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Testing oil pressure sender.

in General Tech Discussion 8 years ago
How would I go about testing the Keller oil pressure sender. Right now I am still experiencing oil pressure readings that jump around and are not steady. The oil pressure gauge is an MGL TP-1.

  • Re: Testing oil pressure sender.

    by » 8 years ago

    At 0 PSI you should read 4mA in the current loop, you get a voltage about 0.80V like a straight 200 ohms gauge load. At max PSI 20ma, you get about 4.00V. You could take the sending unit out and connect to air compressor while still electrically connected to gauge or a 200 ohm load with a regulator and gradually increase pressure the 4 to 20 ma current should be linear without jumping around (although engine vibrations can cause the sending unit to fail) consider remote mounting sending unit to isolate vibration damage.
      
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  • Re: Testing oil pressure sender.

    by » 8 years ago

    Hi Clyde,

    To double check and confirm your oil pressure put a mechanical gauge in line and compare the two. There is another plug screw just in front of your sender you can use. This oil pressure swing may also be a bad ground or a bad connection.

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

      
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  • Re: Testing oil pressure sender.

    by » 8 years ago

    Roger,

    I did put the mechanical gauge in and the oil pressure was rock solid no jumping around. I will double check the connections. This is a new engine and all new wiring so the connections should be good. What do you think of testing the sender by removing it and using air pressure?
      
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  • Re: Testing oil pressure sender.

    by » 8 years ago

    Ok, I made a fitting to screw the oil pressure sender into with an air hose connection on the other end. I grounded the fitting to the engine crankcase and applied air pressure in 10 lbs increments up to 70 psi. At each 10 lbs the pressure was steady no erratic movement at all. So I would conclude the oil pressure sender is ok and not faulty. So next would be to use another MGL TP-1 gauge and/or a different oil pressure gauge to see if it is indeed the gauge I have installed. Also, interestingly, the reading was 3 lbs higher than the air pressure at each setting including at zero pressure, which indicates that at 4mA the sender is not sending a zero pressure signal as the Rotax manual says.
    Man I hate electrical problem!!! :angry:
      
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  • Re: Testing oil pressure sender.

    by » 8 years ago

    Still sounds like a poor connection somewhere.

    I hate electrical ghost myself.

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

      
    Report
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