Abstract: An intake manifold for a multicylinder internal combustion engine includes intake runners for conducting air or air and fuel to intake ports formed in the engine cylinder head and an EGR passage formed in the manifold and extending generally parallel to the crankshaft of the engine. Secondary EGR passages extend from the EGR supply passage to intake runners or intake ports, and a coolant passage formed in the manifold extends generally parallel to the EGR supply passage and has a common wall with the EGR passage.

Abstract: A borescope sealing apparatus and plug includes semi-spherical sealing surfaces on the plug's sealing end and a conical hole sealing seat to receive the sealing end. The invention provides good sealing during engine operation wherein thermal growth causes misalignment of the borescope holes. The borescope plug further includes an axial shaft and a spring loaded end having a spring means which is operable to bias the sealing end into the sealing seat. The spring means suggested are crest to crest wave spring, coiled spring, and a pressurized bellows. The sealing apparatus and borescope plug is particularly useful for sealing borescope holes in double wall casings such as those found in gas turbine engines.