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Question about oil pressure and when it bypasses

in 912 / 914 Technical Questions 6 years ago

  • Re: Question about oil pressure and when it bypasses

    by » 6 years ago

    ...Can I open the 2 purple wires and hold a voltmeter to see if it fluctuates?...


    Ref. >>> UMA Gauge colors...
    2x Violet = Internal Gauge Lighting.
    White = Signal from Pressure Sender
    Red= 12v Power
    Black = Ground

    The Violet wires are for the backlighting of the gauge.
    The gauge itself is going to be on the White and Black wires.
    A resistance check is only going to be good to tell you if the meter is blown.
    The meter is working so the actual value is not significant.
    If the meter has an internal voltage regulator that is going bad; That would fit the symptoms.
    Temporarily replacing the meter would be a valid test.

    If you were holding 2000rpm steady in the video and the pressure was varying from 38 to 48 psi it is unlikely to be a stuck needle on the gauge causing it to move.

    The problem seems to be erratic.
    It is still not clear if this is a real fluctuation or just a display problem.
    I would reattach the Mechanical gauge and the Electrical sender at the same time through a Tee fitting.
    Until you can demonstrate both gauges moving in unison or one moving independently of the other, we are still just guessing.

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.

      
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  • Re: Question about oil pressure and when it bypasses

    by » 6 years ago

    "If you were holding 2000rpm steady in the video and the pressure was varying from 38 to 48 psi it is unlikely to be a stuck needle on the gauge causing it to move."

    Vibration from engine/airframe could be affecting connection internally/externally in gauge/meter intermittently thereby causing the needle to jump erratically.
      
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  • Re: Question about oil pressure and when it bypasses

    by » 6 years ago

    I'm leaning on the sender or I would replace the oil pressure ball bearing (and spring) with the mushroom style. That has tons of people smooth out oil pressure and even raise it 5 psi.

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

      
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  • Re: Question about oil pressure and when it bypasses

    by » 6 years ago

    Bill,
    I was thinking to try to install the mechanical pressure guage in the hole in front of the sender hole. I think it's for a turbo?

    Garret,
    I will trace the black and white wires from the guage and jumper the connections out, the ground is already done. Should only be one more.

    Roger,
    I just replaced the sender with a 2 prong remote sender. Think that sender could be bad?
    And the ball, doesn't that only regulate the high pressure? If the issue is pressure dropping to low on takeoff, that ball would never move correct?

    Thx all!
      
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  • Re: Question about oil pressure and when it bypasses

    by » 6 years ago

    Bill,
    I was thinking to try to install the mechanical pressure gauge in the hole in front of the sender hole. I think it's for a turbo? ...


    The port on the face of the Oil Pump is a Pressurized Oil Supply Port commonly used to supply Oil to a Turbo or a Prop Governor.

    FYI, while this port appears on the Oil Pump it is actually far removed from it functionally.
    The Oil leaves the Pump on the Left side of the engine near the Oil Filter.
    It travels down the Left Crankcase Half to the rear of the engine then crosses over to the Right Crankcase Half and then flows forward to where it appears on the Right side of the Oil Pump.
    Functionally, this Oil travels about three feet getting from the Oil Pump To the Oil Sender.
    Whatever pressure you see on the sender, you can be assured that all parts of the engine are seeing the same or slightly better pressure.

    What is strange is that your pressure varies slowly over the course of 5 to 10 seconds.
    Most people with Oil pressure variations normally see it flutter rapidly more times in one second than you can count. This video is an example of the typical problem

    https://www.youtube.com/watch?v=e-oo_tASCRU

    If it turns out to be an Oil Pressure Regulator problem, I have a proprietary fix for that.

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.

      
    Report
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