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Discussion Starter #1
I have a weird hum that comes and goes while I'm at highway speeds. I can be driving down the freeway with the cruise on, and it'll all of the sudden appear. It sounds like there's a car with no muffler driving directly next to my driver's door. It changes pitch with speed, and as I slow down on an exit ramp, the frequency of the hum gets longer, almost like it's the brakes or something. However, tapping the brakes at freeway speeds doesn't help or make it worse.

First I was thinking tire balance, but I'm baffled since it's so intermittent and can get so loud! I noticed it the first time when I was towing two snowmobiles, and thought it was just hitch vibrations, now it's happening without towing anything. Have had an alignment done since it first started.

Any ideas??
 

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Re: Weird intermittent humming noise...

I'll bet it is the carrier bearing for the drive shaft.
 

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Discussion Starter #3
Re: Weird intermittent humming noise...

6Sixathome said:
I'll bet it is the carrier bearing for the drive shaft.
Would that by chance be covered by the powertrain warranty?? I'm at 36,600 miles...so maybe they'd work with me under b2b. If not, how do you diagnose and how hard is it to change out?
 

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Re: Weird intermittent humming noise...

bloc0102 said:
Would that by chance be covered by the powertrain warranty?? I'm at 36,600 miles...so maybe they'd work with me under b2b. If not, how do you diagnose and how hard is it to change out?
Read here http://www.gm.com/total-confidence/vehicle-warranty/?brandId=gm&src=sch

I would think that it is covered. I've changed them before on an old pick-up and it was'nt too bad, not sure how it would go on an OUTLOOK.
 

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Re: Weird intermittent humming noise...

6Sixathome said:
Read here http://www.gm.com/total-confidence/vehicle-warranty/?brandId=gm&src=sch

I would think that it is covered. I've changed them before on an old pick-up and it was'nt too bad, not sure how it would go on an OUTLOOK.
Thanks! Gotta be honest though, I'm seriously considering selling this thing after having steering gear replaced, strut mounts replaced, sunroof replaced, transmission cooler leak, PS leak........and now this all by 36k!

Think the 2011 Acadia's are any better? I love the Lambda and get GM supplier pricing.
 

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Re: Weird intermittent humming noise...

bloc0102 said:
Think the 2011 Acadia's are any better? I love the Lambda and get GM supplier pricing.
Yes I do, and if you can get out of decent enough than go for it :thumb: It's too bad that they are worth 3K to 5K less than the same ACADIA :sosad:
 

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Re: Weird intermittent humming noise...

Take a look at your tires; check the sidewalls to see if there is any bulging. You may have a cord inside the tire that is broke. I had this happen on my Taurus; made the same sort of sound until I blew the tread off the right rear tire at 70 mph. The shock of the tread separation jarred the fuel cut off switch and made the engine shut down...............just an idea :-\
 

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Re: Weird intermittent humming noise...

AA/78U said:
Take a look at your tires; check the sidewalls to see if there is any bulging. You may have a cord inside the tire that is broke. I had this happen on my Taurus; made the same sort of sound until I blew the tread off the right rear tire at 70 mph. The shock of the tread separation jarred the fuel cut off switch and made the engine shut down...............just an idea :-\
Thanks...did it come and go? Drove around yesterday with no issues. It's definitely gone more than it's there.
 

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Re: Weird intermittent humming noise...

bloc0102 said:
Thanks...did it come and go? Drove around yesterday with no issues. It's definitely gone more than it's there.
It started out that way; the noise would come and go. Eventually the noise was constant and I could never figure out what was causing it till the tire let loose. I'm not saying this is your exact problem; just putting in my .02 :thumb:
 

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Discussion Starter #10
Re: Weird intermittent humming noise...

AA/78U said:
It started out that way; the noise would come and go. Eventually the noise was constant and I could never figure out what was causing it till the tire let loose. I'm not saying this is your exact problem; just putting in my .02 :thumb:
Just thought of something, I've rotated my tires since it started, and it still sounds like it's in the same spot. Does that eliminate this possibility?

Hauling the snowmobiles 400 miles this weekend, we'll see if it gets any worse.
 

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Re: Weird intermittent humming noise...

If the problem is actually in the tire; then the sound should "move" with the tire rotation. Let us know how the tow goes this weekend
 

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Re: Weird intermittent humming noise...

AA/78U said:
If the problem is actually in the tire; then the sound should "move" with the tire rotation. Let us know how the tow goes this weekend
The noise came about 10 miles into the trip each way, and only lasted for 5 miles or so. On the way back, it was fine until I had to hit the brakes, then it immediately started. It was also definitely worse when I was on the brakes, but still went away after about 5 miles.

