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Thread: Keeping newly built engine safe

  1. #1
    CarlOrton's Avatar
    Join Date
    Jul 2011
    DFW Area

    Keeping newly built engine safe

    Hi, All;

    I've basically completed assembly of my O-200 for an experimental aircraft. I've been using dessicant plugs in the lower plug mounts and regular plugs in the upper holes. The engine is still on the assembly stand, but will be mounted on the engine mount right around the time of Oshkosh.

    PROBLEM: The dessicant plugs turn pink within a week and a half. Purple after a week, then pink at a week and a half. I then dry out the dessicant and start over.

    The carb mounting boss has been plugged, the exhaust ports have been plugged, the generator mounting hole in the accessory case has been plugged.

    Am I over-worrying this issue? I'm probably at least 6 months away from first flight. I intend to start it for a few seconds once mounted and connected, just to test out the wiring to the EFIS, etc., before I rivet in place the upper panel cover, etc.

    I know the moisture is bad, but I never thought the dessicant plugs would turn color so quickly. I'm in DFW, btw, so it's not like I'm in a coastal area...

    Carl Orton
    Sonex #1170 / Zenith 750 Cruzer

  2. #2

    Join Date
    Aug 2015
    I don't have much experience with dessicant plugs but I've seen them last years in a heated hangar. As long as you keep drying them out and reinstalling them I don't see a problem though. Maybe there's just some moisture in there that is getting dried out and it will get better over time.

    We have a 2l bottle full of dessicant beads hooked up to a fish tank air pump to dry out our engine in between flights and it takes a couple weeks for the stuff to go pink even in the wettest weather.

  3. #3
    cub builder's Avatar
    Join Date
    Nov 2011
    North Central AR
    Did you assemble the engine with liberal amounts of engine assembly lube? Or did you just assemble with a little oil? With lots of assembly lube on the critical components internally, I'd say you are worrying too much. With a little oil used sparingly to assemble the engine, it's probably still fine, but you might want to think about fogging the cylinders to get them a good coating of tacky oil that won't run off. Same for the interior of the engine. A little fogging can go a long ways towards preserving the engine. Fog through the breather tube up front with the dipstick out so the fog will flow through the engine interior and that will fog the area of the cam and cam followers, which is your most likely areas for corrosion. The crank and bearings will hold whatever oil is on them and should be just fine.

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