A car's water pump is an important part of the vehicle. It is the part that constantly pumps coolant to the engine so that it does not overheat. A leak or defective bearing can cause serious damage to your car's engine. Puddles of coolant under the car or an increased temperature of the engine can be signs that the water pump needs to be replaced.
Step 1. Leave your car parked overnight in a garage with a light concrete floor
If it is not possible to park the car inside on a clean, concrete surface, place a piece of light-colored cardboard under your car, directly under the engine. Be aware that a water pump usually only leaks when the engine is running, so this is not a reliable way to find a leak.
Step 2. Examine the cardboard the next morning
If it appears to have gotten wet with coolant, you have a leak somewhere. Possibly in the water pump, but it could also be another leaking part such as the radiator hose, heater hose, freeze cap, gaskets or the radiator itself. To limit the possibilities, you can try placing the cardboard directly under the water pump itself. If there is green liquid on the cardboard, it is antifreeze. This means that there is a coolant leak somewhere.
Step 3. Check the water pump pulley
Locate the round part on the front of the water pump that has the belt around it. Try to move the pulley back and forth. If it appears to be loose, it may be time to replace it as the bearing is wearing out.
Step 4. Listen to the sound your engine makes with the hood up
If you hear a low, grinding noise, it may mean your water pump bearing is worn out. You often hear it quite clearly. There are similar bearings in the AC compressor, power steering pump and alternator, so be sure to find out the exact location of the noise. This is often difficult while the engine is running.
Step 5. Check for leaks around the water pump
If you see water droplets or a small trickle of water, you have a leak. Many water pumps have a seal hole through which water can leak if the seal is worn.
Step 6. Notice if the temperature warning light comes on
If the circulation of coolant in the car is not sufficient due to a leak or faulty water pump, the temperature of the engine will increase and the warning light will come on.
Step 7. See if the low coolant warning light comes on
This could be an indication of a leak in the reservoir or a defect in the water pump. Another possibility is that there is a leak in the cooling system.
- A puddle of water under the car on a hot day does not necessarily mean that there is a problem with the water pump or the coolant. When the air conditioning in the car is on, condensation forms. This condensation leaks out under the car, this is completely normal.
- Look for a small hole in the water pump, this is a check hole. It will leak if the water pump is worn out or faulty.
- Sometimes there is no leak, no grinding noise and everything else (fans, belts, hoses, thermostat, radiator, heater, cap, etc.) works normally. Steam only comes out of the cap when the car overheats. This is normal in most cases as the cap is designed to release excessive pressure to protect the other parts.
- Some water pumps have plastic impellers that move the coolant. Coolant is corrosive when the additives are gone (the coolant should be replaced every 3 to 7 years to prevent engine damage when these additives are gone). The water pump impellers can wear out and stop moving coolant, causing the car to overheat. To test this, start a cold engine without the radiator cap; you should see the coolant move slightly in the radiator. If not, there is a chance that the internal impellers are corroded or very small. However, if you have a thermostat in your car, this test is not helpful. Coolant then does not circulate until the thermostat is at working temperature, and at this temperature you do not want to touch the radiator cap.
- If the coolant level is low and the engine is still running or has just run, allow it to cool before adding water or coolant. Adding water while the engine is hot can cause the engine block to break due to the large temperature difference, turning a small problem into a very big one.
- Do not add 100% coolant, the vehicle will overheat. Follow the directions for your vehicle, usually a mixture of 50/50 and sometimes 70/30. Also, never use only water, as the boiling point of water is too low for modern engines.