Noticeable whirring noise when under power?

2008 TOYOTA RAV4

150,000 MILES • 4 CYL • 4WD • AUTOMATIC

HUMMUSDUDE

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I'm shopping for a car for my 19-year-old. She's fond of the Rav4 and today we drove 3 different models, 2 had the v6, one the I4, all were "all-wheel drive", model years 2008 or 2009, avg miles was from 147,000 to 174,00.

All three models had the same noticeable whirring/humming noise coming from what seemed like the driver's side rear area. It is definitely not a wheel bearing scrape, or any other kind of metal-on-metal noise. It's got a pitch that increases with vehicle speed, but only when power is going to the wheels. If I take my foot off the gas, it immediately stops, and immediately returns as soon as I re-apply the gas. It is not connected to engine rpm or wheel motion. It only happens when under power. There is no clicking or banging, no whistling like a vacuum leak might do either.

Nov 26, 2022 at 6:24 PM

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JACOBANDNICKOLAS

AUTOMOTIVE REPAIR CONTRIBUTOR
110,190 POSTS

Hi,

I'm not aware of any issues with the rear wheels or suspension. There was a recall related to a rear lower suspension arm. It could be related. Take a look below. It explains the recall.

Although I don't feel this would cause the sound you heard, it may have led to uneven tire wear that is making noise. The idea that you only hear it when you accelerate leads me to think it is related to the powertrain. For example, a wheel bearing, a failing CV joint, or even a problem with a universal joint. But you said it doesn't have that type of sound.

Regardless, what I suggested above is a theory. Not being there to experience it makes it difficult.

Let me know,

Take care,

Joe

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Nov 27, 2022 at 11:18 PM

HUMMUSDUDE

MEMBER
2 POSTS

Thanks for the input. What stands out to me the most is that it was present in 3 different vehicles. I've driven a lot of cars in my life and never heard a sound quite like this. It's more of a hum than anything, definitely not a scrape, rattle, click or clunk, whistle, whine. It's about 1 kHz in frequency, goes up slightly with the speed of the vehicle, is dull and muted sounding, and is a bit louder on one of the three I drove.

Since it's there on all three I'm guessing it's a design issue that shows up in higher mileage situations as no one would buy a new car with this sound. Now that I think of it, it very much resembles a resonant vibration kind of thing, although in my experience that is more commonly associated with specific speed ranges of something in the mix. In this case, it's not engine rpm or mph related.

I'm leaning toward something with the transfer case or transmission, perhaps causing the case itself to resonate while under power? Not sure if that is a thing. Today I'm driving a front-wheel drive model... the teenager is really attached to Rav 4s!

Nov 28, 2022 at 4:02 AM

JACOBANDNICKOLAS

AUTOMOTIVE REPAIR CONTRIBUTOR
110,190 POSTS

Hi,

Anything is possible. I checked to see if there were any technical service bulletins related to a sound and found nothing. If it is in the rear and more of a hum, could it be something like the fuel pump you are hearing?

I'm interested in knowing if the front-wheel drive is the same. If you can, let me know. I'm interested in knowing.

Take care,

Joe

Nov 28, 2022 at 7:34 PM