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heads

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by K5Dan, Dec 13, 2002.

  1. K5Dan

    K5Dan 1/2 ton status

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    was having engine trouble /forums/images/graemlins/mad.gif.when i took pushrods out ,and pushed on valves none moved except for 7 cylinder intake moved real easy . this is not supposed to happen is it ? going to take heads off .do you think it could of damaged anything else? /forums/images/graemlins/confused.gif
     
  2. heavy4x4

    heavy4x4 1/2 ton status

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    If you're just pushing on the top of the valves, yes they should move...provided the following two conditions. 1) if you push harder than the valve spring compression rate 2) if the piston isn't at the top of it's stroke, thus not allowing the valve to go past the combustion chamber (should still move a little anyway).
    To try and figure out why seven's intake moved easily...I'd have to say the spring is weak/broken. (It's not easy to manually depress a valve spring)
    Did you wreck anything...no.
     
  3. K5Dan

    K5Dan 1/2 ton status

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    thanks i'll have it off tommorow . just hope i didnt damage anything like piston .
     
  4. heavy4x4

    heavy4x4 1/2 ton status

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    Describe the engine problems you were having...I could possibly figure out what's wrong, and if not me, I'm sure others would have suggestions.
     
  5. K5Dan

    K5Dan 1/2 ton status

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    idleing funny hesitation black smoke fuel coming from tail pipe tapping sound oh the engine is a 87 350 tbi probably will help also check engine light came on then went back off
     
  6. heavy4x4

    heavy4x4 1/2 ton status

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    Could you locate the tapping in the engine? Is it by the #7 valve/cylinder?
    Also, are you sure it's fuel coming from tailpipe and not just condesation? I'd be surprised if unburnt fuel made it all the way out the cat, muffler, and exhaust tubing.
     
  7. K5Dan

    K5Dan 1/2 ton status

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    yeah, what you said !think maybe the intake valve is stuck or not working right could that be the problem ?i am not very savvy on this.
     
  8. heavy4x4

    heavy4x4 1/2 ton status

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    Hmmmm, not too sure. Maybe someone else will ring in. But here's my thinking out-loud: if it were a busted/weak return spring on the intake of cylinder #7, you might get some backfiring through the intake/tbi. If the piston were blown/connecting rod busted...you'd know for sure. The tapping noise - ??? I'm still thinking on that one.
    If the intake valve itself were completely stuck in the closed position (rocker pivoted all the way up), you'd have a major problem because that would mean a lifter or cam lobe would be mushroomed, or a pushrod would be bent. (Ok, just realized it isn't stuck closed, because you said you could push that down easily). And if it were stuck open...you'd definitely get backfiring through the intake, and that wouldn't make that valve any easier to depress.

    Well, my brain is spent...I don't have any more suggestions. It may just take some disassembly, and then you'll figure it out.
    Someone else ring in if you see something I blantantly overlooked.
     
  9. fortcollinsram

    fortcollinsram 1/2 ton status

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    What code did you computer shoot out...if you dont have a code scanner, simply ground the diagnostic terminal on the ALDL hookup...looking at the ALDL hookup (mine is under my light swith under the dash) there are 2 (2 pins tall)horizontal rows and it is about 6 or 7 pins wide. on the top row, simply run the paper clip from the furthest right hole to the one just to the left of that...
    so if the letter below represet the ALDL hookup as you see it from the front, run the paper clip from etof

    abcdef
    ghijkl

    Then turn on the ignition (don't start the engine)and count the blinks and pauses. The first code will be 12, the will be one blink followed by a pause followed by another 2 bllinks. This pattern will repeat 3 times and then go to the next code. 12 is the only code, the computer hasn't stored any codes...

    Good luck

    Chris
     
  10. unsane

    unsane Guest

    trashed hydraulic lifter?
     

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