Rough down shifts on 2010 5.3L LT

Discussion in 'GM Powertrain' started by way2fast59, Jun 19, 2012.

  1. way2fast59

    way2fast59 New Member

    I'm a little stumped here.

    I have a 2010 5.3L Silverado 6 speed Auto with about 49K on it.

    Over the past year or so, I've noticed that the truck seems to downshift really rough when decelerating. For example, you drive up to an intersection, the light turns red, you let off the gas and the truck will "Jerk" as it downshifts into a lower gear. I've also noticed this to happen anytime you pull you foot off the gas and break fast because somebody pulls out in front of you wanting to get slammed.

    Other times, I will be cruising along in a flat open parking lot, let off the gas and experience the hard downshifts. This also happens when you are in trailering mode as well.

    No SES/CEL, or other problems except for the picture attached. This was noticed around last summer when I was changing the oil. It seem that some type of something is leaking around where the transmission meets the gear box (or something like that). I wipe it off every time I change the oil (along with the front sway bar), but it always seems to return. It's never enough to drip on the floor in the garage, but anything leaking on a 2 year old truck is just no good.



  2. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Rough downshifts seem to be a trait of the Hydra-Matic 6L80 6 speed Automatic transmission (MYC), been to the dealership and drove a few new trucks after experiencing it in mine and they all had the same shift trait. Hard to get used to. I'm told most of the reason it does this is due to the freewheeling action that enables it to coast better and return better fuel mileage numbers. If you've ever driven a medium size diesel truck you'll notice it drives alot like that with the downshifting paterns and the engine braking.
    As far as the fluid underneath that definately isnt right and since you shoule still be under warranty I'd have it at the dealership for a look, static leaks like that arent normal and and there shouldnt be anything coming out of any overflows unless theres a problem with something.
    Can you tell if it's Auto trans fluid or engine oil?
  3. way2fast59

    way2fast59 New Member

    Ok, well the truck has been in the at the dealer for two days now. service dept called yesterday and said that it was the rear main seal that was leaking and that they needed to pull the transmission to fix it. I asked how often they have seen this and to my amazement he said only about 2 or 3 over the past 10 or so years. I find it odd that this started actually leaking around 20K. Maybe bad from the factory? Who knows.
  4. Coach24

    Coach24 Rockstar 3 Years 5000 Posts

    Your complaints are consistent with many other owners of these transmissions. I hear of accidents caused by the jerking forward issue. Mine has also experienced a harsh upshift and slippage. But unfortunately when the dealer drives it at 35 MPH for 2 miles they can not duplicate the issue , so it is no problem.

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