How to Tell If Your Car’s Water Pump Needs to Be Replaced
If coolant is leaking underneath your car, or your temperature reading is too high, it’s possible your car’s water pump needs to be replaced.
Park Your Car Overnight
If you are unable to park your car in a garage with a clean concrete floor, place a piece of light-colored cardboard directly under the car’s engine. Note that the water pump is more likely to leak when the engine is running, so it is not advisable to check for leaks while the engine is running.
Check the Cardboard the Next Morning
If the cardboard is wet from coolant drippings, there’s a leak somewhere, most likely the water pump. Other places where coolant leaks may occur are the radiator hoses, heater hoses, freeze plugs, gaskets, or the radiator itself. To narrow it down, place cardboard directly under the water pump. If you find green liquid on the cardboard, it is antifreeze. This means the coolant is leaking somewhere.
Check Water Pump Pulley
Check the round piece on the front of the water pump where the belt goes around. Rock the pulley back and forth. If it is loose, the pulley will need to be replaced as the bearings will be damaged.
Listen to the Sound of the Car
Open the hood and start the engine. If you hear a low friction noise, the water pump bearing may be broken. If it’s broken, the sound will be obvious. There are similar bearings in air conditioning compressors, power steering pumps, and alternators, so be sure to listen clearly to where the sound is coming from. It is generally difficult to hear if the engine is running.
Check for Leaks around the Water Pump
If you see water droplets or water flowing out, there is a leak. Many water pumps have drain holes in front of the seal. If the seal is broken, water will leak out from the drain hole.
Pay Attention to the Temperature Warning Light
If the car is not circulating enough coolant due to a leak or water pump failure, the engine temperature will rise and the warning light will turn on.
Check Coolant Warning Light
If it comes on, the coolant reservoir may be leaking, or the water pump may be broken. Another possibility is that there is a leak in the cooling system.
Tips
- If you find a puddle of water under your car on a hot day, it does not mean there is a problem with the water pump or cooling system. There will be condensation when the car’s air conditioning system is running. It’s completely normal for condensation to leak out from under your car.
- Look for small holes, also known as weep holes. If the water pump is broken or has failed, leakage will occur in the weep hole.
- There may be times when there are neither leaks nor bearing noise and everything i.e. fan, belts, hoses, thermostat, radiator, heater core, cap, etc. are functioning properly. Except for the steam coming out of the cap when overheating, this is usually normal because the cap is designed to relieve excessive pressure and is a fail-safe device that protects other components.
- Some water pumps use plastic impellers to push coolant, and some coolants are corrosive once the additives are exhausted (coolant should be replaced every three to seven years to prevent engine damage when the additives are exhausted). The water pump impeller will wear out and be unable to move coolant, so the car will get too hot. Take off the radiator cap and do a cold start to test if this is true. You should be able to see the fluid moving inside the radiator. If you can’t see it, the internal water pump blades are likely gone or only a small part remains. However, if there is a thermostat in the car, such a test is meaningless, because the coolant will only circulate when the thermostat is open at operating temperature, and you certainly don’t want to open the radiator cap at operating temperature.