So, could this be brake related? Could something be sticking? Or maybe hitting the brakes reasonably hard shocked whatever is making the noise into making noise...
 

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Re: Weird intermittent humming noise...

check to see that theres no rocks stuck around the rim/brakes/rotor.
Sticking caliper.
Wheel bearings.

as for the rock. Once crossed at a muddy crossing- where my Trailblazer sank into the mud (on a roadway)- tires were into the thick mud about 1/3 way up the tire.
Finally crossed.
Once on the road again- while braking- you could hear a harsh grinding sound...
checked- and round a rock up agains the rotor.
 

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Re: Weird intermittent humming noise...

Maybe the best thing to do is take off each tire 1x1 and do a through look see.
 

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Re: Weird intermittent humming noise...

Could be brake related... remember when in Drive (vs. 'L') the brakes are applied when you let off the gas, a.k.a "Brake Assist", so it could be a slightly warped front rotor. I had to replace mine @ 28k miles, but than again, you can typically feel warped rotors through the steering wheel under braking.

During this event, are you getting any feedback through the steering wheel?
 

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Discussion Starter #16
Re: Weird intermittent humming noise...

XRDreamliner said:
Could be brake related... remember when in Drive (vs. 'L') the brakes are applied when you let off the gas, a.k.a "Brake Assist", so it could be a slightly warped front rotor. I had to replace mine @ 28k miles, but than again, you can typically feel warped rotors through the steering wheel under braking.

During this event, are you getting any feedback through the steering wheel?
Really? What about when the cruise is on? I do notice a very slight wobble in the wheel while under braking, but inspected the rotors ~5k miles ago and they were fine. I do not get any feedback in the steering wheel while the noise is present; I do not notice anything different when it's there vs when it's not.
 

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Re: Weird intermittent humming noise...

actually when in D- and going downhill- there will be descent control- which uses engine braking/trans to help slow the vehicle. Youll see the RPM's go up etc. Thats why many people report they cant 'cruise' down a hill without the RPM's going up.

When in L- this feature is turned off. so its easier to just cruise down the hill....
Now-- if it is a LONG hill with no traffic- cool-- cruise on down with safety.
If its a long hill with twists/turns/traffic- I recommend you leave it in D- this will allow the engine to do its engine braking- and help keep your brakes cool to avoid brake fade.

The Lamdbas do not have Brake assist/ hill assists-- that will hold the vehicle (say at a stop on a hill) while you move your foot from brake to gas.
 

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Re: Weird intermittent humming noise...

rbarrios said:
The Lamdbas do not have Brake assist/ hill assists-- that will hold the vehicle (say at a stop on a hill) while you move your foot from brake to gas.
I stand corrected... it has "Panic Brake Assist", not "Brake Assist", and the fore-mentioned Hill-Descent. Probable cause: a late night and too much :beer: at Happy Hour.

You say you inspected the rotors... with a run-out gage? If you do get a slight wobble only with the brakes applied, odds are good you have a "warped" rotor (vs. an out-of-balance wheel). The "warped" rotor, as exhaustively explained on the StopTech website, is a rotor that has developed high spots of brake material which cause the brake pads to not ride flat on the rotor surface.

Could it be your problem? Maybe so, maybe not...
 

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Discussion Starter #19
Re: Weird intermittent humming noise...

XRDreamliner said:
I stand corrected... it has "Panic Brake Assist", not "Brake Assist", and the fore-mentioned Hill-Descent. Probable cause: a late night and too much :beer: at Happy Hour.

You say you inspected the rotors... with a run-out gage? If you do get a slight wobble only with the brakes applied, odds are good you have a "warped" rotor (vs. an out-of-balance wheel). The "warped" rotor, as exhaustively explained on the StopTech website, is a rotor that has developed high spots of brake material which cause the brake pads to not ride flat on the rotor surface.

Could it be your problem? Maybe so, maybe not...
I did not use a run-out guage, don't know if the dealer did or not when they rotated the tires and I asked them to check them out as well. I've had the very slight wobble for 5k miles before this started happening. I would say it is a possibility, but it was only the last time that it happened when I applied the brakes. Every other time it comes while I'm cruising down the highway and the brakes didn't make it worse. Maybe it's gotten worse to the point that the brakes will now cause it? Just weird that it comes and goes like that, like something has to get to a certain temperature for it to happen and any time it's cooler or hotter it doesn't do it. It also only happens at freeway speeds.

Hasn't happened at all this week, but I've just been going the 8.5 miles to and from work.
 

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Re: Weird intermittent humming noise...

bloc

what is the outdoor adventure package as listed in your signature?
 
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