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21 ST Vibration and noise

RusW1

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2021 Explorer ST
#1
Greetings all,
New guy here, aircraft mechanic by trade, just bought a new/used 2021 ST Rapid Red AWD with 10,700 ish miles. Gold certified Blue seal whatever warranty. Bought it out of town, on the way home noticed a weird noise/vibration at approx 73-77 mph. Wrote it off as maybe turbo noise, maybe a tire, whatever. It persisted so when I took the car in to get the rear end bolt recall done, mentioned it to my local dealer and they investigated. A couple days later they tell me the rear differential has a large amount of metal shavings in it, and they had to replace the entire rear diff. 4.5 weeks later I get the car back, new rear diff, drive it home and same noise. I have a lift so I take it home and put it on the lift and notice grease everywhere! It looks like all the cv boots were leaking and throwing grease, the brand new rear end is covered as well and it shows a path of the grease being flung (sp) off of something with quite a bit of rotational force. Back to the service dept. the next morning. This time the shop foreman goes for a ride, hears/feels the noise vibration, and tells me "yep, there's definitely a problem there". Car has been in the shop another two weeks they are telling me they are replacing one front half shaft, one rear half shaft, and the driveshaft as well. No signs of abuse or damage when I was under the car. Anyone else experienced anything like this? I am appalled at all of the issues, especially since it is supposed to be a Gold certified./ Blue Seal used car.
I ordered a bunch of cool parts for it, but am now thinking I may have bought a lemon. ANy feedback? Anyone else experience anything similar? I'm wondering id this was maybe assembled during the Covid months? I thought about trying to track down the original owner and see if they'd talk to me about their experience, but dont know how to track them down. Thanks for listening.
 

Chamorro85

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Round Lake, IL USA
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'21 Explorer ST
#2
Congrats on the pick-up and welcome!

Unfortunately the drivetrain can be finicky. You'll find tons of threads here with issues like this. Forum is a great place for knowledge and like minded people to come together with similar issues so it's a double edged sword.

The good news and hopefully big takeaway is that the issue is covered under warranty. Not being driven, driven hard, both can cause issue with the vehicle. Don't think you need to worry about lemon law since it's going in for a 'different issue' this time. I'm no stranger to dealer having to take a second crack at an issue because they failed to just take the car for a drive and confirm it wasn't doing the same thing after they threw parts at it. Once they've addressed the issue i'm sure you'll have a new love for the truck. Let us know how it goes!
 

BrooseDaMoose

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East Freetown, MA
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2020 Explorer ST, Silver Spruce Metalic
#3
Welcome to the forum! Sorry to hear about your issues already but as stated, it can happen. I've only owned mine for a year and have had the front half-shaft replaced, the rear differential replaced, the transmission replaced and the AWD module replaced. Some have had the same issues as you while others have have had no issues at all. Just seems to be hit or miss with these vehicles. Good luck and keep us posted.
 

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Chamorro85

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'21 Explorer ST
#4
Welcome to the forum! Sorry to hear about your issues already but as stated, it can happen. I've only owned mine for a year and have had the front half-shaft replaced, the rear differential repplaced, the transmission replaced and the AWD module replaced. Some have had the same issues as you while others have have had no issues at all. Just seems to be hit or miss with these vehicles. Godd luck and keep us posted.
Yeah, my bad. Forgot to mention that I had both front half shafts (axles) replaced a couple months ago. Brought in for one problem (with rear end) and dealer completely ignored me asking about front end since they had it. Was tired of taking back to the dealer twice anytime I brought it to them. Changed dealers and they did a great job.
 

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RusW1

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2021 Explorer ST
Thread Starter #5
Thanks for all the replies, Wow! that is alot of issues. Anyone else getting the "howling" noise I'm experiencing at highway speeds? 63-65 and 71-77 or so? I had the tires checked and rotated, not it. It almost sounds like a wheel bearing but..... Dealer says they have a device that the can use to help isolate the noise while driving down the road, we'll see.
 

hbalek

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#6
Mine had the differential replaced and transfer case replaced twice at 54K miles and I still have shuddering when accelerating. I am taking it back to the dealer on Tuesday to have it checked out again. The front end had both CV boots replaced a couple years ago and earlier this year the front axle disconnect actuator removed per TSB. We'll see what they come up with this time. The driveshaft is still the original.
 

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RusW1

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Thread Starter #7
Took it back to the dealer this morning. They had me take the service supervisor for a ride and duplicated it for him. We'll see.
 

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RusW1

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Thread Starter #8
Greetings all,
Just heard back from my service advisor, they are now looking at replacing the front differential! They used “chassis ears” to narrow it down to the noise coming from the diff. Allegedly no contaminants in the diff but who knows. interestingly enough, both front axles have been previously replaced, at under 11k miles and it has my dealer scratching their heads as to why. Anyone else have a front diff fail? if so what were your symptoms please?
 

hbalek

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#9
Greetings all,
Just heard back from my service advisor, they are now looking at replacing the front differential! They used “chassis ears” to narrow it down to the noise coming from the diff. Allegedly no contaminants in the diff but who knows. interestingly enough, both front axles have been previously replaced, at under 11k miles and it has my dealer scratching their heads as to why. Anyone else have a front diff fail? if so what were your symptoms please?
Mine is back in the shop for noise and shuddering while accelerating. I have previously had the front CV boot/axles replaced, TSB to delete the FADA on the front axle, the transfer case replaced twice along with the rear differential. We'll see what they come up with this time. I'm still under powertrain warranty fortunately!
 

DaveG ST

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#10
As you mentioned, you may want to contact the previous owner. The dealership will have their information. I have traded in a vehicle and received a call from a potential buyer. Tell them you want it for a peace of mind.
 



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