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Ron's Web Site
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Date: 7-26-2014
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Number of Hours: 2.00
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Manual Reference:
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Brief Description: Intake Tube Leak
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Since I installed the engine, #2 cylinder has always read low EGT/CHT at idle. Around 1300 RPM, the temps would then rise to about the same as the other cylinders. Also, the engine was fairly "poppy" at idle. Finally, I've never been able to get an RPM rise with idle cut-off, which indicates that the engine was lean at idle. I replaced plugs & plug wires, dialed back the timing slightly, borescoped the cylinder, did the valve wobble test, and always had good compressions. I initially attributed the poppiness to deposits from running mogas, however, the borescope didn't substantiate that. After talking via email with the editors of Light Plane Maintenance regarding the possibility of an induction air leak, I pulled the intake tube and lo and behold the connector was rattling around, definitely giving rise to a possibility of an air leak. I then contacted my local Lycoming distributor, as Lycoming is supposed to have a Tool Rental Program, where special tools such as the swager needed to tighten up the connector, are supposed to be available for a "nominal fee". Well, it turns out their idea of nominal is a deposit of roughly $7,000 dollars and a one month rental of about $700. I related these events to Bob Barrows, and to his credit, he mailed me at no cost his homemade swager, which worked extremely well. I added Loctite 510 to help seal it as well. After one flight, the EGT/CHT's are equal to the other cylinders, and the poppiness is greatly reduced, and idle is smoother, as well. The mixture is still to lean, as I don't get a RPM rise with idle cut-off, but I'll try adjusting it some more.
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Loose intake tube connector - note sag
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Swaging connector
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Swaged and sealed connector
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