The absence of appropriate experimental data is a major factor which is limiting the development of reliable models for heat transfer in Internal Combustion (IC) engine coolant. Following a review of other published work, a cooling gallery simulator has been built to allow not only the nature of transfer to be characterised, but more importantly, to gain representative magnitudes of heat transfer parameters under realistic IC engine operating conditions. This paper highlights the magnitudes of heat flux and heat transfer coefficients that could be expected to be realised in an IC engine throughout the convective and flow boiling regimes. The major known influencing parameters of system pressure, velocity and inlet temperature are presented as well as effects due to surface roughness and vibration. Surface roughness is shown to increase the heat transfer rate except at low velocities, and the effect of vibration on heat transfer is most pronounced at low coolant velocities and pressures.