I just got a Hummer H2, 2006 base unit, SUV....when I push the button for either 4WD High or 4WD Low you can hear a LOUD meshing of gears noise, not a "grinding" noise but a loud clanking noise. The vehicle drives fine in normal 4WD, 4WD High, and 4WD Low...no noise at all while driving in each one of the 3 modes. The loud noise occurs only when you change modes of the transfer case. Is this noise common or is it something I need to be worried about. Thanks for any comments regarding this. jsIII

 

Well I know in my 2009-2 LUX suv, The manual talks about having the rig moving about 1-2 or 3 miles per hour or rolling before you change Hi to Low. You don't want to be going fast when you do it just slightly rolling so the gears can mesh easily. Not sure about your 2006 but I would look in your owner's manual under that section ....or shifting the transfer case.

You don't want to damage that unit $$$$$$. Check out your manual or try rolling slowly as you push the button. It will clunk when it drops into low but not grind.

CHECK THE OWNER'S MANUAL

 

That sound is actually pretty normal. As mentioned above, moving slowly, we're talking walking speed here, helps it to engage. But yeah, the first time you hear one of these shift it is unusually loud for a transfer case.

 

L.O.L. Yep Scared the Poop out of me... Bang!!! Yah got to love the HUMMER....Leaks ...Noise...and Handles that pop off and More.

 

Service your TCase way more often than recommended. Its only 2 quarts, I switched to 5w-30 synthetic motor oil. The Borg Warner 4480's series can get expensive to replace planetary gears, sprockets, chain, etc. Oil is cheap. These units are engaged full time AWD (Denali & Escalade), unlike a Tahoe or Yukon.

 

I change mine every oil change.... As you mentioned, 2 quarts isn't much. I would be a little bit leery of running 30 weight oil in it. I stick to Dexron 6.

My 2003 H2 is under 120,000 miles.... But our 2014 Escalade is getting close to 180,000 miles. They both get the fluid changed in the transfer case with every oil change. No issues at all on either. The Escalade version has less to go wrong with it. It's a simple one speed transfer case, missing a lot of the internals you find on the H2.

 

Thats what all the remanufactures recommend in all non-clutch t-cases. It's a little thicker and much more temperature resistant than dexron6. There have been cases allegedly where the t-case gets so hot it evaporates the dexron6 and blows itself up. In fact, the remanufacturer of mine won't warranty it if you dont run 5w30. If you're changing every oil change tho I don't think it matters.

 

Good points...........I did mine for the first time at 50k per the manual with the Tranny (2009). And I change oil every 6 months Mobil 1 5W30. Use to off road when the 2 was young.. but after a few years I stopped. Lots a work to get it ready for Off Roading..Changing Tires and whatnot.

Anyway, I drive it about 7 K a year. Only has about 78K on the clock. So, I think you got something there. So since I.m low milage do you think I should go with Dexron 6..or stick with what the manual suggest. I forget what they recommend? My 2 only sees local traffic and the occasional NJ Parkway or the AC Expressway.