A heat exchanger assembly includes a first member defining fluid passages therein for a first heat exchanger fluid. A second member defines fluid passages therein for a second heat exchanger fluid. The second member is engaged to the second member with an interference fit. A method of assembling a heat exchanger includes thermally resizing at least one of a first heat exchanger member and a second heat exchanger member and assembling the second heat exchanger member to the first heat exchanger member. The method includes thermally equalizing the first and second heat exchanger members to engage the second heat exchanger member to the first heat exchanger member with an interference fit.