Any failure of the water pump may cause severe damage to the engine through overheating and incase the pump seal breaks, the coolant will spill out in front of the engine. Four-cylinder engines also have weep or vent holes that can be inspected with a flashlight; some light black discolouration around the weep hole is normal but any brown discolouration or actual coolant means the water pump needs replacement. Also, when running, a howling noise can be heard at the front of the engine when the water pump shaft bearings are defective and when the engine is not running and the drivebelt is removed, the shaft can be felt rocking up and down indicating wear, unlike in the case of the drivebelt which results in a squealing noise. In V6 engines, the timing belt drives the water pump which is concealed behind the timing belt cover; a failed pump seal will spurt out coolant on the instrument cluster and on the thermostat housing a coolant temperature sending unit is attached. Should there be an overheating signal, verify the level of the coolant and make sure that all the connectors in the wiring harness between the sending unit and instrument cluster are in good shape and firmly tightened. In models since 1999, the air intake duct can be removed to reach the sending unit. Disconnect the electrical connector of the sending unit, and with a 12-volt test light attached to a good ground, probe the electrical connector on the harness side an assistant switches the ignition key to the On position, but does not crank the engine. Providing a properly functioning gauge, the test light will light up and the gauge needle will deflect, indicating a faulty sending unit in case of none. When the test light is on and the gauge needle does not move, the gauge is defective and when neither the test light nor the needle moves, the problem is in the wiring harness. An ohmmeter can also be used to check the sending unit by unplugging the electrical connector and measuring the resistance, with a hot engine the resistance is about 104 ohms, with a variation of plus or minus 14 ohms and the resistance decreases as the engine temperature rises and increases as the engine temperature falls. In case the sensor does not pass these tests, it is necessary to replace it. To change the sending unit, be ready to prepare the new unit by applying thread sealant to the thread, empty the radiator cap to get the remaining pressure in the cooling system, and finally install the radiator cap. In models since 1999, once more, to get to the air intake duct, unscrew the old sending unit out of the thermostat housing and install the new one within a few minutes to limit the loss of coolant, making sure that it fits firmly. Install the air intake duct (when it was taken out and then reinstate it).check the engine coolant (filling it up as needed) to bring it to the desired level.he bottom of the cover, which can be verified by removing the cover and examining the pump with a flashlight and a mirror.