Nanofluids are fluids containing engineered colloidal suspensions of nanoparticles in ordinary base fluids, that are of interest for cooling systems because of their enhanced transport properties, especially thermal ones, as compared to those of the base fluids. However, the interactions (i.e., erosion, corrosion and possible nanoparticle deposition) of such nanofluids with metallic materials are largely unknown. The authors have designed, built and instrumented an erosion-test instrument for nanofluids, which allows accelerated testing of the effects of a nanofluid jet on metal targets. Exploratory work is presented on the wear and erosion effects on copper and aluminum targets when impacted with suspensions of alumina and of silicon oxide nanoparticles in coolant fluids (i.e., for weight concentrations of up to 2% nanopowders in distilled water and in solutions of ethylene glycol in water). The observed erosion and corrosion effects, and material surface changes are discussed as baseline for further investigation.