I recently started my 29th Condition Inspection on my RV-4 and found interesting images while bore scoping cylinder # 3. These radial lines are present all around except for the lower quarter where normal crosshatching is found. They stop short of top of piston travel.
Oil consumption is 1 quart in 7 or 8 hours and compression is mid 70s except for number 3 which is 66/80. I’m suspecting a broken oil control ring, but there has been no change in oil consumption and the combustion chamber isn’t particularly oily. The parallel O-360 A1A has only 172 hours SMOH on new cylinders. I hesitate to pull a cylinder if not necessary. Has anyone seen this condition before and is it something to be concerned about? Any insight is appreciated. I apologize for image quality. They are iPhone pictures of my borescope screen.
Oil consumption is 1 quart in 7 or 8 hours and compression is mid 70s except for number 3 which is 66/80. I’m suspecting a broken oil control ring, but there has been no change in oil consumption and the combustion chamber isn’t particularly oily. The parallel O-360 A1A has only 172 hours SMOH on new cylinders. I hesitate to pull a cylinder if not necessary. Has anyone seen this condition before and is it something to be concerned about? Any insight is appreciated. I apologize for image quality. They are iPhone pictures of my borescope screen.