Humming noise - narrowing down culprit

[chrissurfr]

Hi all,

I have some kind of hum from the truck. I believe its a wheel bearing, but Toyota says its not.

• Its a hum that occurs at 30-40 mph.
• It is not consistent but happens 80% of the time.
• It is the same frequency and pitch and does not sound faster or slower if I speed up or down.
• The rear carrier/diff has already been replaced, and that didn't fix it.
• I have replaced the needle bearing so that isn't the issue.
• The noise occurs in 2wd or 4wd.
• The noise still occurs if put into neutral when driving.

Could it be the transfer case? In my head, all things point to a rear wheel bearing.

Thanks,
Chris

 

[rayofsi]

exhaust parts or loose exhaust shield?

 

[chrissurfr]

exhaust parts or loose exhaust shield?

I'll get under there and give that a look. Thanks

 

[Ogre75]

Alternator bearing?

 

[mteolus]

I can't imagine that it is the transfer case. Have you changed the TC oil yet?

Why did you have the rear diff swapped out? Do you wheel it hard?

And in response to the post above, I had an Escape one time where the belt tensioner wheel bearing went out but it was pretty noticeable at any speed. Check to see if the engine fan is loose? Usually that means you have a water pump going out and would have a fluid leak so I doubt that is the issue.

 

[chrissurfr]

I can't imagine that it is the transfer case. Have you changed the TC oil yet?

Why did you have the rear diff swapped out? Do you wheel it hard?

Well based on the sound coming from the rear/mid-rear the dealer thought that was the issue. Which it was not..

I also did bind the gears a bit in 4wd once. Which is why I was maybe thinking transfer case. But the noise is there when the car is put into neutral when rolling.

 

[Endor-Runner]

get a couple 50lb sacks of corn and lay them in different spots to see if sound goes away. may be something touching a panel might help you narrow it down. i used this trick to hunt down some trim that was vibrating. also try getting someone to drive and you crawl around and try and hear it better.

 

[Jivewalker]

tires cupping? Spiders lubed? Sometimes bad wheel bearings can be identified If you raise and spin a wheel with your hand on the spring. You would feel it as a vibration.

I have a similar hum and it is caused by some cupping on my KO2's from not rotating on time / enough.

 

[thennen]

Wind noise? Wind causing something to vibrate maybe. Mine made a noise in certain crosswinds a year ago or so, but I don’t hear it anymore.

 

[grizzlypath]

I get a pretty good hum going at around that speed. I'm 99% sure it's from my roof basket. I've heard of people using bungees woven between the cross bars to help dampen it. I may look into that at some point. Might be worth checking out. Throw something up on your roof and see if it makes a difference.

 

[chrissurfr]

I get a pretty good hum going at around that speed. I'm 99% sure it's from my roof basket. I've heard of people using bungees woven between the cross bars to help dampen it. I may look into that at some point. Might be worth checking out. Throw something up on your roof and see if it makes a difference.

Good thought. I actually got up there last night and started hitting it on different angles to see if anything was loose.

I'm 99% sure its coming from the passenger rear bottom of the car at this point.

 

[GG5thGen]

Alternator bearing?

I had a similar noise one time in a 98 Chevy Lumina. (Yeah I actually had one)

Turned out to be the serpentine belt tensioner bearing. It finally went out on me on the way to work and had to be brought in on the hook.