Another excellent and highly educational video, thanks Mike!

Thank you - I could never have learned that much from a book and you held my attention for the entire time.

Heating and cooling for interference fits is a waste. Heating charges one part with energy and it is not necessary to complete an interference fit. On the GE90 high pressure turbine, both stages are joined with no bolts and nuts, but by interference and bayonets. We used to heat one part and cool the other until we realized all we were doing was reducing the worktime of the join. After that, we cooled one part with liquid nitrogen and left the other stage at ambient room temp. We found we had a much longer worktime, ensuring a proper connection without having to rush the work.

Need to remake these videos in HD would be so much better. But great info.

Thanks for the great discussion on this matter.

I learned more today...fantastic presentation! A must see!

Thanks great info!!!!

Thank you

Have you ever come across a thermal fatigue failure of an intake valve - i.e. a crescent shaped piece breaking off the edge of the intake valve -much like the exhaust valve failures? Had personal experience of this happening on intake valves in 2 separate cylinders of an O-235- L2C - over 10 years ago.

MAN, if that slide at 16:40 doesn't tell you that bringing a cold engine up to temperature GENTLY and slowly is a good idea, NOTHING WILL. The extension of those rings out of that piston when everything is cold borders on SCARY. Would be EVEN worse in VERY cold temperatures, like 30 below, where there is ANOTHER 100 F added. As an engineer that slide gives me the willies. The discussing of shedding exhaust valve heat is interesting, as well. Good talk. This particular presenters almost always are.

2 minutes, I thought you were going to say 2 seconds. What the pilot do get out his checklist?

podrías subirlo en mejor calidad. saludos

19:20 is a leak down test, not a compression test

Stuck valve= Marvel Misery Oil in the oil. 1/2 Qt. every oil change. Great Job mike !!!!

I had stuck exhaust valve, piston struck and punctured. I put aircraft down in a field. weeks before there seemed some roughness to the engine. Never ignore anything out of the ordinary.

On piston expansion, are the manufacturers using alloys that don't expand very much or is it because the operating temperature fluctuation is hugecompared to automotive use.

"Always keep CHT below 400°F"?!?! My 0-360 hits 400°F+ on nearly every Summer departure. It would be impossible to get any sort of climb rate if I throttled it back enough to keep the temps below 400°F. #3 regularly hits 430°F by the time I'm 3000ft AGL, no matter how rich the mixture. Even at 1300°F EGT cruise, my mean CHT is typically 380°F. This is on a JPI EDM 700. Now I"m scared...

Isn't this really a 'leak' test versus a 'compression' test?

This is a leak down test, not a compression test, they are very different test. And give different information. Also the tools used are different.

Those engine makers are a lot of hot heads.

The 80 PSI is NOT for historical reasons. The leakdown tester has a metered air hole to the cylinder side pressure gauge that demands a specific pressure to give the correct value. I expect if all flow paths gave equal flow differences for equal pressure drops it wouldn't matter, but they don't. I expect you could conceivably design the leakdown tester for a different pressure (not an aero engineer, electrical), but a specific pressure would still be required for each design. He makes an excellent point about testing when the cylinder geometry is junk by virtue of its coolness. Another MAJOR contributor to noise in compression test readings is the amount of oil on the cylinder wall at the time, dry to wet is MANY percent. In fact it is THE TEST for worn rings in a car engine, add oil if the compression is crap, and if it goes up to near good, it's rings, not valves that are your primary problem. And it's a GOOD test.

So a pilot shouldn't take the girlfriend and the kids up even after you work on his plane? Having said that. I wouldn't take passengers up, after I worked on my plane.

Thank you