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Thread: leak tester

  1. #1
    pokplalya22's Avatar
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    leak tester

    Has anyone used a vacuum pump like this to perform an air leak test? I realize that its negative pressure, but will it give me accurate results? Also, if I'm testing through the pulse lines, is it best to do one at a time, and block off the others, or all at once?


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    improvised tmg97gp's Avatar
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    Yea. Use a A/C vacuum pump.Click image for larger version. 

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    Last edited by tmg97gp; 06-29-2013 at 03:31 AM.

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    Yamaha artisan Cutlass's Avatar
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    You can vacuum test the crankcase as a way to see if its sealed. I'm not sure how much vacuum it should hold because most people around here pressure test their engines in the 5 to 15 psi range.
    That hand pump should work if you want to vacuum test. You may have to pump it quite a bit before it pulls a vacuum but it should work.
    I would recommend you pressure test it since that's what most of us use and are most familiar with. If you start asking us about inHg in vacuum leak specs, we're not gonna have a clue.

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    Happily Self-Employed WFO's Avatar
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    why?

    if you are going to the trouble to test it, then just put pressure in the crankcase rather than vacuum... just get a tire valve and rig it up... its going to be easier to find a leak under pressure rather than vacuum


  6. #6
    Quote Originally Posted by pokplalya22 View Post
    Yes that will work fine on the pulse line,just block the other one off....suction it to 8-10 psi and let it sit for 10 minutes.

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    Yamaha artisan Cutlass's Avatar
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    Quote Originally Posted by DanielDucati View Post
    Quote Originally Posted by pokplalya22 View Post
    Yes that will work fine on the pulse line,just block the other one off....suction it to 8-10 psi and let it sit for 10 minutes.
    Its a vacuum pump, so it reads in inches of mercury. -10 psi is about 20 inHg
    But like WFO said, a pressure test is better because you can spray soapy water on the engine and make bubbles if it is leaking. You can't make bubbles with a vacuum.

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    pokplalya22's Avatar
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    I thought about that.Im thinking about using a smoke tester of some sort.

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    Yamaha artisan Cutlass's Avatar
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    Or just use the standard pressure test everyone else uses. Why go against the grain on this one? Depending on what you have laying around the house, you can pressure test a 2 stroke for pennies or several dollars.

  10. #10
    pokplalya22's Avatar
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    Truth is, I don't have an air compressor, and very limited access to a shop, and pulling the motor is not a feasible option. Btw, I did look for the link about making your own tester, but couldn't find it.
    I already pulled my carbs, and reeds. The reeds are actually in perfect condition. I'm thinking about opening the carbs, and see if maybe one of the diaphragms or something is damaged from the backfire. Not sure if it matters, but I have good amounts of air coming through my pulse lines, tested one at a time. This gives me more hope that maybe it's the carbs.

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