2. Warm up the engine to normal operating temperature and, without turning it off, squeeze the upper radiator hose with your hand. If, when you release the hose, you clearly feel a push of liquid in it, then the water pump is functioning properly.
Caution! Try not to touch the fan impeller with your hands!
3. The water pump is equipped with an inspection/vent hole. If the seal fails, coolant will start to leak from the hole. Have a flashlight and a small mirror handy - the hole is located at the bottom of the pump body, directly under the assembly axis. The presence of brownish deposits around the hole indicates a faulty seal - slight discoloration of the surface (light gray ring) should not cause concern.
4. If the pump shaft bearings fail, a howling sound may be heard at the front of the engine while it is running. This should not be confused with the whistling sound made by the drive belt when it is released. Bearing wear can be detected by the presence of play when rocking the hub/pump shaft (remember to turn off the engine and remove the belt from the pulley first).
5. Even in the absence of external signs of wear, a final conclusion about the condition of the water pump can only be made after removing it and examining it in more detail.