front differential/4wd/4a having issues.

[mrhyne]

hello, i just joined this site. I have a 17 with 277k highway miles on her. It's a 17 EL limited and i have had it since 2,215 miles.

Recently i have started hearing a constant roaring noise coming from the front that seems to be on the driver side. I just replaced the driver side wheel hub to confirm that is not the issue. i have been running the vehicle in 4a and 4h a little over the last few days just to see if i hear variance in the noises. I am convinced the noise is coming from the front diff.
Today, the 4wd sounded like it was free spinning and the roaring was louder and sounded like the 4wd was working but not engaging the half shafts. then it went back to normal after trying three or four times. im pretty new to 4wd stuff. I am trying to diagnose to see what i need to do next! any help is appreciated!

 

[99WhiteC5Coupe]

hello, i just joined this site. I have a 17 with 277k highway miles on her. It's a 17 EL limited and i have had it since 2,215 miles.

Recently i have started hearing a constant roaring noise coming from the front that seems to be on the driver side. I just replaced the driver side wheel hub to confirm that is not the issue. i have been running the vehicle in 4a and 4h a little over the last few days just to see if i hear variance in the noises. I am convinced the noise is coming from the front diff.
Today, the 4wd sounded like it was free spinning and the roaring was louder and sounded like the 4wd was working but not engaging the half shafts. then it went back to normal after trying three or four times. im pretty new to 4wd stuff. I am trying to diagnose to see what i need to do next! any help is appreciated!

Driving the vehicle in 4H can damage the drivetrain, unless you are driving in slippery conditions such as snow, sand, etc.

 

[ediddily]

Did you change a IWE (Integrated Wheel Engagement) hub or the wheel bearing? Is it a grinding or humming noise? If its grinding, lift the wheel off the ground with the car off and try to spin the wheel, if it spins and you hear a click click click click, its your IWE. If it doesn't spin and grabs the CV shaft then its not the IWE. Try grabbing the top and bottom of the tire and try and rock, if it moves in an out or back and forth your wheel bearing may be going bad. If the IWE and bearing feel good, then yes your front differential may need to be rebuilt. When I'm hard on the acceleration while towing I get a humming too as I need to get mine rebuilt. I just changed half the oil in mine after 170K miles (got it with 120k, now 298k). I know its been long over due but its a pain to change without a drain plug. If you do pull the front differential out you may want to think about putting in a limited slip or lunchbox locker in there and put in a drain plug or buy a cover with one. And just FYI, the front differential is always spinning while in 2H waiting for the IWE to be released and grab. So there is a lot of free spin while driving and changing oil is important. Hope this helps.

 

[Dustin Gebhardt]

@ediddily Your last statement is incorrect. In 2H, the IWEs and the transfer case are unlocked. The front driveshaft and the front axles do not spin in 2H. In 4A, the transfercase is locked but the IWEs are unlocked until the traction system senses slippage and then it engages the IWEs. In 4A, the front driveshaft spins all the time, and since the differential is tied to the driveshaft and axles, the front axles also spin while in 4A. In 4H and 4L, the transfercase is locked and the IWEs are locked.

 

[ediddily]

Last time I observed under the car while off the ground, the transfer case was engaged whichever mode it was in. Could my transfer case need rebuilding or something?