2010 4runner hum/motor sound question.

Danielf

Danielf

New member
I tried searching the web for this but I get gear related topics. Over the last couple of days I've noticed this hum or what sounds like an electric motor sound loud enough for me to hear with the radio on. It won't start until about 40/42 mph and will maintain it loudness no matter what speed I get to. Doesn't get louder as I get faster. Stays the same. Then it just stops immediately once I hit about 30 to 25mph. It doesn't gradually get quieter, it's like a switched is flipped and goes silent. It honestly almost sounds like an ac compressor or some type of electric motor running. But it's winter hear in Az where the temps at 60ish degrees don't require a/c. I even thought it might be coming from the rear but can't tell. I just did an oil change ( just hit 60k) and am going to do diffs and transfer case. Anything ideas what I should look for? Thanks in advance.
 
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Well that's what I thought too. I am running a bajarack standard up too but that never gives me much if any noise till freeway speeds of 75+mph. And the thing is it's not all the time. When I go to work in the am (9-5 job), it does it. But when I drive home, I dint always hear it. I'll try and record with my phone tomorrow but idk if you'll hear it or the high pitch time if my tires. Best was I can describe it is like this... Go to your bathroom and turn in the exhaust fan. Close the door and while it's running go turn in your tv. Now, you hear your tv but there's still this "noise" in the background. Idk.
 
Buts that's the other thing about the wind noise. It STARTS at about 40mph and stays consistent never getting louder or quieter with speed changes until i drop down to 25-30mph and it instantly stops. Nit just "fades", but like I said, turn it on and off just stops. I've even, at speed, thrown in into neutral and let the rpms drop and it still does it. That's why I was wondering if maybe gear related perhaps. Like I said, I just hit 60k. Bought it used from local dealer with 54k nov of 14. So idk bout the maint. That's why I'm trying to knock it now.
 
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Try this, open your sunroof after the noise starts, see if it changes the sound at all.

If not, try opening the roof while you're slowing down, see if it changes the speed at which the noise stops.

If either change it, its the roof rack, you may need to do some sort of wind buffer or plate on the front.

If neither change it, try putting a piece of tape over the top edge of the windshield. Tape that crevice off completely, see if that changes it. If the windshield was replaced in the 4runner, and there's a larger than normal gap on that windshield, its possible you're getting the noise from that area.

The gap on mine is around a ¼ inch, stock windshield. My wife's van had the windshield replaced, same glue-in style as the 4r, and when they put it in, it was slid down slightly lower than the oem glass. Her van whistles and hums from just that slight difference. I have used vinyl to cover it up and the sound is completely gone for a year, right about when the vinyl needs to be replaced.
 
Danielf said:
I tried searching the web for this but I get gear related topics. Over the last couple of days I've noticed this hum or what sounds like an electric motor sound loud enough for me to hear with the radio on. It won't start until about 40/42 mph and will maintain it loudness no matter what speed I get to. Doesn't get louder as I get faster. Stays the same. Then it just stops immediately once I hit about 30 to 25mph. It doesn't gradually get quieter, it's like a switched is flipped and goes silent. It honestly almost sounds like an ac compressor or some type of electric motor running. But it's winter hear in Az where the temps at 60ish degrees don't require a/c. I even thought it might be coming from the rear but can't tell. I just did an oil change ( just hit 60k) and am going to do diffs and transfer case. Anything ideas what I should look for? Thanks in advance.
Click to expand...

My 10 TE had a front wheel bearing go bad. It was making a kind of humming noise starting about 35mph and though the sound got faster it did not get louder with speed. As soon as I dropped below 35 the sound quit. At first I thought it might be a bad fan clutch or something with the transmission. Replaced it and now all is quiet.

Edit: The way I determined it to be a wheel bearing is it would stop when I drove into a hard right turn.
 
Are you using a fairing on the Bajarack? Either way, definitely sounds like part of the rack vibrating at speed. And the pitch wouldn't change once the bar was excited, as the pitch is the natural frequency of the bar that is resonating.

Take some bungee cords and wrap one around each bar on the rack in a helix along the axis of the bars. I betcha that solves it.

EDIT: like this........ https://m.youtube.com/watch?v=sqwLxewsgTI

Dan
 
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00Sebby said:
My 10 TE had a front wheel bearing go bad. It was making a kind of humming noise starting about 35mph and though the sound got faster it did not get louder with speed. As soon as I dropped below 35 the sound quit. At first I thought it might be a bad fan clutch or something with the transmission. Replaced it and now all is quiet.

Edit: The way I determined it to be a wheel bearing is it would stop when I drove into a hard right turn.
Click to expand...

I was thinking the same thing.

OP...You may want to get someone to ride with you so both of you can try and locate where the sound is coming from.
 
Thank you for the suggestions. I have already ruled out the roof rack. Like I said, I know what that sounds like and it's not that. I've heard that whistle/sound of air whipping over the bars and know the diff. It's not coming from up top. The more I listen, the more I hear it coming from the rear of the truck. First thing I thought was ring&pinion. I had a Roush Mustang that i drove like an animal and burned gears up a few times and recognize the sound. But this sounds like a deeper sound hum, not I high pitch gear whine. So
Perhaps it is a wheel bearing. Just seems odd to me. I don't wheel real hard. Just mild overland type stuff like an annual Mojave Road trip and once a blue moon, easy trails. I can't believe only 60k on the clock it's acting up. Huh.
 
And no the windshield has not been replaced. Like I said the roof rack had been up there since last year and this sound just started. And sounds mechanical.
 
Check the push pins that hold the little mud guards in the front fenders near the upper control arms. I had a loose one that made a very similar noise that drove me crazy for a few days.
 
Danielf said:
Perhaps it is a wheel bearing. Just seems odd to me. I don't wheel real hard. Just mild overland type stuff like an annual Mojave Road trip and once a blue moon, easy trails. I can't believe only 60k on the clock it's acting up. Huh.
Click to expand...

Mine hasn't been wheeled hard and has 69K miles on it. The sound was more of a low pitch hum, vrrumm sound than a whine and sounded like it was coming from mid vehicle, not so much front. But it was a wheel bearing... seal was bad, bearings rusty.
 
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