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Thread: Electrical Advice

  1. #1

    Question Electrical Advice

    I have an electrical mystery (to me) and no skill at all in things electrical. I have a Westach dual instrument for oil pressure and temp. Yes I know they are not the best..... For some time the temp would drop to zero for a bit then jump back to temp. Did this for a several months. Then one day I found if I turned off and on the strobes it would read again instantly. Now it seems to stay reading. So.....
    The other day I had the strobes off and when turned on I see the temp dips a tiny bit in time with the strobes. Strobes off and nav lights on - the temp drops about 20 degrees and stays there until nav lights off then full temp again.
    Any ideas on what I can check or do to troubleshoot further? It's not that big a deal but isn't right and I'd sure like to correct it.
    Thank you!

  2. #2
    CarlOrton's Avatar
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    Not saying I know the answer, but a bit more information could help.

    Homebuilt or spamcan? Engine? Separate alternator or one integral with the accessory case like an AeroVee? Internal or external voltage regulator? Are you sure that your alternator (regardless of homebuilt or not) has enough capacity with everything else running? As in, if you're running a 10A alternator, lights in general pull a big drop in voltage. Your Westach may be sensing severe voltage drop.

    Does this happen at all engine speeds or only at idle?

    Carl Orton
    Sonex #1170
    http://mykitlog.com/corton

  3. #3
    Quote Originally Posted by CarlOrton View Post
    Not saying I know the answer, but a bit more information could help.
    Gladly Carl!

    Homebuilt or spamcan? Homebuilt

    Engine? O-320-E2A

    Separate alternator
    external voltage regulator

    Are you sure that your alternator (regardless of homebuilt or not) has enough capacity with everything else running? Yes

    Does this happen at all engine speeds or only at idle? I'll check but what I have been observing is at cruise.

    Thank you!

  4. #4

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    Sounds like a bad/corroded ground to me. A bad ground can make lots of things do goofy stuff.

    Marshall Alexander

  5. #5
    Richard Warner's Avatar
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    I agree about the ground. That's the first thing that came to my mind.

  6. #6

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    where is ground fastened?

    If all these items are using the same ground terminal this sort of feedback can happen. Try running a seperate ground wire to the engine block for your gauge.

  7. #7
    Thanks all. Will check ground this weekend.
    Thanks again!

  8. #8

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    Quote Originally Posted by gyrojohn View Post
    If all these items are using the same ground terminal this sort of feedback can happen. Try running a seperate ground wire to the engine block for your gauge.

    Exactly, when everythig is stacked up on top of each other, this is a good place to "trap" moisture, thereby starting corrosion.

    Marshall Alexander

  9. #9

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    yes but

    Even with brand new aircraft there can be problems with stacking grounds. By brand new I am meaning at the factory.
    Lights and such don't mind having common grounds but some sensors that use voltage differences need a separate ground all the way to the engine.

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