattle again later on? Cuz if that’s the case wouldn’t it just be better to go to an exhaust shop and have them cut the flex portion out and put in higher quality flex pieces?

dman624 · Nov 25, 2022

I had a rattle when I was at a stop, in drive or reverse, while on the brake. Wouldn't happen in neutral or park, but it was embarrassing as F that my new vehicle was doing this. When I took it in for my oil change, it was one of the main things I wanted checked out after the oil change and tires rotated. Dealer called and told me they couldn't replicate the noise, so I told them I would drive myself over to show the tech, but they didn't bite. When I picked it up the next day I haven't heard anything since. My thoughts are they found the issue, fixed it and didn't tell me much about it to keep the reliability crap our of the system. Just my thought

mcfarlrm · Nov 26, 2022

Had my flex pipes replaced due to the rattle under warranty. All was good for a couple months then the rattle came back. I suspect that there were no improvements/revisions from Ford. Worm clamps were also useless. I ended up ordering a Thermal R&D exhaust that includes mid pipes with their own flex pipes. Excited to get it installed next week when it arrives. Replacing the flex pipes with aftermarket is the only way to go to fix the issue.

Cdubya · Nov 26, 2022

mcfarlrm said:

My flex sections didn't just rattle, they eventually failed--not surprising if they are rattling around all the time! The "improved" OE flex sections look exactly the same. I didn't want to waste my time so just bought and installed the Lethal Performance midpipes. Fits a stock system and T304 stainless is a step up from stock.

gkmunch · Jun 21, 2023

Does anyone know when the flex pipe rattle was remedied from the factory? I have a 2022 (Nov 2021 build), and it rattles on cold starts.

Want to check and see if my build should be immune to this before I start poking around under the car. It could always be a loose heat shield from when I installed the rear sway...

jrgoffin · Jun 21, 2023

gkmunch said:

No. They will replace the mediocre pipes with the same mediocre pipes. The only option to fix the rattle is to go aftermarket or have new flex pipes welded in (the Walker 51110 is the one
for the OE pipes). Just had mine done and the difference is night and day. Just too bad the main welder was out sick the day I was there since the job by the back-up guy was mediocre, to say the least. In any case, no leaks and my Gibson axle-back kit sounds amazing again.

DaveG ST · Jun 21, 2023

On my 2020, just had my left side catalytic converter and flex pipe replaced under warranty. My rattle is gone for now. On the new flex pipe the flex section of the pipe has been moved closer to cat converter. I was thinking this was either a design change or the tech was able to make a right side pipe fit, as there is a long wait for getting left side flex pipes.

3widemiddle · Jul 12, 2023

mcfarlrm said:

I have a Platinum that has the same annoying rattle when first started and also at low speed. Will the Lethal Performance mid pipes listed for the ST fit the Platinum also?

hbalek · Jul 12, 2023

3widemiddle said:

There's a recall for catalytic converters and flex pipes which rattle and also cause fumes.

Vetabeles · Jul 16, 2023

Mine just started doing the rattle. Wondering if I should spend the time going thru the dealership or going to a shop to get new ones installed.

Has anybody had issues with the "re-designed" flex pipes?

DaveG ST · Jul 17, 2023

Vetabeles said:

I will try to get a pic of what I think is the redesign of the flex pipe. They moved the flex section forward to possibly have less stress on this part.

DaveG ST · Jul 23, 2023

These are pics of my left side flex pipe that was recently installed by the service department under warranty.

CareerFiremanGuy · Jul 24, 2023

Here's two vids of a Ford mechanic dealing with the flex pipe rattling issue.

In the first vid he's diagnosing the problem and ordering new parts, in the second vid he's making the repairs.

DaveG ST · Jul 24, 2023

CareerFiremanGuy said:

Did everyone notice how my flex section of the pipe has been moved much more forward?

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