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speedog
02-27-2013, 12:03 PM
Looking for Chev/GM tech for some advice

Basically, we have a 2003 Chev Trailblazer in which we've replaced the transfer case, front diff, had front drive shaft rebalanced, front CV's are good, brakes are good, bearings good and we still have a noise that probably shouldn't be there - from the front end. Not there in 2HI, sometimes in A4WD and definitely there in 4HI. Work was all done in past two weeks due to front diff that blew apart and transfer case that was discovered to have a bearing going bad when being services at the same time.

No codes being thrown, everything works as it should, just a noise that we think shouldn't be there and definitely wasn't there before the front diff blew up. Any contact from a Chev/GM tech would be appreciated.

Twin_Cam_Turbo
02-27-2013, 12:08 PM
This may or may not help you, but if you can't find a tech stop in at a dealer and ask to roadtest with a shop foreman and get his opinion.

corsvette
02-27-2013, 12:45 PM
I had a howl/growl in the front diff on our Denali. A shop rebuilt it with new bearings, this helped a bit but the noise returned. Finally we replaced the gears in it and the sound went away 100%. The gears looked like new but...

I don't know if you rebuilt the front diff or replaced it, something to check anyway :dunno:

speedog
02-27-2013, 12:54 PM
Front diff replaced - suspect that is still the issue.

Twin_Cam_Turbo
02-27-2013, 01:03 PM
Originally posted by speedog
Front diff replaced - suspect that is still the issue.

Replaced with new unit or reman or used unit? Including case and gears?

speedog
02-27-2013, 01:05 PM
Completely new front diff (case and all as an assembled unit) and completely new transfer case

HO2S
02-27-2013, 01:20 PM
All because the front diff in new does not mean that it is good.

Check your tire tread depths. This is very very important. If their are any tires that have more than 2/32nd difference replace all 4. The different tire circumference will cause noise and binding in auto 4wd and 4wd. This will also wipe out t-cases just like you have done already.

speedog
02-27-2013, 01:27 PM
Originally posted by HO2S
All because the front diff in new does not mean that it is good.

Check your tire tread depths. This is very very important. If their are any tires that have more than 2/32nd difference replace all 4. The different tire circumference will cause noise and binding in auto 4wd and 4wd. This will also wipe out t-cases just like you have done already.
How about front sway bar links - can they have an effect?

HO2S
02-27-2013, 02:10 PM
Originally posted by speedog

How about front sway bar links - can they have an effect? Front sway bar links will give you a clunking/rattling noise. Trailblazers also have problem with clunking front stuts. Is the noise a whine or a clunk/rattle?

speedog
02-27-2013, 02:13 PM
Know the sway bar link clunk/rattle noise very well as Trailblazers eat them up faster then my kids can eat ice cream - good thing they're so easy to replace. Just was wondering if worn or broken ones could affect the front drive system and what noises it produces. Also, it's an intermittent whine and pretty much there all the time in 4HI - only there in A4WD upon deceleration for the most part.

HO2S
02-27-2013, 02:28 PM
I think its your tires that is causing a t-case and or front diff noise. It is possible you got a bad ring and pinion but I doubt it.

Tarzan
02-28-2013, 10:49 AM
Since it wasn't there before the new diff it could be the diff. The noise could also be a front wheel bearing that was affected when the axles were removed. Does the noise change when turning left or right at moderate speeds? They also had issues with the early models where the dust seal on the driveshaft passing thru the oil pan made squealing noises but that was rare and you didn't have this noise before. Why was the shaft balanced? Tires are a likely suspect as well and either rotate or change pressure to see if noise moves or changes. For example drop pressure really low like 15 psi and take a slow brief road test on a quiet road.

speedog
02-28-2013, 11:12 AM
Noise is not speed dependent, wheel bearings are good as well as crank case stuff. Will check tires tonight.

Drive shaft wasn't balanced but was straightened.

gram
02-28-2013, 03:18 PM
Does the sound you are referring to sound kind of like a growling? If it does the 4x4 system on these trucks has two parts that frequently go bad and would work in the situations that you have posted.

1) There is a transfer case vacuum switch that is common to go bad or get weak-can let your 4hi only engage partially and will sound like a grumble.

2)Im not sure on the trailblazer but the blazer and jimmy have a diaphram to shift in to 4 hi. On those vehicles it's under the battery (passenger side)-same idea as above.

If you can maybe post a video of the noise it could help a lot.


Good luck

speedog
02-28-2013, 05:22 PM
Thx gram - I would say it is kind of a growl I would say. Some more ideas to check out.

gram
02-28-2013, 07:20 PM
Also this will sound crazy but check your U Joints up front, they usually will make a clanking noise if they are bad but if they are way out of balance it can sound like a growl as well. Very cheap to fix if that is the issue :)

If you can post a video of the noise we can probably get you a quick answer:thumbsup: