How can you tell if your car's water pump needs to be replaced?

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.

Steps

How can you tell if your car's water pump needs 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.

Tips

If you find a puddle of water under car on a hot day, it does not mean that problem is in water pump or cooling system. When air conditioning system is running, condensation will form in vehicle. Leakage of condensate from under car is absolutely normal.

Look for small holes, also known as lacrimal openings. If water pump breaks or fails, drain hole will leak.

Sometimes there may be no leakage or bearing noise and everything, i.e. fans, belts, hoses, thermostats, radiators, heater cores, covers, etc., works fine. Aside from steam escaping from lid when overheated, this is normal in most cases, as lid is designed to relieve excess pressure and is a fail-safe device to protect other components.

Some water pumps use plastic impellers to push coolant, and some coolants corrode after additive depletion (coolant should be changed every three to seven years to prevent engine damage when additives deplete). The water pump impeller wears out and will not be able to push coolant, so car will overheat. Remove radiator cap and perform a cold start to see if this is case. You should see fluid moving in radiator. If you can't see it, it's likely that internal water pump vanes are gone or only a small portion remains. However, if there is a thermostat in car, such a check is meaningless, since coolant will only circulate if thermostat is open at operating temperature, and you certainly do not want to open radiator cap at operating temperature.

Warning

If coolant level is low and vehicle starts or has just started, allow vehicle to cool before adding water or coolant. If engine temperature is high, adding cold water will cause a sudden change in temperature, which will damage cylinder block and turn initial low cost into a high cost.

Do not fill car with 100% coolant, this will cause car to overheat or overheat. Add according to car's recommended amount, usually 50/50 and some 70/30. Never use pure water, boiling point of water is too low for modern engines.

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