1. Welcome to PlowSite. Notice a fresh look and new features? It’s now easier to share photos and videos, find popular topics fast, and enjoy expanded user profiles. If you have any questions, click HELP at the top or bottom of any page, or send an email to help@plowsite.com. We welcome your feedback.

    Dismiss Notice

Missing Vacuum Lines

Discussion in 'Chevy Trucks' started by owen, Aug 31, 2003.

  1. owen

    owen Member
    from florida
    Messages: 34

    1985 C20, 454

    This truck seems to have been stripped of all vacuum lines. I noticed plastic things which should have vacuum lines attached but don't. They are:

    1) On the intake manifold next to where the water bypass hose connects from the water pump.

    2) On top of the cover for the thermostat.

    3) On an electrical, 2-wire switch bolted to one of the bolts holding the t-stat cover on.

    4) On the side of the air filter. There are most likely more I havn't discovered yet.

    My Haynes manual has no vacuum line diagram and has prooved pretty much useless in other areas too. Are these lines important and necessary? What manual will show how they should be routed?
  2. wyldman

    wyldman Member
    Messages: 3,265

    While all of the OEM lines aren't neccesary,you should have at least the basic stuff hooked up properly.Vacuum advance,EGR,heat riser,etc,should all be connected.

    Do you have a vacuum decal under the hood somewhere ? It will tell you where a lot of stuff goes. If not,make a list of everything you have,and I'll see if I can explain how to hook it all up.
  3. owen

    owen Member
    from florida
    Messages: 34

    Here are three switches. There is also one with 3 openings on the side of the air cleaner.

    The one with the wires on it did not change when I turned on & off the AC. The hot wire stayed hot the whole time. I would imagine the other two are heat switches.

  4. wyldman

    wyldman Member
    Messages: 3,265

    The electrical vacuum switch is usually used to bleed vacuum off to a certain component,like dist advance,or EGR.

    The other two are TVS'S,or temperature vacuum switches.They are used to control vacuum to certain devices when the engine is cold.
  5. razz

    razz Junior Member
    Messages: 9

    85 C-20 454

    Hope this helps...Chilton's"General Motors Full-size Trucks 1980-1987 repair manual#[8577]28622,page 4-90, shows a vacuum routing diagram for a 1986 454, 4BBL. Sorry I dont have any way to electronically send you a copy. Best of luck,