water bypass vacuum check valve

Discussion in 'General Ranchero Help' started by RAGNAR, Feb 22, 2019.

  1. RAGNAR

    RAGNAR In Second Gear

    Messages:
    36
    Location:
    California
    I can't find any info on the check valve that is hooked to the vacuum lines at the firewall, All I really know is that I do not have one and my heater/a/c switches are not working like they should be. Does anyone have info on the check valve and the proper routing of the vacuum lines that go to it? Mine is a 1979 500 351M Thank you for any help
     
  2. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
    8,244
    Location:
    Everett, WA
    Yeah, I posted it somewhere on site here. But, all you do is go to a parts store, and look in the Doorman parts...it'll be there.
     
  3. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
    8,244
    Location:
    Everett, WA
    IIRC, this is what Babe's check valve looks like:

    Screenshot_20190223-120407.png
     
  4. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
    8,244
    Location:
    Everett, WA
    If I think of it, I'll see if I can snap a pic underhood, but don't hold your breath, I'm having phone troubles
     
  5. RAGNAR

    RAGNAR In Second Gear

    Messages:
    36
    Location:
    California
    I really need to know which line go to it, My vacuum canister has 2 lines coming off of it going to the vacuum block on the firewall(almost the exact same spot) I do not feel like that is correct. I have yet to find a vacuum diagram that shows that check valve and where the lines that it connects to go,
     
  6. Hillbilly

    Hillbilly In Maximum Overdrive

    Messages:
    5,268
    Location:
    Winchester, TN.
    If you have two lines on that tomato can, the check valve is built into the can. The larger line goes to your vacume source while the other smaller line goes to the heater controls. The check valve in the can often fails but the cure is to put another check valve in the line from the can to the source ( intake or vacume tree ) That canister is a necessity, it makes the trap door motors stay where you put them on long up hill grades when there is little engine vacume. All vacume controls leak slightly as they age so keep a canister to store reserve vacume.
     
  7. RAGNAR

    RAGNAR In Second Gear

    Messages:
    36
    Location:
    California
    okay awesome thanks you for the info. I guess mine is hooked up just fine then. Just need to finish routing vacuum lines better
     
  8. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
    8,244
    Location:
    Everett, WA
    I think I have an incorrect or busted can then, as the vacuum doesn't change while driving up hills or accelerating. Gonna have to check that out.
     
  9. Hillbilly

    Hillbilly In Maximum Overdrive

    Messages:
    5,268
    Location:
    Winchester, TN.
    Andy, those cans have a paper gasket between the can itself and the cast check valve. Often that gasket get's broken by the act of pulling the rubber hoses off the nipples. A quick and dirty fix is a bead of rtv surrounding the valve where it meets the tin can. Block one nipple and use a Mighty Vac on the other nipple to check if it holds vacume. If both nipples are the same size try reversing the source line to see if it has a functioning check valve. The hole in the center is usually for the vacume source.
     
  10. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
    8,244
    Location:
    Everett, WA
    Thank you. I'll give those a look when I install the heater hoses. Another reason why these forums are such a boon: having access to people who know because there's no printed info available.
     

Share This Page