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wrowzee
11-14-2008, 10:30 AM
Ok,

I bought a 98 suburban about a year ago with 140000 miles, truck did great up until about 2 months ago when I noticed a loud whining noise while driving down the road, it sounded like the rear end was going out. A couple weeks ago I noticed that when I shift the truck into 4Hi the noise goes away.... I got under the truck today and noticed that it acted like the tranfer case was stuck in 4hi and I could not freely turn the front drive shaft. is this normal? I know the front end is unlocked because when I took the front drive shaft out i could turn the input to the front differential but the output at the transfercase was locked in. Any ideas would be greatly appriciated.... Thanks
retired
11-14-2008, 11:30 AM
Set the parking brake and shift the transfer case into neutral and see if you can spin the front driveshaft. If so tranfer case needs a rebuild.
wrowzee
11-14-2008, 05:26 PM
I replaced all the fluids in the front and rear differential and added fluid to the transfercase, after doing all that I can now turn the front drive shaft by hand when the transfer case is in 2hi. When i am going down the road and i shift it into 4hi the noise is somewhat gone. I think the noise is coming from the rear end or the transmission now. it is a really high pitch noise. when I get up to about 70 it is the loudest, but when i let off the accelerator is seems to go away.
retired
11-14-2008, 06:29 PM
If you let off the gas peal does the noise pitch change if so rear diff bearings are shot. Was there any metal inthe rear diff when you serviced it.
CoolAirVw
11-16-2008, 02:48 PM
If you let off the gas peal does the noise pitch change if so rear diff bearings are shot. Was there any metal inthe rear diff when you serviced it.


Yeah, what he said...

A noise that changes pitch on coast and load is usually the differential. Raise the wheels, and jack stand thoroughly, then have a helper run the car and listen to the source of the noise.
wrowzee
11-16-2008, 11:55 PM
Yes, the high pitch noise stops when i coast but starts back when I accelerate. I will try what CoolAirVw (http://www.gmtruckclub.com/forum/member.php?u=21619) said in the next day or so.... when you say bearings in the rear end are you refering to the bearings where the drive shaft goes into the rearend or the other bearings on the output shafts to the wheels? Also when i serviced the rear end there was the normal ammount of metal on the magnet for a truck with 140000 miles, nothing excessive or anything..

thanks for all the help!