2008 silverado coolant flush

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by afireinside, Jun 7, 2009.

  1. afireinside

    afireinside Member

    Cant find this info..... looking to do a 100% coolant change on my truck to rid myself of dexcool. But where is the drain plug on the engine block for a 4.8L????
  2. DrewsZ71

    DrewsZ71 Rockstar 100 Posts

    I hate to tell ya but there isn't a drain plug on the engine block to drain coolant. You could remove the expansion plugs (freeze plugs for the old timers) to drain it but its definitely not recommended b/c it'll be a nightmare to reinstall those things without them leaking. I have lots of experience with that...lol. Also you might wanna check with a gm dealer if you havent already to make sure it wont void your warranty. I know when I used to work at the dealer GM told us they wouldn't cover it. It might be different now but better to be safe than sorry. By the way, why do you want to go back with the old stuff? Did you hear something bad about dexcool?
  3. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    The easiest way is to remove the thermostat. Drain the radiator and start the truck. Fill the radiator with water and flush the system to get all the coolant out. You can buy a hose connection for your heater hose which will allow you to back flush the system. Most parts stores have the back flush kit.
  4. Dr_Zero

    Dr_Zero Epic Member 5+ Years 500 Posts

  5. Wrench

    Wrench Rockstar

    where i work we actually have a machine that fully cleans out the engine, radiator, and all hoses. It back flushes it and everything. You can try going to a local shop and ask if they have a machine to flush coolant or if they just drain the radiator. If they have a machine id say go for it.
  6. afireinside

    afireinside Member

    Ok is their a petcock on the radiator to drain? or do I have to remove the lower hose???? thanks
  7. eallanboggs

    eallanboggs New Member

    Yes there drain plugs on the block. Two of them. One on Bank1 and another on Bank2. They look like BIG set screws. You need a humongous allen wrench(Hex key) to get them out. The biggest I have it 3/4" and it is just barely large enough to fit(not an exact fit, but it works). I pull these drain plugs when I do head swaps on the LS series V8s. It keeps the coolant from going all over the place when you lift the heads off. Get under the engine with a lite. You'll see them.
    1 person likes this.
  8. TFisher

    TFisher Member

    That is not Dexcool, it's G-05!

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