Avidflyer2
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- Mar 25, 2016
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Today's compression check on the Arrow's IO-360-B1E (180 HP) Engine showed a decided sudden loss of compression in the #3 Cylinder. The differential compression tester reading was 38/80 with leakage into the exhaust system. I had noticed a bit of an exhaust leak at the exhaust pipe gasket at the cylinder, so I decided to pull the exhaust pipe to inspect the exhaust port area of the cylinder before doing anything else. The exhaust port wall is cracked from the valve seat vertically along the port wall but did not penetrate thru to the exterior cooling fins. The crack is readily visible with the unaided eye and instantly relegated that cylinder to the scrap heap. After removing the cylinder one can see that there is a crack between the two valve seats and that the valve seats have loosened up a bit around one quarter of their perimeter. I believe the crack is allowing the air to leak around the valve seat and into the exhaust port, not between the valve and the valve seat. A quick records search shows that this cylinder is on at least its second run and having accumulated over 3,000 hours TIS in the last 18 1/2 years. (I found the OH tag from 1999 having the same cylinder serial number & work order number)
