"A mod has attempted to assign BlockID 4064 to the Fluid 'ic2coolant' but this Fluid has already been linked to BlockID 4039. Configure your mods to prevent this from happening."
This is not a IC2 Bug. That is a 4096 BlockIDs mod bug which got implemented into forge. So it is a minecraftforge bug. You just need to adjust the config file and then there is no trouble.
