Over the years we would have some engines that produced oil leaks or cracked coolers more than other engines. Some of the senior mechanics blamed the cracks on the hydraulic lifters. We would pull all the lifters out and clean them or change them. The engines would finish their time without oil coolers leak but, that usually only meant the last 500 hours or less. The other thing we have done is balance the prop/engine with a chadwick by someone who know what they were doing.
For the most part, we came to believe that an engine shaking/vibrating from propeller balance or valve timing issue caused the cracking. If nothing else the engine usually finishes it's life with less oil seepage or leaks after the above recommendations.
One other thing that 'WILL' help your engine life is turning the Max. takeoff RPM down to 2800 or less. Many commercial operators wanted every bit of power they could pull from the engine but, the engine would have a lot more cylinder, cooler, case half, intake system, exhaust system and accessory problems. Propeller tips breaking the speed of sound is not only noisy but also vibrates the engine and airframe with 300 horsepower of force. Continental knew about this problem many decades ago so they developed the replacement IO-550 with a takeoff RPM of 2700 or less.
Klaus Marx - Piper Pacer Pilot
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