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whining/hunning noise


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chandler
New User

Sep 21, 2012, 6:30 AM

Post #1 of 6 (5948 views)
whining/hunning noise Sign In

I have a Mazda Cx7 AWD 2008 with 70k miles. It's making a humming noise starting at about 20 to 30 mph, and gets louder and higher pitched
with increased speed. Puting the car in nutral does has no effect, same noise, same level. Sounds like it's comming from the rear of the vehical.
Seems to be getting gradually louder, although I may just be paying more attention to it. Any ideas would be helpful Thank you.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 21, 2012, 6:39 AM

Post #2 of 6 (5938 views)
Re: whining/hunning noise Sign In

Anything that rotates with speed of the vehicle but high on list would be a wheel bearing. Those usually will be louder or quieter with shift of weight like turns at a speed when you hear it. Can try rotating tires and see if noise follows them or stays the same to rule in or out tires,

T



chandler
New User

Sep 21, 2012, 8:33 AM

Post #3 of 6 (5909 views)
Re: whining/hunning noise Sign In

Thanks T,
Tried the side load / turning at speed, no difference. I've had wheel bearings go bad before and it doesn't sound like that to me.
More of a growl I think. Almost sounds natural, like a gear box or maybe a differential, just to loud. Maybe something to do with
the AWD? Traction control on or off makes no difference either. I'm not too familiar with the AWD on the Mazda, as it is my wife's car.
Thanks again, Steve


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 21, 2012, 10:45 AM

Post #4 of 6 (5899 views)
Re: whining/hunning noise Sign In

First post said to me that load from the engine didn't alter the noise so I'm not thinking gear noises just yet. AWD or NO wheel drive (Cool) the only thing that touches the road is the tires and can wear to make noises and noises can travel making you think it's from one place but source is another. Tricky stuff without witnessing it.

Just carefully look at the tread on the tires. Leading edge of the slots of the treads will wear more than the trailing making a saw tooth kind of pattern on quite a few especially ones not rotated as per schedule listed for the specific car. Some tires just are more prone that others too. If so you can just feel that with your hands. Some can be so far worn into that pattern they really wont recover. If your tires/wheels allow cross rotation and have that they will sound worse and might correct over some time and miles. Repeat 'Might.)

Pay attention as noises are warnings. I'd at least try to rule out tire issues as my experience those can make a speed related noise without much load of weight shifting or acceleration/deceleration forces changing the noise. I really would want to rule that out before blaming gears and gearcase bearing at this point. Lots going on in AWD to differentiate all wheels but gut feeling doubts that so far. If wheels are off certainly check out brakes but "humming" or whining isn't so high on my list for brake issues,

T



chandler
New User

Sep 21, 2012, 10:56 AM

Post #5 of 6 (5896 views)
Re: whining/hunning noise Sign In

Thank you again T, just rung a bell with me, the only thing I've done recently IS add air to the tires. Will definitely check that, I thought they were a little low.
Hope so, much better that a major drive train issue.
Thank you very much,


Steve


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 21, 2012, 12:22 PM

Post #6 of 6 (5888 views)
Re: whining/hunning noise Sign In

Anyone should pay attention to tire pressures. 4X4 regular, FWD regular, AWD sure seem to really want even pressures as manuals suggest and very regular tire rotations. Anything more than 2WD ordinary is really trying to differentiate for arcs of turns, plain turning and harder on tires in about all cases and when safe but 1/2 (example) worn some you can't just buy one or two but need them all! Suppose you could but it's asking too much as 99.? % the car is going straight ahead and all the gizmos aren't doing much that allow non scuffing turning or different wheel speeds for even ABS and so on.

Not to beat that up too much but in a 3 Million buck Bugatti Veyron or a Tata Nano the only things touching the road are the dang TIRES unless you can drive airborne all the time- Hmmm?

T







 
 
 






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