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Exhaust Valve???

Discussion in 'Chevy Trucks' started by owen, Sep 6, 2003.

  1. owen

    owen Member
    from florida
    Messages: 34

    It all started when I noticed a new rattle after changing the starter. It sounds like an exhaust leak where the donut goes.

    The rattle is about at 3k when I accelerate and seems to come from the starter area. The starter seems fine. So did everything else upon inspection. The weird thing is - it does not rattle in neutral, but if I put it in drive and hold the brake it rattles around 3k.

    The exhaust on this truck is fairly new, so I figured it may have loosened up. I went to tighten the bolts holding the exhaust pipe to the manifold and of course snapped one off up inside the manifold.

    I noticed a valve on the passenger side manifold at the exit end. It is hooked to rusty vacuum motor. WTF is that? I am familiar with exhaust valve technology, but I didn't think it was around in 1985.

    My plan is to pull the exhaust, weld a new bolt (stud) into the exhaust manifold, cut that valve out and weld up the hole in the side of the manifold from the actuating arm.

    Any input before I do this?
  2. wyldman

    wyldman Member
    Messages: 3,265

    That is a heat riser valve.The vacuum motor pulls it closed when cold.

    You can't remove it,or the y-pipe will not fit.You can take it out and remove the butterfly.It must go back in place so the exhaust will fit properly.

    Don't try welding the manifolds or the valve.It's all cast iron,and cannot be welded without special equipment\procedures.
  3. owen

    owen Member
    from florida
    Messages: 34

    Oh.. guess I'll be going to the muffler man. There is nothing special about my AC buzz box, although my welding skills could qualify for the Special Olympics;)

    My fear is that the heat riser valve is stuck in the "cold" position and resrticting exhaust. The muffler man should be able to cut out the butterfly easily enough. I just don't think that is a necissary peice of gear, especially in Florida.