Boost leak and brake booster vacum ejector
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    1. #1
      Junior Member
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      Feb 2019
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      The Netherlands
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      Boost leak and brake booster vacum ejector

      Hello,

      I have a question about the brakebooster vacum ejector.t

      I wanted to see if i have a boost leak and found out that when i pressurize system, air blows trough this valve into the intake tube that is going to the turbo. Other side is going to the brakebooster pump or whatever it is.

      Is this correct? Is this a valve and doest it needs to be closed when on boost? Find it hard to believe its wasting boost by sending it back into the intake before the turbo




      Its next to the intake manifold on the line with the red ring.
      Volvo V50 T5 AWD 2005
      Volvo V70 2.5T 1998
      Mazda MX-5 1.8 Turbo

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    3. #2
      Correct. On boost the valve should shut going out so no air goes to the vacuum pump or goes to the brake reservoir area.
      On Vacuum the valve should be open and pulling air from both areas.
      2006 Volvo S40 AWD T5 M66 - Dusty Rusty
      2012 Subaru Outback 2.5i CVT - Slowmobile - CAI only, Powerstop Rotors+Pads.
      1996 HD Electra Glide - Big Bertha - 10:1 Wisecos; EV13 Cam: Ultima Digital Ignition; Buell Head Conversion; E85 Carb Tuned;

    4. #3
      Junior Member
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      Jul 2014
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      Boston area
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      I'm glad you brought this up since I've been trying to figure out the operation of that valve in the context of doing a brake booster vacuum pump delete. It definitely should not allow air to flow from the intake manifold to the brake booster but its operation relative to the secondary line going to the turbo intake pipe is unclear. Instructions in VIDA for checking the valve indicate you need to clamp the line going to the turbo intake tube and then ensure air can only flow in one direction, toward the intake manifold. What puzzles me is that if the valve is supposed to block all air flow away from the manifold (like with boost) then why is it necessary to clamp the secondary line? Further complicating things, when I test a spare brake booster vacuum hose assembly I have by blowing in the end of that valve I can't seem to get any air to pass through either the main or secondary lines.

      brake vacuum boost line testing.jpg
      2010 XC70 T6 188k; 2006 S40 T5 AWD M66 242k; 2004 XC70 287k; 1998 V70 288k (sold); 1970 Dodge Super Bee 383 Magnum 122k

    5. #4
      Junior Member
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      Aug 2017
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      28
      Quote Originally Posted by kjhiggins View Post
      I'm glad you brought this up since I've been trying to figure out the operation of that valve in the context of doing a brake booster vacuum pump delete. It definitely should not allow air to flow from the intake manifold to the brake booster but its operation relative to the secondary line going to the turbo intake pipe is unclear. Instructions in VIDA for checking the valve indicate you need to clamp the line going to the turbo intake tube and then ensure air can only flow in one direction, toward the intake manifold. What puzzles me is that if the valve is supposed to block all air flow away from the manifold (like with boost) then why is it necessary to clamp the secondary line? Further complicating things, when I test a spare brake booster vacuum hose assembly I have by blowing in the end of that valve I can't seem to get any air to pass through either the main or secondary lines.

      brake vacuum boost line testing.jpg
      I agree this is confusing. Vida by stating that the secondary line going to the overhead pipe needs to be pinched for the flow test, is stating implicitly that there is no check valve between that part of the "Y" and the intake manifold and also implicitly stating that the check valve is only there on the other part of the "Y" ie The "hose going into the pipe to the vaccum pump" from the intake manifold
      This is confusing as this would clearly result in a boost leak according to the vida definition of things.
      From a functional point of view the "Y" valve seems to be acting as a Venturi to create vaccum on the "brake booster vaccum hose" by using the engine vaccum on the intake manifold to pull a constant flow using the part of the "Y" connected to the overhead pipe(which is a feed of filtered atmospheric air)

      if you look at the picture attached below with the red circle, which i suspect is the other check valve for the vaccum pump. To make sure when the venturi is pulling a vaccum it is not pulling a vaccum on the vaccum pump and vice versa when the vaccum pump is pulling a vaccum the check valve on the Y should be stopping air in both the overhead pipe and intake manifold from going into the pump



      let me know what you think about this and what is the symptoms you are expereince @vincentmiata to suspect the hose in the first place ?
      Last edited by Massivesiege; 06-10-2020 at 10:34 AM.

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