2003 2500HD Duramax 4wd problem

Discussion in 'GM Powertrain' started by sarguy, Dec 10, 2009.

  1. sarguy

    sarguy New Member

    I have an 03 Silveraddo Duramax. The t case was toast when I bought it. I had it rebuilt and thought all was fine. When I went to shift in to 4HI while driving there was lots of grinding/noise sounds like it is coming trom the T case. Spoke to a couple of mechanics and they said maybe front diff actuator was bad so bought a new one and installed it. Still the same problem. When sittling still it all engages fine and no noises at all even when going down the road. At low speed it will engage but wth a loud "clunk" at speed only griding. When I have it engaged and going down road can shift from 4HI to 2HI as long as I dont "unload" the front end. Any ideas on what my problem is?
  2. stprovost

    stprovost New Member

    Hello, I always understood that you had to stop, shift to N, and then change 4WD modes.
    Shifting 4WD modeds on the fly may not be a good idea even if you are going slow.
  3. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    If both the front and rear driveshafts are turning the same speed, which they should be if the actuator kicked in, then there should be no grinding at any speep from 2 hi to 4 hi.Since yours is grinding the front driveshaft is not turning at the same speed as the rear. Some other things besides the actuator being lazy are different axle ratios between front and rear because someone installed a miss-matched diff. Or different tire sizes betreen front and rear. I would double check the front actuator and make sure it's not sticking.
  4. Stealth

    Stealth Epic Member 5+ Years 1000 Posts

    Moderator: should this thread be in the diesel section too?
  5. sarguy

    sarguy New Member

    I purchased a new front actuator, installed it , and changed the front fluid. When it is in 4WD and going down the road everything is fine. No strange noises or jerking like you would expect if ratios were incorrect. Any other suggestions?

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