If you remove the pipe which is lowest on the cooling system
to drain the system, this is normally o.k. Although once you begin to top up the coolant pour the liquid in slowly to prevent any air locks forming. Once full fit the filler cap and run the engine to normal operating temp. Check for leaks and that all visible hoses are warm. Allow the engine to cool, remove the filler cap and top up if needed.
Craig
November 2006