David Lloyd Posted November 19, 2020 Report Share Posted November 19, 2020 Was #4 the new cylinder? With compression on that cylinder good, the oil control ring may be broken. That much oil in that short of time, most likely something is broken. Scope all the cylinders for any other damage before having just one repaired. 2 Quote Link to comment Share on other sites More sharing options...
PT20J Posted November 19, 2020 Report Share Posted November 19, 2020 I wouldn’t operate the engine until further investigation. I had a oil control ring break and it took out the cylinder and piston skirt which ran metal through the engine including contaminating the connecting rod big end bearing. It had been getting about 2 hrs per quart since I bought it. Filter, borescope, compressions and recent oil analysis were good at prebuy. I flew it about 25 hrs and it was running well. We discovered the damage at annual when the #4 compression had dropped to 56/80. At this point, we found metal in the filter and part of the ring in the suction screen. We didn’t investigate further than pulling the cylinder since we discovered that the cam was also spalled. I replaced it with a factory rebuilt A3B6 and had the prop resealed and the oil cooler overhauled due to the metal contamination. The point is that if a stuck ring breaks, it can do a lot of damage. Skip 2 Quote Link to comment Share on other sites More sharing options...
jetdriven Posted November 19, 2020 Report Share Posted November 19, 2020 thats good advice Quote Link to comment Share on other sites More sharing options...
Guest Posted November 19, 2020 Report Share Posted November 19, 2020 Either a broken ring, or one that was installed backwards. Clarence Quote Link to comment Share on other sites More sharing options...
carusoam Posted November 19, 2020 Report Share Posted November 19, 2020 Well... That gets it narrowed down quite a bit..! Dental camera down the spark plug hole may tell a bit more... But it sounds like that cylinder is getting pulled already... Good compression indicates the cylinder surface may be in good condition with good compression rings... But, the oil control ring sounds like it is no longer doing its job... Timing is important, metal bits circulating in the engine is bad... no need to fly it... PP summary only... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
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