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Oil Pressure valve

in General Tech Discussion 9 years ago

  • Re: Oil Pressure valve

    by » 9 years ago

    Hi Roger,
    The mushroom was introduced as it has a different radius/contact surface than the ball so it releases the oil pressure at a more gradual rate.
    It is a expensive part compared to the ball.
    The ball works perfectly well 90% of the time and is a well proven, inexpensive part that makes TBO.
    There are some installations that has pressure fluctuations that the mushroom fixes. Why change the whole fleet for a 10% problem?
    In my experience most fluctuation problems, caused by the oil pump, gradually go away by themselves so I assume the ball and seat are wearing in. ( I know this as I never hear back from the people that complain that their new engine has a fluctuation so I can only assume it goes away)
    I would rather go though a break-in period of needle fluctuation rather than spend money and time installing the mushroom. Some people do not agree, so they install the mushroom. Its OK with me.
    Sometimes the oil pressure fluctuation problem is caused by the airframe oil system installation and the mushroom band-aids this. If the oil system has a serious restriction (causing cavitation) or a collapsing hose the mushroom will not help.
    In the end it is more expensive and is not necessary. Just my opinion.
    Rob
      
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  • Re: Oil Pressure valve

    by » 9 years ago

    Hi Rob,

    Thanks for the reply and thought.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: Oil Pressure valve

    by » 9 years ago

    Hi, Rob and Roger,

    Based solely upon what I've read and my limited experience, it seems that the "mushroom" valve includes two features that help prevent pressure fluctuations, namely,

    (1) It has a "stem" which (I believe) helps to prevent the spring from flexing and hitting the side walls, where such contact could (would?) effectively modify the force needed to cause the valve to release; and

    (2) It has a "dimple" at the top which appears to help prevent, or diminish, any type of surface tension (or adhesion) between the top of the mushroom and the portions of the opening that it contacts. If I am correct about this aspect of the mushroom valve, then I wonder whether the specific oil composition or viscosity also plays a part in when the valve (mushroom or ball bearing) releases.

    Like Roger, it is not clear to me why the ball bearing is still being used in new engines, given that there appear to be benefits in minimizing both the likelihood of contact between the spring and the wall, and reduction of "adhesion" forces between the valve and the opening.

    Finally, as I noted in my "Update", I replaced all three components (ball bearing, spring, and bolt), but it is unclear whether it was necessary to do so or whether replacing the ball bearing, alone, and, possibly, the spring, without replacing the bolt would have been adequate.

    Sandy

    UPDATE: Immediately after I posted this I saw that both Roger and Rob had submitted posts (while I was writing this one), although I am not sure that Rob addressed everything in this post.
      
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  • Re: Oil Pressure valve

    by » 9 years ago

    Hi all,
    My oil pressure fluctuations only occur at low revs when the oil is warm, when above idle throttle it's fine, should I be thinking about replacing the ball and spring?
      
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  • Re: Oil Pressure valve

    by » 9 years ago

    Hi Andy,

    Depending on how big the fluctuation it may be normal. If it is only around 5 psi no big deal. If it is 20 psi then the mushroom may help, but a big swing can also be caused by a weak ground to the instrument.

    From a personal standpoint I like the new style oil pressure regulator (mushroom) better, but they both work.
    Just my personal opinion.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report
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