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  • Oil pressure indication

    I'm ready to start my engine for the first time. Today I put fuel in the tanks and did a flow test and then did what I could to prime the oil system and with spark plugs out, spun the prop by hand a bunch of times and then motored the starter. The idea was to motor the starter until I see pressure on the oil pressure gauge. That's when I noticed the problem: On my G3X, the oil pressure shows 104-105 psi. Whether the starter is cranking or not, it shows 104 or 105 psi. Of course I don't know the brand of the oil press sensor off hand, all the sensors came with the panel setup I got from an avionics shop so it should all work well together. Has anyone encountered anything similar with a digital setup like this? The other gauges seem to show proper static indications. There is no way I'm starting a new engine without being able to monitor oil pressure.
    Rollie VanDorn
    Findlay, OH
    Patrol Quick Build

  • #2
    Try the avionics provider's forum, they will know the answer. If they don't have a forum, try the Dynon forum or similar.

    By the way, Lycoming's splash lucubration system only works properly at RPMs at idle or higher. Pre-oiling is probably a lower wear & tear approach to getting oil onto parts before starting, compared to cranking the starter with the ignition disconnected. Hot oiling is also a good idea.
    Last edited by Battson; 11-08-2017, 08:14 PM.

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    • #3
      I have had minor problems with my Garmin system. Go to Garmin.com, go to the aviation support page and get their phone number. Call them, they are very helpful and supportive. They will probably be able to give you an answer in minutes.

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      • #4
        Mr Rollie,
        My sensors came in the Garmin sensor package. Since yours came from a shop, I'd guess yours did too. Tomorrow, I'll check which unit is configured for my oil pressure sensor. I'll let you know.
        Have you configured the other sensors? If not, there's still a chance that some other parameters won't indicate correctly. Don't mean to alarm you, just don't want you to be shocked if something gets really strange...

        Bill

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        • #5
          Something you may want to check... the fuel pressure and oil pressure sensors look very similar and could be easily interchanged.
          Larry Driver
          Bearhawk 4-Place Quickbuild N22LD
          Mogollon Airpark, Overgaard AZ

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          • #6
            Are you running a restrictor in the line to the sensor? If so, maybe the tiny hole is blocked?

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            • #7
              My oil pressure sender/sensor is a Kavlico P10455-150G
              Larry spoke of similar senders. I don't have a fuel pressure sender, but my MAP sender is a Kavlico P4055-30A. I have to put my readers on to see the different part numbers of the two identical units.
              Hope this helps!

              Bill

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              • #8
                The manifold pressure sensor, fuel pressure sensor and oil pressure sensor are all Kavlico and all look the same, with just a small difference in the part number, They all start with P4055- the oil pressure is -150, the MP is -30 and the fuel press is -50. I spent a good portion of the day trouble shooting this. They are all installed in the right places, I didn't do restrictors, maybe I will add them though, The G3X configuration is set for the correct sensors, and they are getting 5Vdc. After 3 calls to Garmin support, they are out of ideas other than checking continuity which doesn't really make sense to me. They have voltage and when I disconnect any of the three wires, the indication on the G3X goes to a red X. To me that shows continuity.

                Also its all three sensors that are not right. The oil press shows 105 psi, the manifold press shows 43 inches and the fuel press shows 35 psi. I've called the avionics shop that built the harness but they haven't returned my call yet.

                I asked the Garmin guy if the wires could just be hooked up wrong at the sensor but he didn't think that would cause this problem. Tomorrow I'll probably start swapping wires around to check anyway. I mean its only 3 wires per sensor, so not that many possible combinations

                On the up side I did address a few other little issues such as a small fuel leak that developed overnight. Not too shocking as I just added fuel for the first time yesterday. Turned out one of the flares on a line going into the fuel selector had either a burr or a crack in the flare. managed to cut off the end and put a new flare on and no more leak.
                Rollie VanDorn
                Findlay, OH
                Patrol Quick Build

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                • 22LD
                  22LD commented
                  Editing a comment
                  Please keep us posted, Rollie. I'm in the process of running my harnesses made by an avionics shop for my G3X system. Now I'm thinking I should maybe recheck all of the pin-outs. No easy undertaking. At a minimum I do plan to test to make sure all of the "hot" leads are pinned correctly before powering the system.

              • #9
                I'd disconnect the "high"lead first, one sender at a time, to confirm that the wires are on the right senders. Then, I'd disconnect the "low" leads, one at a time. I found some "low" leads mis labeled in my harness - FROM AN AVIONICS SHOP. The fact that some 'low leads' were swapped caused me major heartburn.
                Good luck!

                Bill

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                • #10
                  With all the readings being high, sounds like possibly the voltage being applied to sensors may be off - bad common, internal voltage regulation, etc.

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                  • #11
                    Got it! I got the wiring schematic from Garmin's installation manual and pulled the big connector from the GEA-24 and checked continuity on the wires to the sensor. The avionics shop had miss labeled/ mixed up the ground wire and the sensor output wire. Same deal on all three pressure sensors. Switched the wires around and it all works as advertised. The engine fired right up and everything seems to be right. Time to start getting ready to have the FAA come look at the plane.
                    Rollie VanDorn
                    Findlay, OH
                    Patrol Quick Build

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                    • #12
                      CONGRATULATIONS!!
                      Nobody likes to have problems, but isn't it a good feeling to figure it out and solve the issue!
                      You do know that we want pictures..

                      Bill

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                      • #13
                        I had a similar problem. I had to take two miss labeled wires out of a plug and swap them around. In my case the Garmin tech told me that it sounded like two wires were wrong. He told me which pins to check. Glad you were able to solve the problem

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