May 15, 2025

"Continentals burn valves and Lycomings stick valves"

1 hour 11 minutes

Valves are sticking all over as the hosts give advice on how to avoid pulling cylinders.

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Full notes below:

Rick has a 182 with a new Pponk engine and he’s burning lots of exhaust valves. He’s wondering what he should change operationally. Paul said to borescope more frequently to find the asymmetric burn patterns before

they need to be replaced, and if they start to have asymmetric patterns to lap them immediately. He recommends borescoping every 100 hours. Mike gives some initial results of Savvy Aviation’s borescope initiative, which after 100,000 images found that 7 or 8 percent of valves showed signs of heat distress. Twenty five percent of the engines had at least one valve that was heat distressed. About 85 percent of those valves were in the early stage of distress and could be lapped. Only about 15 percent were considered late stage.

Brad has an SR22 with an IO-550 that had high oil usage. They pulled a cylinder, rehoned it and put on new rings. Later he started asking questions about torquing the through bolts, and the shop told him they held a wrench on the other side, but didn’t torque both sides. He’s wondering if he should go back and retorque the bolts. Mike and Paul think he’s probably ok.

Bruce is sick of sniffing gas fumes. They installed new fuel senders and a digital fuel gauge in their 172. They followed the procedure to calibrate the fuel senders, but he’s having trouble getting it correct. He’s as much as two gallons off from what it should be. Paul starts by asking what bucket Bruce is using because the utility buckets from the home stores are unreliable as calibrated containers, he said. The other issue is the wet wing construction, which can lead to dams that make it difficult to fully defuel or refuel. Bruce has even accounted for temperature. He’s within half a gallon on one side, which Paul said is usually as close as you can get it.

Ed is stirring the pot. He read that in an article in the American Bonanza Society publication that operating lean of peak is bad for engines. Obviously the hosts disagree, and a discussion of the merits of rich of peak and lean of peak ensues.

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