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Plastic cylinder head covers are an important component in modern engines. Their design is governed not just by space, economy and functionality considerations, but also by the growing number of functions that have to be accomplished by the cover, such as: provide a leak proof seal to the cylinder head and timing belts, isolate the vibrations transmitted from the engine through the cover to the environment, control the crankcase pressure and house the device(s) to separate oil from the blow-by gas. Additionally, the use of plastic affords the development of lighter, more elaborate and cost effective solutions. The present work describes analytical and experimental efforts aimed at understanding and, thus, improving the air/oil separation (AOS) in a given type of cylinder head covers.

Accelerated testing techniques for cylinder head gaskets have become absolutely necessary because of developments at engine manufacturers including: shorter engine development times, high costs of vehicle and dynamometer testing, new material generations for engine components, and new engine generations and longer engine life This paper will describe two accelerated test methods for Multi-Layer Steel (MLS) cylinder head gaskets and will discuss the most important parameters which influence MLS cylinder head gasket functional performance. We will describe how these parameters have been duplicated in the laboratory using the accelerated tests: the Bending Simulator and the Hydraulic Pulsator. The test method results have been confirmed based on detailed metallurgical analysis of MLS gaskets; comparing field (dynamometer and vehicle) tested gaskets to those gaskets evaluated on accelerated tests.