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Smoke from intake tube?

Discussion in '1992-Present Chevy & GMC models' started by Blaze, Dec 23, 2002.

  1. Blaze

    Blaze 1/2 ton status

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    When I drive my 92 Yukon for any distance, then stop and turn it off, smoke comes out of the intake pipe. I'll shut the motor off, open the hood, and pull off the tube that leads to the air cleaner and smoke comes out. It isn't billowing out, but there is a fair amount of it. I replaced the PCV valve and cleared the breather tubes, but that didn't help. Does anybody have any ideas? I'm perplexed. /forums/images/graemlins/confused.gif
     
  2. Shorts

    Shorts 1/2 ton status

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    are you talking about that little heat riser tube that connects to the top of the manifold? if so, check the inside of the tube for any kind of waxy/oily residue. on the element housing, just inside the hole where the tube connects, there's this little cylinder-shaped thingy. i've been told that that "thingy" contains some kinda wax/oil. after the truck heats up, warm air goes up the tube and heats the wax...i can't remember what the exact purpose of the wax is though /forums/images/graemlins/grin.gif ...BUT, my point is(finally) that your little wax thingy might be leaking stuff down the tube and its getting burnt when it gets down to the hot manifold.
     
  3. Blaze

    Blaze 1/2 ton status

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    Nope, I'm talking about the big plastic tube that draws in fresh air. I'm thinking that some oil is leaking out of the valve cover right above that preheater hose and burning off on the manifold, then the smoke is traveling up that preheater hose and coming out the other tube. Sound like that might be happening?
     
  4. Highjaxx

    Highjaxx 1/2 ton status

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    I've had my dad's '96 3/4 5.7 Vortec blows smoke from under the hood on start up sometimes. It doesn't start, and makes a backfire kind of noise. Then you turn it over again and runs strong. Weird. /forums/images/graemlins/blush.gif
     
  5. Blaze

    Blaze 1/2 ton status

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    Well, I fixed it. The PCV valve was clogged, creating a ton of pressure in the valve cover and causing the oil to leak down onto the manifold and then the smoke came up the preheater hose and out the intake tube. What an odd chain of events. /forums/images/graemlins/rotfl.gif
     
  6. 89K1500Chevy

    89K1500Chevy 1/2 ton status

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    I got a vacume leak from the MAP senosr line from the TBI and its causing it to run werid and had somke coming out the Preheater hose and tail pipes. so check your vacume lines its hard to tell if they arent on a vacume tester. Also put new EGR valve on. /forums/images/graemlins/truck.gif /forums/images/graemlins/usaflag.gif www.zombieoffroading.8m.net
     

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