Spark plug boot with ventable seal

摘要

An improved sealing boot for a spark plug assembly is provided which includes a sealing and venting feature capable of preventing pressurized contaminants from reaching the spark plug by effectively sealing the spark plug mounting bore while permitting pressurized gas accumulating in the plug well to be vented to the engine overhead. The sealing and venting feature includes at least one annular sealing rib formed on the outer surface of the boot. The radial length and width of the sealing rib, and the resiliency of the material forming the rib, are selected to cause the rib to deflected outwardly an optimal degree, when the assembly is positioned in the bore, and to engage the bore wall with a sealing force so as to permit the desired sealing and venting. The optimal deflection causes the creation of an additional sealing force due to the pressure of fluid against the deflected portion of the rib thereby ensuring sealing.