The car's water pump is an important part of car. The water pump continuously supplies coolant to vehicle's engine, preventing engine from overheating. A leaking or failed bearing can cause serious engine damage. If coolant is leaking from under vehicle or temperature reading is too high, your vehicle's water pump may need to be replaced.
1. Park your car overnight and have your garage floor clean concrete. If you can't park your car in a garage with a clean concrete floor, place a piece of light-colored cardboard right under engine underneath car. Note that water pump is more susceptible to leaks while engine is running, so it is not recommended to check for leaks while engine is running.
2. Check cardboard next morning. If coolant drips from cardboard, then there is a leak somewhere, most likely in water pump. Other places where coolant leaks are radiator hoses, heater hoses, antifreeze plugs, gaskets, or radiator itself. To narrow it down, place cardboard directly under water pump. If you find a green liquid on cardboard, it is antifreeze. This suggests that there is a coolant leak somewhere.
3 Check water pump pulley. Check round part that belt wraps around front of water pump. Rock pulley back and forth and if it gets loose pulley needs to be replaced because bearings are about to fail.
4 Listen to sound of machine. Open hood and start engine. If you hear a low friction noise, water pump bearing may be broken. If it's already broken, sound is obvious. Similar bearings are found in A/C compressor, power steering pump and alternator, so be sure to hear where sound is coming from as it is usually hard to hear if engine is running.
5 Check for leaks around water pump. If you see water dripping or leaking out, then there is a leak. Many water pumps have outlets ahead of seals, and if seals are broken, water will leak out of outlets.
6 Notice if temperature indicator is on. If vehicle does not circulate enough coolant due to a leak or failure of water pump, engine temperature will rise and warning light will come on.
7 Check if coolant light is on. If it is lit, there may be a leak in coolant reservoir or a faulty water pump. Another possibility is a leak in cooling system.