Intermittent "buzzing" with engine off

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Sep 4, 2021 | 11:25 AM

KC8RXQ

Thread Starter

5th Wheeling

Joined: Aug 2010

Posts: 48

Likes: 12

From: Grandview

Intermittent "buzzing" with engine off

I have a 2020 F150, FX4, 3.5l Ecoboost at about 3500 miles with an intermittent "buzzing" sound from inside the engine compartment. I was washing the truck and started hearing this sound. I appears to be random but the buzzing comes on and goes off, and then there is a long pause before it starts again. The truck is pointed nose-down a few degrees, the parking brake is set, and I had filled the gas tank prior to washing. I've not noticed this when the truck sits on reasonably level ground.

Does this intermittent buzzing have a source/purpose? Do I need to sit in a lawn chair beside the truck and listen for a pattern to "decode" something? I wish I could attach an audio clip but the closest sound that I can associate the noise with is what you hear on TV from the Emergency Broadcast System, only in short bursts,

Thank y'all and I hope to hear something soon.

Regards,
Ed/KC8RXQ

Sep 4, 2021 | 04:07 PM

Zzoogg

New User

Joined: Mar 2021

Posts: 17

Likes: 8

FYI. I park mine nose down daily on a very steep driveway. Never heard anything. Mine is a 2020 with the 2.7

Sep 5, 2021 | 12:39 PM

HeavyDutyMechanic

4wd High

Joined: Sep 2021

Posts: 9

Likes: 3

Just throwing out some possibilities here. Is the cap on your coolant reservoir tight? Does it sound like a vacuum pump? It could also be some kind of on board diagnostic that the truck is running after it turns off. On the equipment that I work on we generally have to install kill switches on them to kill all power. I always advise people to never kill the power to a piece of equipment for at least 5-10 minutes after shutting it down. There is still a few things going on even after you turn the key off.