Tango Mike
Well Known Member
YIO-360-M1B factory new installed by builder (not me) in June 2012. When I bought the airplane in September 2013, it had mineral oil for the break-in period, and I switched to Phillips X-C 20W50 at about 40 hours. Oil consumption had stabilized, cool cylinders, operation normal, as it has been since I bought the airplane, with no significant differences in cylinder parameters as viewed on the G3X engine monitoring system. The engine now has about 70 hours.
Today for my first annual, with the assistance of an experienced A&P, we found the following compression numbers on a cold engine:#1 78/80, #2 45/80, #3 78/80, #4 76/80.
With air hooked up and the #2 cylinder under pressure, we can hear air escaping from the oil filler tube. When we checked that same cylinder with a spark plug installed and rotated the prop through a compression stroke, we can hear air in the filler tube as well, but in comparison with that same test on one of the other cylinders, it didn't sound that much different. Ran out of time today or we would have repeated the compression test on a warm engine.
I'm going to call Lycoming in the morning to discuss this with them, but the A&P suggested that the #2 cylinder might not be fully broken in yet.
I'm curious if anyone has run into something similar and has suggestions about troubleshooting.
Thanks in advance for any help.
Tosh
Today for my first annual, with the assistance of an experienced A&P, we found the following compression numbers on a cold engine:#1 78/80, #2 45/80, #3 78/80, #4 76/80.
With air hooked up and the #2 cylinder under pressure, we can hear air escaping from the oil filler tube. When we checked that same cylinder with a spark plug installed and rotated the prop through a compression stroke, we can hear air in the filler tube as well, but in comparison with that same test on one of the other cylinders, it didn't sound that much different. Ran out of time today or we would have repeated the compression test on a warm engine.
I'm going to call Lycoming in the morning to discuss this with them, but the A&P suggested that the #2 cylinder might not be fully broken in yet.
I'm curious if anyone has run into something similar and has suggestions about troubleshooting.
Thanks in advance for any help.
Tosh