The computed effects of an eccentric rotor on the mass and heat ingress through a gas turbine wheelspace rim seal have been studied using a 3-D Navier-Stokes computer code with a recent three-scale k-∈ turbulence model and orthogonal body-fitted coordinates. All compressibility and thermal/momentum interaction effects were included, as actual engine temperatures, pressures, Reynolds numbers, etc were used. The combined effects of an eccentric coolant inlet seal, in conjunction with an eccentric rim seal, were compared with the case of an eccentirc rim seal alone. It was found that heat and mass ingress into the cavity through the rim seal are not affected by the coolant/purge inlet seal eccentricity, whereas they are strongly affected by the eccentricity of the rim seal. The total heat flux through the rim seal, due to mass ingress thermal transport and turbulent heat diffusion, was examined in order to better understand this wheelspace cavity heating mechanism. It was found that the turbulent heat diffusion flux is a significant percentage of the total heat flux at small rotor eccentricity, whereas it is entirely negligible at large eccentricity.