The water pump is an essential part of your engine.  Coolant is circulated throughout the engine block, heads, and radiator by your Daihatsu water pump.  If your water pump breaks, it will not be able to circulate the coolant, the coolant will boil, and you will break down.  There are three main reasons for water pump failure.  The first, most common reason is leaking shaft seals.  You can detect a leaking shaft seal by locating a coolant stain around your vent area.  The second common reason for water pump failure is noisy shaft bearings.  Regular wear in the bearing and normal oxidation of the lubricant on your bearings will cause them to fail.  Supporting an off-balanced fan can also result in damaged bearings.  A slipping impeller on the water pump shaft is the third most likely reason for water pump failure.  To avoid these problems, you should replace your water pump every 100,000 to 150,000 miles.