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  1. #1
    Join Date
    Mar 2013
    Location
    Anchorage, Alaska
    Posts
    418

    Default Checking For Vacuum Leak

    Just got back to the car. Currently doing visual check on the hoses. After that, I will do the Carburetor Cleaner method.
    With this method, as not to miss anything, what area or point MUST I spray to test for leak?
    What would be advisable, the spray or the stream with the little red can spray hose?
    Thanks

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  2. #2
    Join Date
    Feb 2010
    Location
    Virginia Beach
    Posts
    3,854

    Default

    You must check all the parts that can leak. All the parts, including mating surfaces, hoses, pipes, and gaskets between the MAF and the intake valves. Include intake pipe, PCV connections, TCV lines, turbo couplings, charge air pipe, throttle pipe, throttle body gasket, intake manifold gasket, injector o-rings.

    Everything subject to vacuum.
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  3. #3
    Join Date
    Dec 2009
    Location
    GA
    Posts
    1,323

    Default

    Quote Originally Posted by Oka View Post
    What would be advisable, the spray or the stream with the little red can spray hose?
    The direct stream with the tiny tube.

    Traditionally, if you used a spray (usually carb cleaner) to detect vacuum leaks, the vacuum leak when sprayed would cause a change in the idle speed. Unfortunately with newer systems (1983+Volvos) the idle speed is so well controlled with the engine control unit you may not be able to notice a change when you spray an area where there is a leak. However if there is a leak in modern systems (96+) you will get a fuel trim code after driving for a while.

  4. #4
    Join Date
    Dec 2019
    Location
    New York
    Posts
    9

    Default

    If you have a torch, propane, acetylene or map gas run that around the vacuum lines and connections(unlit of course) and the idle should pick right up as you approach the leak. Then pin point with carb cleaners small hose.

  5. #5
    Join Date
    Mar 2013
    Location
    Anchorage, Alaska
    Posts
    418

    Default

    Hello folks, Season Greetings to you all!
    Was just getting ready to start the trouble shooting when office priority work came up. Would be back to it, hopefully coming weekend.
    Thank you all.

  6. #6
    Join Date
    Aug 2017
    Location
    Pleasanton CA USA
    Posts
    408

    Default

    Quote Originally Posted by Astro14 View Post
    You must check all the parts that can leak. All the parts, including mating surfaces, hoses, pipes, and gaskets between the MAF and the intake valves. Include intake pipe, PCV connections, TCV lines, turbo couplings, charge air pipe, throttle pipe, throttle body gasket, intake manifold gasket, injector o-rings.

    Everything subject to vacuum.
    Hard to test this way are the far reaches of the vacuum system called EVAP, located in the rear above and behind the fuel tank. A leak here is better pinpointed by doing a pressurized smoke test, sometimes using fluorescent smoke.
    2013 XC70 T6 Flamenco Red (hers)
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  7. #7
    Join Date
    Mar 2013
    Location
    Anchorage, Alaska
    Posts
    418

    Default

    The fluorescent smoke test I see are for the AC system and not for an engine leak. Would you have any link to share?

  8. #8
    Join Date
    Mar 2013
    Location
    Anchorage, Alaska
    Posts
    418

    Default

    Quote Originally Posted by pbierre View Post
    Hard to test this way are the far reaches of the vacuum system called EVAP, located in the rear above and behind the fuel tank. A leak here is better pinpointed by doing a pressurized smoke test, sometimes using fluorescent smoke.
    The fluorescent smoke tests I saw are for the AC system and not for an engine leak. Would you have any link to share?

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