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435C EGT??????

in 912 / 914 Technical Questions 10 years ago
I installed an EGT gauge on cylinder #3 on my 912ULS. The probe is 95mm for the exhaust flange. Full power climb out at 5,500RPM shows 435C. 5,000RPM cruise shows 425C.
should I question the gauge?



Thanks
20150318_160326.jpg (You do not have access to download this file.)

  • Re: 435C EGT??????

    by » 10 years ago

    Could be a faulty probe. I had one reading cold like that.
    Swap it with one of the others and you will quickly know what is going on...
      
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  • Re: 435C EGT??????

    by » 10 years ago

    Only have a single EGT reading gauge and probe. Further tests ARE leading to a faulty probe.
      
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  • Re: 435C EGT??????

    by » 10 years ago

    Hi Dave,

    That is cold. Does the EGT temp swing around a lot? Has this cold temp always been like this or just since you applied the header wrap cloth? The wrap look pretty new. If it has been just since then then move the header wrap cloth away from the probe and do not let it get around it.

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

      
    Report

  • Re: 435C EGT??????

    by » 10 years ago

    Roger,
    Thank You for the reply. This is a new install EGT probe on one cylinder only (#3). I have no history on actual EGT on any cylinder before this install. The instrument shows a steady reading, no bouncing of needle at all. The header wrap is simply replacing the wrap that was on before installing the probe. I did some "bench" testing yesterday on the probe and instrument. It seems the probe is not producing the correct millivolts at any temperature. When it is heated to a dull red it only shows 17mv which represents @425C. A different probe was setup on the bench and the readings in mv and temperature were quite normal. I'm 90% sure it is a bad probe as rec'd from my vendor.

    I'm curious as to your comment on the header wrap. You mention moving it away from the probe. Can you elaborate as to why?

    Again Thank You for your help!




    20150321_151513.jpg (You do not have access to download this file.)
    20150321_130413.jpg (You do not have access to download this file.)
      
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  • Re: 435C EGT??????

    by » 10 years ago

    Hi Dave,

    Glad you found your problem. I always keep an extra probe or sender of some type around when a suspected bad one comes to the shop. It's just a quick and easy swap at times to either rule in our out the probe or sender itself.

    The header wrap comment dates back about 6 years for me. I have EGT probes on #3 & #4 cyl. I wrapped them years ago a went to fly. The probes were normal before the wrap and after the wrap they were bouncing all over the map about a 150 degree fast swing, but mainly on the high side. The wrap at that time was under the probe and it was pushed through into the exhaust pipe. Called Dynon and Rotax and no one had a clue. I pulled the warp out from under the probe so it had full metal contact, but let it wrap around the base. Went to fly with the same results. Then I moved the wrap about 1/4" away from the sides of the probe and all went back to normal. Everyone suspects something in the wrap material played havoc with the probe's electrical output. Over the years I have now seen this same phenomena several times and each time when the wrap is pulled back slightly every thing goes back to normal.

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

      
    Report
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