Bad sound from Transfer case? Video included

[Juukyj]

Ok folks, I’ve got a truck noise and I’ve caught it on

, here’s the info.

 

03 Siverado 1500 LT 4x4 Quadrasteer.

NP8 Transfer Case with the "Auto 4x4" button.

 

I believe the sound is coming from the Transfer case.

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The sound is only noticeable when its freezing cold & after it’s been sitting overnight.

You can hear the sound after startup, when changing into drive gears & while the truck is shifting gears in motion (just for a second before and after the shift).

Once driven about 3 miles and the temp has risen to near 60(in the tranny) the sound disappears.

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There are no changes in performance.

Seem to be no changes in 4x4 operations.

I’ve changes the fluids since the sound started in the tranny(amsoil) & transfer case(auto trak II).

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Advice I’ve been given range from a malfunctioning electric motor on the transfer case or a dry bearing in the case that could fail soon catastrophically.

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Video: Its a cold morning start, the truck is still in 2hi. While someone moves the gear selector between gears I crawled underneath looking and listening. The only thing visible is the front drive shaft try to turn when the gear is changed(odd that it moves while in 2hi).

 

Any Ideas

Thanks!

[gmtech4]

thats a new one on me ,

 

it makes that noise going down the street as you press the 4hi button ? or sitting still ?

 

what did the oil look like before you changed it ?

 

does auto work?

 

and last question,

are you fixing it ?

 

i read it again,THAT IS SHIFTING THE TRANNY INTO DRIVE??

 

get a stethascope and touch various places and do it again,..... i would if it landed on my hoist ,

[Juukyj]

thats a new one on me ,

 

it makes that noise going down the street as you press the 4hi button ? or sitting still ?

 

It does not make the noise changing from 2hi, auto or 4x4

 

what did the oil look like before you changed it ?

 

If anything just a little darker then the new, no abnormal amount of metal on a paper towel

 

does auto work?

 

Yes

 

and last question,

are you fixing it ?

 

The truck is 2000 miles away with my wife working in wintry Idaho, I only had a few days to visit & tinker last weekend. I suppose if this turns out to be major I'll be sending her to a shop. Otherwise it may wait for a couple months.

 

i read it again,THAT IS SHIFTING THE TRANNY INTO DRIVE??

 

Yes, any drive gear and when the tranny shifts from 1-2 in motion. Only while cold.

 

get a stethascope and touch various places and do it again,..... i would if it landed on my hoist ,

 

 

 

 

Your line of questioning has actually got me leaning more towards transmission... hmm... The range selector cable is right next to the transfer case... I wish I was there to dig deeper.

[gmtech4]

shifter cable has nothing to do with it,if it was finished the PRNDL would not line up properly and shifting to park would MOSTLIKELY not happen

 

and yes transmission is the concern,not the t case

 

you have debris in the pan FOR SURE

[Juukyj]

Ok, so hopefully tranny fluid & filter change will resolve it, or at least lead to finding other internal problems.

I'll get working on that.

Thanks!!!

[gmtech4]

changing the oil and filter NEVER ever fixes a GD transmission problem,you are wasting your money but do what you want ,i was a tranny guy for 3 yrs ,but WTF do i know!!!

 

mild rant off !!!

[Juukyj]

For anyone with a similar problem, my chevy dealer diagnosed & fixed the noise!

 

They "guesstimated" it was either:

1. Problem with the transmission filter

2. Transmission pump going out

 

The first step & cheapest solution was a transmission oil & filter change. They noticed no abnormality's during the service. But what ever it was- it's fixed, no noise since!

Amazing the power of a oil and filter change.

[gmtech4]

thats great,

 

im still wondering how the tranny svc fixed it but whateva !!

 

 

lol