Apex Seal Wear and Failure

Gradual loss of compression, reduced power output, difficulty starting (especially when hot), increased oil consumption, and eventually the engine won't sustain combustion. In catastrophic failure, a broken apex seal fragment can score the rotor housing surface, requiring housing replacement.

The apex seals are the equivalent of piston rings, they maintain the gas-tight seal between the rotor faces and the epitrochoid-shaped housing. Every rotation, the apex seals sweep across the housing surface under spring tension and combustion pressure. Over tens of thousands of rotations, the seal material wears down. The rate of wear depends on lubrication (oil metering pump function and pre-mixing), operating temperature, combustion temperature, and carbon deposit buildup.