my car runs warm in traffic but below warm on the highway.the guy that i bought it from added some stop leak to the radiator.i flushed the system and replaced the radiator, removed the thermostat and noticed that i couldnt see the water circulating and yes the water pump looks new but it wasnt replaced by me.I have an electric fan but no fan stroud the water pump looks like it has already been replaced.So now im wondering could the water pump be messed up due to the stop leak that was added.