RE: UMS Evolution Radial Care and Operation
Todays discussion refers to the danger of hydraulic lock on these radials. Due to the design of radials oil can seep down and pool into the bottom cylinders. Because liquids are basically non-compressible, if the engine is not checked first, the use of an electric starter or a strong arm can damage a connecting rod to the flooded cylinder. When getting ready to start the engine for the first time for the day, slowly turn the prop by hand. If you encounter a point where the compression is felt to be much higher, STOP!!!!!!! Drain that cylinder by removing the glow plug thus allowing the oil (or fuel) to leave. Over priming can also cause this condition. Next topic will cover valve adjustment -Tom