Questioni have 1998 hyundai xl 3 door hatch in australia it has a problem with the water it keeps boiling i replaced the thermostat but it does not stop it from getting hot is this telling me that it is the water pump or is there a different problem
AnswerIf your coolant level is proper, it's doubtful you have a water pump problem. I've heard of cases where the impeller rusted away or broke off, but I've never seen one. Since you've already replaced the thermostat, you might start by checking the fuses for the radiator and condensor fans. They're located in the underhood fuse box.
If the fuses are okay, do a cooling system audit. First check your coolant level. If your coolant is low, check for and repair any leaks.
If the coolant level is okay, remove the radiator cap and start the engine. You're looking for the coolant to start to circulate. This should occur when the engine reaches operating temperature and the thermostat opens. If the coolant does not begin to circulate, you either have a blockage in the system, or you have a problem with the water pump impeller as described above. The coolant should begin to circulate prior to the coolant boiling out of the radiator (although normal expansion will force some out). If you're unable to see the circulation through the filler neck, monitor the temperature of the radiator hoses. If only one hose is hot, the coolant is not flowing. If both hoses are hot, the coolant is flowing.
Once the coolant starts flowing, the fan should eventually begin cycling on and off to keep the coolant at the proper temperature. Once again, this should occur prior to the coolant boiling out of the radiator. If the fan turns on and blows only cool air off the radiator, you have insufficient flow and need to return to the blockage scenarios. If the fan doesn't start, you'll need to investigate the fan control circuit. Presuming the fuses are okay, the next most common problems are with the fan motors themselves and burned terminals in the connectors.
