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2004 chevy trailblazer_lt
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Discussion Starter · #1 ·
I'm hoping I can pick the brain of some of the experts here. I'll start by saying I'm far from a car expert, but I can usually tell when something isn't acting the way it should.

It's a 2004 Trailblazer with the 4.2L I-6. A humming/gutteral sound started at high (50+ mph) speeds on the highway a month or so ago. Initially I thought it might be the muffler finally going, but it quiets down (almost to the point where I can't hear anything) when driving more slowly. After some searching on the board, I thought it might be the wheel bearings going, but I jacked up all four wheels (After finding no play with just the front ones) and I wasn't able to detect any movement wiggling the tires at the top and bottom. (Maybe I'm just not experienced enough to pick up a slight wiggle though...)

I have found that it still happens with the transmission in neutral, all my fluid levels are topped off and look OK...but it DOES get much quieter when steering even the slightest bit to the right...which makes me think wheel bearings again...have they just not gone enough for me to feel the wiggle, but are on their way out?

I'm happy to try anything suggested, even if that's to bite the bullet and bring it for a diagnostic to the local mechanic...

Thanks all!
 

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2004 gmc
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Our sealed wheel bearings almost always fail and make horrible noises with the weight of the vehicle on them, and none of this can be detected on a lift or on jack stands. It's so sneaky that multiple people including me :eek: have changed the WRONG ONE. :bonk: :duh: :dielaugh:
 

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2004 chevy trailblazer_lt
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Discussion Starter · #3 ·
Hmmmm. First, props on the avatar...love that show. Second, that's what I was fearing...is it more likely to be the front wheels? And would steering to the right lessening the noise make it more likely to be the left wheel? I saw a pair of wheel hubs on eBay for 120, anyone have experience with the quality?
 

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2004 gmc
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Steering to the right would lessen the force on the RIGHT hub, so the suspect in this case would be the RIGHT hub. But they've been known to fail backwards from that concept.

Cheap bearings are likely to be Chinese knock-offs of unknown longevity. Members have used them, but the long-term verdict isn't in yet, if none of them come back to report.

Personally I would shun them.
 

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2004 chevy trailblazer_lt
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Discussion Starter · #5 ·
Thanks Roadie. I actually just dug up a thread from 2007 discussing a situation similar to mine that talked about the BCA bearings w/ lifetime warranty off eBay so I picked up a pair of them for $130 shipped (unfortunately BEFORE I just saw your reply...but I'm hoping they will be OK).

I'll replace them as soon as they arrive and hopefully I'll be able to mark this thread solved by next week!

Thanks again for the help.
 

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2004 gmc
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Good luck with 'em. See if you can get contact details for the seller OUTSIDE of Ebay so you have more chance of actually collecting on that warranty. :yes:
 

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2004 chevy trailblazer_lt
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Discussion Starter · #7 ·
So I bought the new bearings, put them in (with the help of some newly purchased and still glistening tools.) It turned out to be the driver's side making the noise, but now she's silent again. Incidentally for those trying this after me, it's a good idea to have a large gear/pulley puller that fits around the hub, because though online instructions and the manual suggested just pulling straight off (while being careful not to pull the joint out), mine were almost cemented in there, but came off easily with the puller.

FYI for those looking for a reliable source (from what I can tell after getting the bearings and putting them in):

ebay ID: autopartsdirect2you
Company: Auto Parts Direct to You
Phone: 1-866-770-2771
Warranty: Lifetime
 

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2002 chevy trailblazer_ls
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53 Posts
There is a high dollar machine to detect the origin of wheel bearing noise, but I can't afford it, so I do it low buck style..
I did this on my FWD impala, don't know if it will help TB owners though.. You can get a mechanics stethoscope to do this or use a 2 ft prybar..To detect wheel bearing noise on my car, I put it up on jackstands and let the front wheels hang, then let it run in gear. I take the long pry-bar, put the handle pressed over the flat of my ear tight, then touch the other end onto the lower strut tube/lower knuckle that the wheel bearing is bolted to. You can hear bearing noise loud & clear. Good bearings hum steadily. Bad bearings moan with crackling and a grinding grit sound.. Go back & forth a few times just to make sure, and be very careful not to let the bar slip into the rotating brake rotor/wheel studs..
They wont be damaged, but your ear will hurt like hell..
As for our trucks, I don't know if the 4wd will spin all four wheels with them off the ground, so this may not help..
 

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2003 chevy trailblazer_ltz
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Hey Roadie - do you have to change the hub to change the bearings? I have just aqcquired a "hum" in the front end - 2003 4x4 6 cylinder 122,000 miles. I read about bearing changes and hub changes to elminate the hum, so I am a bit confused as to which to replace or does one inlcude the other.

Also, thanks for the heads up on ebay dealer! This site is great!
 
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