Front Seal Tool


How many of you have replaced the front crankshaft seal on a Lycoming engine? Yeah….I see a lot of hands up, which is what I figured. These seals can last the life of an engine, or be problematic children that seal and leak and get replaced a bunch of times in a short number of hours. My hypothesis is that it all has to do with how clean you get the bore. Or what adhesive you use. Or how you hold your tongue when you apply the sealant. Or… well, you get the point – probably a lot of things.

One of those is what tools you use. Removing the old seal means finding the right combination of picks and other implements of destruction. They have to be small enough to fit behind the prop shaft, but big enough not to bend when you stab them in to the seal. Oh – and don’t scratch the crankcase bore!

Installing the new seal also needs the right tools, and I recently found what I think it perfect. Trying to push it carefully in to place without damaging it, I started looking for a tire iron – but they are all too large. Except… the “irons” I carry in my bicycle tools! Made of nylon, small, smooth, not damaging to rubber – the perfect thing to grab. And the best thing is – it worked! They usually cost a couple of bucks each, or a set of three for five dollars or so, and are often right on the counter of your local bike shop. Definitely something to add to your tool box.

We’ll have a feature article in Kitplanes on the entire process of replacing a front seal sometime in the future.

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Paul Dye
Paul Dye, KITPLANES® Editor at Large, retired as a Lead Flight Director for NASA’s Human Space Flight program, with 40 years of aerospace experience on everything from Cubs to the Space Shuttle. An avid homebuilder, he began flying and working on airplanes as a teen and has experience with a wide range of construction techniques and materials. He flies an RV-8 and SubSonex jet that he built, an RV-3 that he built with his pilot wife, as well as a Dream Tundra and an electric Xenos motorglider they completed. Currently, they are building an F1 Rocket. A commercially licensed pilot, he has logged over 6000 hours in many different types of aircraft and is an A&P, FAA DAR, EAA Tech Counselor and Flight Advisor; he was formerly a member of the Homebuilder’s Council. He consults and collaborates in aerospace operations and flight-testing projects across the country.


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