Abstract: A simple, reliable bypass valve construction (50) is provided for use in conjunction with a donut oil cooler (16) having an aluminum multi-piece housing (28). The bypass valve construction (50) is easily accessible and readily replaceable so as to lend itself to serviceability. The invention is incorporated in an oil cooler (16) having a housing (28) with a coolant inlet and outlet (42) and (44), and a surface (26) adapted to be sealed against an oil filter (14). The oil cooler (16) includes a plurality of interconnected heat exchange units (21) located inside the housing (28), with an oil inlet to one of the units and an oil outlet from another of the units. An oil bypass is provided through at least some of the interconnected heat exchange units (21) and communicates with a bypass outlet (62) in the housing surface (26).

Abstract: In order to eliminate components and fixtures, facilitate assembly, avoid leaks, and reduce cost in a heat exchanger for exchanging heat between two fluids such as a coolant and oil, the heat exchanger includes a header plate having a central opening defined by a column integrally formed with the header plate together with a radial opening. A plurality of heat exchange units are stacked on the header plate. The heat exchange units each comprise a pair of plates joined together at inner and outer peripheral edges to thereby sealingly define a plurality of first chambers for the flow of one of the fluids wherein a column-receiving opening is provided radially inwardly of the first chambers thereof.