Vacuum or boost bleed off noise when crawling in 1st gear

Discussion in '2007+ Mustang GT500 Tech' started by CJ-, May 29, 2018.

  1. CJ-

    CJ- forum member

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    is it normal to hear a boost or vacuum bleed off sound as I’m moving the gt500 around the driveway? I’ll hear this swooshing sound while crawling forward in 1st gear and while reversing.
     
  2. CJ-

    CJ- forum member

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    I’m almost certain the vacuum bleeding sound is coming from a clutch booster cause I hear the vacuum bleed/leak as I’m pressing or releasing the clutch pedal. And while I’m at a stop, I’ll have to pump the clutch pedal 3 times until I stop hearing the hiss of vacuum through the clutch pedal.
     
  3. 01yellerCobra

    01yellerCobra forum member

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    AFAIK there is no vacuum hooked up to the clutch master cylinder. If it's really hissing from around the clutch pedal I'd start looking for fluid leaks.
     
  4. redfirepearlgt

    redfirepearlgt forum member

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    ^^^ The clutch pedal displaces fluid from the res. to the slave cylinder to disengage the clutch. In fact you can buy res. that will separate the clutch system from the braking system and there is no vacuum mods to be made. I agree with the good man from SD, that you may wish to look for potential leaks around the clutch pedal actuator if there is a problem at all. It just may be something you only recently noticed. Happens to me all the time. I drive most of the time with windows down, air off, and radio on. It's when I have radio off, AC on and windows up I start hearing things I thought were never there before. Sometimes it's just me, sometimes its due to recent mods, sometimes it;s actually an issue.
     
  5. CJ-

    CJ- forum member

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    I’ll try to post a video so you can hear what I’m talking about. It’s sorta difficult to discribe but the hissing is loud and can be heard clearly through both windows.

    Does the supercharger have some sort of vacuum controlled bov or pressure relief valve?
     
  6. 01yellerCobra

    01yellerCobra forum member

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    Yes it does. It should be on the side of the blower. But the clutch won't affect that at all.

    What clutch is in the car? I have a Mcleod twin disc and there's a hissing sound right when it's starting to catch. It's normal for these clutches.
     
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  7. travelers

    travelers Senior Member

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    Yes
    You got that answer out before I could.
     
  8. 01yellerCobra

    01yellerCobra forum member

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    Lol. It was either answer the question or do some work. We see which one won.
     
  9. RocketcarX

    RocketcarX 95% of my weight is fuel

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    The brake booster would make this noise from the same basic area. Chances are you are on the brakes and the clutch at the same time so it would seem like a clutch noise when in reality the brake booster is leaking vacuum when you press the brake pedal. Its something to check anyhow.
     
  10. travelers

    travelers Senior Member

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    A way to test the vacuum system is put a vacuum gauge in the system and press on the brake peddle and see if you continue to loose vacuum. You will see some loss when you push on the peddle at first but should build back up as you hold the peddle at one position. If not you have a booster leak.
     
    RocketcarX likes this.
  11. RocketcarX

    RocketcarX 95% of my weight is fuel

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    You could also just unhook the vacuum line to the booster, plug the line and move the car a few feet and see if the noise is gone.
     
  12. CJ-

    CJ- forum member

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    Turns out, it’s my 2 piece Macleod clutch.


    However, one more question before this thread is killed... on deceleration in 1st and 2nd gear between 2k-3k rpms, is it normal to sometimes hear a faint goose honk sound?

    Sounds like Hooooonnnnnnnkkk lol