Sundowner 23
Flight Crew Instrument; Flight Crew Private
Flight Crew Last 90 Days 40; Flight Crew Total 350; Flight Crew Type 35
Troubleshooting
Aircraft Equipment Problem Critical
Flight Crew Returned To Departure Airport
Aircraft
Flied IFR from ZZZ to ZZZ1; engine began to make a strange noise on initial climb. Noise began to get more noticeable and then I noticed a vibration beginning. I canceled IFR and returned to my home field of ZZZ. When the Mechanic removed the cowling to investigate he discovered the number 3 cylinder of my Lycoming O-360 had sheared off all 4 of its deck studs and 2 of the 4 through bolts had nuts backed off their posts. The engine was overhauled in 2013 at [FBO] and had 200 hours since overhaul.
Beechcraft C23 pilot reported a loss of engine power on climb out resulting in return to airport.