KatanaPilot
Well Known Member
Our RV-7A has a Titan/ECI IO-360 (originally O-360) with about 300 hours over four years.
During our first condition inspection, cylinders #2 & #4 had low compression - in the mid-50's. I ran the engine several times, rocked the prop and was able to get the compressions in an acceptable (but still low) range. The oil analysis came back good, so we continued to fly the airplane.
The compressions on #2 & 4 came up during the next two inspections, but were still lower than I wanted. Yes, I know, compression readings are not the be all and end all of engine condition.
However, as time went on, we were getting increased oil consumption, the oil was turning black within a few hours and we were getting oil on the belly (and we have a Christen inverted oil system).
I finally decided to bite the bullet and pull the engine. I could have just pulled the two cylinders, but if you read the whole story, you will see why it was fortuitous that I sent then engine in for IRAN. When Penn Yan disassembled the engine, they found this on cylinders #2 & #4.
There was no "smoking gun" as to the cause, but the symptoms I had been having matched the situation they found.
Last week, we reassembled the engine with new bearings, rings (nickel cylinders were ring honed) and new exhaust valves and guides (one valve had the coating delaminating). Ran the engine hard for five hours in the test cell and checked compressions again. All were low and the oil was black.
Good news was we replicated the problem. Bad news was that the cause was not obvious.
The cylinders were measured and were perfectly round (measured cold). Penn Yan thought it might be wise to heat the cylinders up and measure again. They found the smoking gun. The cylinders went 0.010" out of round at the top (where the choke is) - which allowed the rings to expand and oil to get behind them in the piston land.
So the end result is I have four defective ECI/Titan cylinders. These are all post-AD (we checked back in 2017 when we went through the engine) and pre-Continental.
Point of all of this is for any of you with post-AD/pre-CMI Titan cylinders - you may have an issue one day, or if you have these symptoms - this may be the cause.
During our first condition inspection, cylinders #2 & #4 had low compression - in the mid-50's. I ran the engine several times, rocked the prop and was able to get the compressions in an acceptable (but still low) range. The oil analysis came back good, so we continued to fly the airplane.
The compressions on #2 & 4 came up during the next two inspections, but were still lower than I wanted. Yes, I know, compression readings are not the be all and end all of engine condition.
However, as time went on, we were getting increased oil consumption, the oil was turning black within a few hours and we were getting oil on the belly (and we have a Christen inverted oil system).
I finally decided to bite the bullet and pull the engine. I could have just pulled the two cylinders, but if you read the whole story, you will see why it was fortuitous that I sent then engine in for IRAN. When Penn Yan disassembled the engine, they found this on cylinders #2 & #4.
There was no "smoking gun" as to the cause, but the symptoms I had been having matched the situation they found.
Last week, we reassembled the engine with new bearings, rings (nickel cylinders were ring honed) and new exhaust valves and guides (one valve had the coating delaminating). Ran the engine hard for five hours in the test cell and checked compressions again. All were low and the oil was black.
Good news was we replicated the problem. Bad news was that the cause was not obvious.
The cylinders were measured and were perfectly round (measured cold). Penn Yan thought it might be wise to heat the cylinders up and measure again. They found the smoking gun. The cylinders went 0.010" out of round at the top (where the choke is) - which allowed the rings to expand and oil to get behind them in the piston land.
So the end result is I have four defective ECI/Titan cylinders. These are all post-AD (we checked back in 2017 when we went through the engine) and pre-Continental.
Point of all of this is for any of you with post-AD/pre-CMI Titan cylinders - you may have an issue one day, or if you have these symptoms - this may be the cause.