2016 4runner Humming / Vacuum Noise

Hey guys,

I've looked everywhere for this issue and can't seem to find someone with the same issue.

I have an audible humming like noise coming from the engine when coming to a stop / when I am stopped. It doesn't continue when I start to drive.

It doesn't seem to drivetrain related, as it continues when I am completely stopped.

It doesn't happen all the time but happens at least once per ~20ish min trip & usually goes away after a little bit of idling, if it was making the noise.

Every once in a while it sounds like air coming out a balloon rather than the consistent hum.

I've taken the car to a shop a couple times to get it diagnosed, 1st time they said it was the brake booster, the 2nd, they couldn't replicate the noise.
Because the brake booster assembly is $100-1500 part and $2600 repair, I wanted to confirm the noise for myself.
I've also tried to go out with a stethoscope, but can't seem to pin point location or the noise stops before I can grab it.

Replaced all idler pulleys except tensioner, new belt, spark plugs less than 10k ago, cleaned throttle body.

2016 4runner, Trail Premium (older version of trd off road premium) with 120k miles

Link to video of noise, turn sound up: https://youtube.com/shorts/XCwF5NJSbr4?feature=share

Anybody experience this kind of noise or have any ideas?

 

Any luck figuring out the noise ? I have a 16 trail and recently started making same noise

 

hey @Yotadude33,

Maybe. I think I narrowed it down to the fuel pump & I replaced that a couple of days ago. I have not heard the noise since, knock on wood, but can't tell if it's totally gone. I'll keep you updated.

I would narrow yours down through process of elimination. You should be able to easily rule out a couple things

 

@papple
Thanks for the reply yea currently trying to narrow it down sometimes does it in park while idling and like you I checked the brake booster and engine bay seems like you can only hear it from inside