Vacuum Question (Pic inside)

Discussion in 'Fox 5.0 Mustang Tech' started by asecretfile, Aug 1, 2008.

  1. When disconnected from the TB, am I supposed to be drawing a vacuum here? its a fairly strong one at that

    View attachment 309047

    if not what would cause this?

    thanks
     
  2. That is normal, it is a vacuum line from the plenum area. It may be connected to the solenoid valve for the carbon canister. Since I don't have a Cobra upper manifold, I can't say for sure.



    Diagram courtesy of Tmoss & Stang&2birds
    mustangFoxFordVacuumDiagram.jpg

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  3. this is my oil fill nipple to TB hose...so its normal with the engine running that I have vacuum on the oil filler nipple, even though its disconnected from the TB?
     
  4. yeah its normal, its supposed to pull the burned oil into the intake so it doesnt vent to the atmosphere
     
  5. I have vacuum the other way though....oil filler nipple drawing in
     
  6. yes u should have vacume that way its just like a gas can without a hole in it so u need air to be in ur valve pans so oil drains properly
     
  7. Agreed that it's part of the PCV system (it allows bi-directionality in the system).
     
  8. Yes...reconnect it and leave it alone
     
  9. Video

    Well come to find out that intake hissing I was hearing wasnt actually coming from the throttle body, it was from the oil fill neck to TB, that thing has alot of vacuum too. Odd thing is...when I pull this hose loose, my hanging idle problem goes away

    Heres a video

    :shrug:

    gt.flv - Video - Photobucket - Video and Image Hosting
     
  10. That is way too much vacuum from the oil filler port. You may want to check the PCV valve and make sure the filter/strainer element is installed. Also check if vacuum is present at the filler tube port after temporarily removing the PCV valve from its seat.
     
  11. what do you mean by filter/strainer element?
     
  12. #4 below....

    [​IMG]
     
  13. Tried unseating the pcv. With it taken out, the car starts but will not idle with it taken out
     
  14. Replace th PCV valve....... looks like the valve internals are gone (inspect the valve), allowing full manifold vacuum to be applied to the crankcase.
     
  15. I got the car to stay running for a minute with the pcv taken out. When I do that the oil filler still has a little vacuum but much much less. Makes no noise and barely enough to even hold my finger on it

    :shrug:
     
  16. new pcv same thing
     
  17. I can take the PCV out completely, and hold one hand over the PCV hole in lower and the other hand oil fill nipple and when I block off PCV hole, filler nipple pulls vacuum. Block off filler nipple and PCV hole pulls vacuum...pretty strong one. Again this is with manifold vacuum completely taken loose and capped off to test.
     
  18. PCV valve off and vacuum line capped.... and you still have vacuum in the crankcase?
     
  19. yea

    I took off pcv, capped off the line going into the upper...capped off the hole in the lower that it sits in and still have crankcase vacuum

    :shrug:
     
  20. View attachment 308689 ... the only way I think that would be possible is, if there's a vacuum leak in the lower intake gaskets