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Thread: 503 belt tension.

  1. #1

    Join Date
    Jul 2008
    Location
    Pleasant View, TN
    Posts
    30

    Default 503 belt tension.

    My 503 has about 30 hours on it and we are starting a condition inspection. I saw a youtube video that mentions removing some clips to get at the fan belt. Any additional information about how to get access to the belt? Has anybody figured an alternative technique for checking the belt tension? I don't have a tension gauge but might have to get one.

    It has been running great. My brother and I will look it over closely, any suggestions about what else to look for?
    Jeff Dill
    Sold da Fo & bought a Bo
    Kept Dad's Kitfox II/503 flying

  2. #2
    Senior Member t j's Avatar
    Join Date
    Oct 2009
    Location
    Ellensburg, WA
    Posts
    862

    Default Re: 503 belt tension.

    While you have the plastic cover off, cut the mouse ear off it on the bottom right side. Now you can get a finger in there to check the belt tension whenever you want without removing the cover. I check it each preflight. If the belt deflects less than about 1/2 inch when you push it side to side its good.

    The book wording is normal finger pressure, approximately 10 pounds. Deflection must be 8-9 mm.

    I don't pull the cylinders off any more to check the carbon on the pistons and rings. I did the first 50 hr inspection and ended up doing more damage than good. Now each 50 hours I pull the exhaust manifold off and use a wood stick to push on the rings to be sure they move in the piston grooves. I put the exhaust back on and leave well enough alone. Put on new exhaust gaskets if you remove the manifold. If you reuse them they will leak.
    Tom Jones
    Classic 4 builder

  3. #3

    Join Date
    Jun 2009
    Location
    Pittsgrove, Southern New Jersey
    Posts
    113

    Default Re: 503 belt tension.

    In regards to the carbon build up on the 503, I remove one plug from each cylinder. Pump a few squirts of WD-40 on top of the pistons. Wait till the next day then remove the exh. maniflod. Put a pocket retractible pencil magnet into the port to the piston rings. Wiggle the magnet around. If you see the ring move or see a little liquid movement, the ring is 'probable' not all carboned up. Not a substitute by any means for a good decarbon. -Lion8

  4. #4

    Join Date
    Jul 2008
    Location
    Pleasant View, TN
    Posts
    30

    Default Re: 503 belt tension.

    Thanks guys.
    Jeff Dill
    Sold da Fo & bought a Bo
    Kept Dad's Kitfox II/503 flying

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