How to Tell if a Car's Water Pump Needs Replacement

Co-authored by Rocco Lovetere

Last Updated: January 31, 2024 Approved

Your car's water pump is an important part of your vehicle. It is the part that continually pumps coolant to your vehicle's engine so that it doesn't overheat. A leak or a faulty bearing can cause serious damage to your car's engine. Puddles of coolant underneath your vehicle or high temperature readings may be signs that your water pump needs replacing.

Steps

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If it's not possible to park it inside on a clean concrete surface, place a piece of light-colored cardboard underneath your car directly under the motor. Be mindful that water pumps are more likely to leak while the vehicle engine is running, so this is a poor reference for finding a leak.
If it appears to be wet from coolant, you have a leak somewhere, possibly in your water pump, but other sources of leaking coolant could be radiator hoses, heater hoses, freeze plugs, gaskets, or the radiator itself. To narrow the search down, try to place the cardboard directly underneath the water pump itself. If you notice green liquid on the cardboard, it's antifreeze. This means you have a coolant leak somewhere.^{[1]
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Find the round part at the front of your water pump that the belt is around. Attempt to rock the pulley back and forth. If it seems to be loose, it may be time to replace it, because the bearing is going bad.^{[2]
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Start your car's engine with the hood up. If you hear a low-pitched grinding noise, it may indicate that your water pump bearing is going bad. You can often hear it plainly if it's gone bad.^{[3]
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Research source} You also have similar bearings in your AC compressor, power steering pump, and alternator, so you need to be able to focus on the exact source of the sound, often difficult on a running engine.
If you see drops of water or a small stream, you have a leak. Many water pumps have a weep hole in front of the seal that will allow water to leak out if the seal is bad.
If your car is not circulating enough coolant due to a leaky or malfunctioning water pump, your engine temperature is going to increase, triggering the warning light.^{[4]
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This can be an indicator that your coolant reservoir is leaking or that you have a bad water pump. One other alternative is that there is a leak in the cooling system.

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Tips

A puddle of water found beneath your car on a hot day may not indicate a water pump or coolant system problem. When your air conditioning system runs in your car, condensation occurs. This condensation leaks out beneath your car and is perfectly normal.

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Sometimes there may be no leaking, and no bearing noise and everything else is in working order, i.e. fans, belts, hoses, thermostat, radiator, heater core, cap, etc. Except when it overheats it may have steam coming out of the cap, which is normal in most cases because the cap is designed to relieve excess pressure as a fail-safe for the other parts.

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Look for a small hole, this is the weep hole; it will leak when the water pump is going bad or has failed.

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The advice in this section is based on the lived experiences of wikiHow readers like you. If you have a helpful tip you’d like to share on wikiHow, please submit it in the field below.

If you have a bad water pump, your car's temperature reading might be normal for a while and then suddenly go higher. If your AC is on, you might feel hot air blowing out.
If you have a car from the car 1980s or older, the water should circulate through the radiator.

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Warnings

If your coolant is low and car is or has just been running, let it cool down before adding water or coolant. If the engine is hot, adding cool water can crack the engine block because of the drastic difference in temperature, turning your minor expense into a huge expense.

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Do not add 100% coolant to your vehicle, it will make it run warm and or overheat. Follow vehicle recommendation, generally 50/50 mix, some take up to 70/30. Never use pure water, as the boiling point of water is too low for modern engines.

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