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emission tubes on exhaust

Discussion in 'Tech Discussion' started by Howard Rogers, Jan 6, 2019.

  1. Howard Rogers

    Howard Rogers Junior Member

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    Truck Year:
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    I hope my question is in the correct place. i recently purchased a 86 gmc 2500 4x4 from a gentlemen that had it in his cellar after painting it 20 years ago. needs some assembling but its a nice truck for what i need.. my question is i removed the smog pumps to get to replace the fuel pump. I'm not going to reinstall them. can i leave the tubes in the manifold and block the exhaust off where they come uo to meet the rubber hose. i hate the thought of messing with exhaust if i don't have to... thank you
     
  2. rpcraft

    rpcraft Full Access Member

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    I have seen some guys cut and fold the ends but you want to make sure and seal them well. Not sure what the tubing is but if it is steel I would make sure they are welded or otherwise it is an exhaust leak waiting to happen. Cuationary info though, in some states if they see the tubes on then there is a chance that they will require it be emissions compliant.
     
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  3. Charlie

    Charlie Full Access Member

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    :welcome:
     
  4. Howard Rogers

    Howard Rogers Junior Member

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    as the tubes come up from the manifold they taper together and become one tube going a little above the valve cover.they end as a threaded nipple ( i believe ).. there is a piece that is coupled at that point witch accepts the hose that i believe goes to the belt driven pump. I'm wondering if i can disconnect it at that point and put a cap on it of some kind. almost looks like a JIC hydraulic fitting but it is not. Thank you for the welcoming
     
  5. Craig 85

    Craig 85 Full Access Member

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    I'm assuming you're referring to this valve by the dip stick. It is a one way valve that only lets air go to the exhaust manifold.

    I have done it several ways over the years. Before emissions testing, we used to remove the tubes and just put bolts in the exhaust manifolds to block them. My K30 came this way from the PO. Later, when we started testing every 2 years, I would remove the smog pump and tie the two hoses together with a metal sleeve right where is says Made in the USA on the heater hose.

    IMG_1405 (2).jpg
     
  6. Howard Rogers

    Howard Rogers Junior Member

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    you are correct. mine seems to come up past the valve cover more and is a bigger unit than the one your showing .i thought i could buy threaded cap for both of them. i don't mind tying them together with one hose if thats what you meant.. this is a nice truck but will get very little use. the exhaust is tite and sometimes when you start poking around you open a can of worms. i will start it and put my hand over it.. if it doesn't leak i will tie them together with one hose thank you very much for your reply
     
  7. Craig 85

    Craig 85 Full Access Member

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    Your truck probably had the dual smog pump set up which started after 1/1/85. My truck, although an '85, was built in 11/84 and still qualified under the old emissions laws. You may also have the factory stainless exhaust manifolds which were only used until the 1987 model year when EFI came out. I don't think they make replacement air tubes for this style of manifold, so if you remove them be careful. I was lucky they make replacements in my style as the treads were shot on one of the air tubes causing an exhaust leak.

    [​IMG]
     
  8. Howard Rogers

    Howard Rogers Junior Member

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    I'm going to leave them for now and try to plug them up top. I'm not worried about inspection my state don't do emissions on a 86.. + i work ant a place that does inspections.. thanks to all for your time to answer
     
  9. Rusty Nail

    Rusty Nail Build the wall - deport them all! Supporting Member

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    I would put it back like it was meant to be and not mess with it.
     

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