Newest Gallery Photos

  1. Chevy Truck Forum

    Welcome To!

    The #1 Chevy Truck Forum Online

    Online since 2004, we're the #1 Chevy Truck & SUV user community. If you have any questions about your Chevy or GMC Truck, SUV or Crossover, or just want to connect with other GM owners and enthusiasts around the world, you've found the best place on the internet to do that.

    Join Today ~ It's Free

    Registering is Free and Easy! Do it today and we'll see you on the forums soon!

Leaking Autotrac

Discussion in 'GM Powertrain' started by dcriffle, Feb 4, 2010.

  1. dcriffle

    dcriffle New Member

    What would make fluid leak from the two rear speed sensors on a 2000 silverado, 5.3 transfer case? If it is the vent, the hose disappears up in the rear engine bay. Thanks.
  2. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    The first thing to do is pull the fill plug and see if it's overfull. If it is you may have a bad seal between the transmission and transfer case. If it is overfull it will blow fluid out the vent. If not the speed sensors will leak because the o ring shrinks over time.
  3. gmfreak

    gmfreak New Member

    I haven't seen sensor o-rings leak that much, but I have seen many snap rings inside the rear case half wear a hole in the rear case, it will be on the right side half way up.
  4. dcriffle

    dcriffle New Member

    Thanks for the advice, guys. I checked the vent and it was clear and the fluid ended up being about 13 mm low. I cleaned the case and filled it with Autotrac II and we'll check it again later and post it. I read (somewhere) that heavy towing will blow some fluid, can't remember where though.
  5. sc99z71

    sc99z71 Rockstar 100 Posts

    Is that True??? Whenever I tow my travel trailer (~5k-5.5k) after a lond drive there is "fluid" on the tow chains and anything hanging low behind the truck. I have never been able to find out what the heck is going on. I dont have any leaks (none that I know of), and the "fluid" on the chains never smells like oil. Could what you were saying about the autotrak fluid blowing out during heavy towing be my mystery problem, and if it is, is it a problem?
  6. sc99z71

    sc99z71 Rockstar 100 Posts

  7. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    Your transfer case should never blow out oil under any circumstances. If it does you have a major problem!

    Usually when oil is seen after heave towing it is coming from the transmission because the transmission is overheating. A hot torque converter is what makes the oil vent out and blow back. The reason the torque converter gets hot is because towing in overdrive with a heavy foot keeps the torque converter from locking up.
  8. sc99z71

    sc99z71 Rockstar 100 Posts

    I always tow in 3 and never in D, even on the interstate (~60-65mph). This will be the first summer of towing the camper with the new shift kit, so we'll see how she does.

Share This Page