A crossflow heat exchanger includes an outer housing, an inlet that receives a hot fluid to be cooled and a monolithic manifold includes a central receiving reservoir and one or more outer reservoirs. The fluid received at the inlet passing into the central receiving reservoir. The exchanger also includes an outlet connected to the one or more outer reservoirs and tubes disposed within the outer housing that connect the central receiving reservoir and the one or more outer reservoirs. The monolithic manifold includes a gap formed between the central receiving reservoir and one or more outer reservoirs.