RogerH
Member
On my flights to & from OSH 2023 and home SLC, UT my IO-360 was using progressively more oil, eventually almost the Lycoming max limit of 1 qt per two hours Subsequent compression tests were good but borescope inspection on the left (pilot) side cylinders #'s 2 & 4 showed significantly less cross-hatching. This was producing some blow-by evidenced by oil residue on the exhaust valve stem and left underside of the aircraft. Those two cylinders are now removed and heading to Western Skyways for rework with the expectation oil consumption should return to the roughly 8-10 hours per quart after break-in I was experiencing previously.
What has me baffled is the right side cylinders #'s 1 & 3 have good cross-hatching, no sign of oil loss, and look to be good to remain on the engine. Since all four cylinders are operated in the same manner in flight I'm curious if others have seen lopsided wear on horizontally-opposed cylinders -- is this normal, ABnormal or ???
Background: The previous owner had all new Lycoming cylinders installed during a major overhaul by Poplar Grove in 2016. He subsequently put about 100 hours on the engine and I've since put another 200 on. Not a lot of hours but winter weather permitting regular flights. All Blackstone oil analysis reports have been good, no red flags, not making any metal.. Regular oil changes with CamGuard since I bought the plane (typically annual or every 30 hours ish) with normal CHT & EGT readings (380F/1350F typically in cruise).
Anyone have any similar experience or good theories of the cause?
Thanks
What has me baffled is the right side cylinders #'s 1 & 3 have good cross-hatching, no sign of oil loss, and look to be good to remain on the engine. Since all four cylinders are operated in the same manner in flight I'm curious if others have seen lopsided wear on horizontally-opposed cylinders -- is this normal, ABnormal or ???
Background: The previous owner had all new Lycoming cylinders installed during a major overhaul by Poplar Grove in 2016. He subsequently put about 100 hours on the engine and I've since put another 200 on. Not a lot of hours but winter weather permitting regular flights. All Blackstone oil analysis reports have been good, no red flags, not making any metal.. Regular oil changes with CamGuard since I bought the plane (typically annual or every 30 hours ish) with normal CHT & EGT readings (380F/1350F typically in cruise).
Anyone have any similar experience or good theories of the cause?
Thanks