Bad Water Pump Symptoms, Causes, and How To Test It

The water pump in a car plays a vital role in the vehicle’s cooling system. It is used to circulate the coolant throughout the engine. A bad water pump may lead to different serious issues. This article explains the bad water pump symptoms, causes, and how to replace it.

Function of Water Pump

The water pump is used to circulate coolant through the vehicle’s engine block, hoses, and radiator and effectively draw heat away from the system. With a well-functioning water pump, the engine maintains a stable temperature.

When the coolant flows from the radiator to the engine, it absorbs the heat of the engine parts. It then releases this heat as it cycles back through the radiator, permitting the cooled fluid to again enter the engine. Without this cooling mechanism, the engine risks overheating.

In most vehicle models, the engine drives the water pump using a belt. The pump’s shaft is attached to blades that spin in sync with the shaft. This rotation generates a suction that draws coolant from the radiator.

Upon reaching the pump, the centrifugal force propels the coolant towards the outer wall and into a channel leading to the engine block. The coolant flows from the cylinder head before returning to the radiator, where it cools down and is ready to start the cycle again.

Symptoms Of a Bad Water Pump

When the water pump of your vehicle goes bad, it produces one or more of the below-given symptoms:

1) Leaking Coolant

A coolant leak is one of the major symptoms of a bad water pump. This leak might originate from the water pump gasket, where it attaches to the engine, or potentially from the water pump shaft seal.

However, the bottom line is that any coolant leak reaching the ground from the engine signifies a significant issue. Thus, it would be wise to consider changing both the pump and its gasket.

In cases of a small leak, there may not be a visible pool of coolant under the car. Instead, you might see a streak of white residue, tinted with the color of the coolant, where the leak is evaporating on the hot engine surfaces before reaching the ground. This residue traces the path of the leak down the front of the engine.

In the process of remedying this issue, it might also be necessary to replace the serpentine belt, the water pump pulley, the timing belt, or even other engine seals.

2) Engine Overheating

The engine overheating is one of the clear signs of a faulty water pump.

The coolant plays a crucial role in maintaining the engine’s temperature within the normal operating parameters. If you notice the temperature gauge escalating and the engine overheating, it could mean that the coolant is not properly cooling your engine.

However, there are numerous potential causes of engine overheating, such as an air bubble trapped in the coolant system, contaminated coolant, coolant leaks, insufficient engine oil, or a faulty engine sensor.

If, upon investigation, the water pump is identified as the problem, several things could have gone wrong. It could simply be a case of the water pump having aged or become worn out. Alternatively, the impeller of the pump could be damaged due to freezing temperatures or the intrusion of contaminants.

Regardless of the cause, driving a vehicle with an overheated engine can cause catastrophic outcomes, such as a cracked cylinder head, a seized engine, or a blown head gasket.

3) White Smoke from Engine

If you notice white smoke emerging from your vehicle’s radiator, it’s highly likely that your engine is overheating. This could be due to a malfunctioning water pump, but an ineffective radiator cap may also be the culprit, leading to coolant leakage.

Regardless of what’s leading to the emission of steam, it’s crucial that you stop your vehicle right away. Driving with an overheated engine, even for a brief span, is never a wise choice. It can quickly lead to irreversible damage to the engine, necessitating a complete replacement.

4) Squealing Noise

An unusual sound, such as a chirping or squealing sound emanating from the engine’s front, can often signal a water pump nearing the end of its service life. This noise might be similar to the sound made by a noisy serpentine belt, and in several instances, that’s precisely the cause.

Excess friction from the water pump can make the belt slip against the pulley, typically producing a rhythm that corresponds with the engine’s RPMs.

This issue is often attributed to a deteriorated shaft bearing. While the water pump may continue to function in this condition for weeks, months, or even longer, there’s also a risk it could fail abruptly by seizing. Thus, even though this sound may be an early warning sign of a water pump going bad and could be intermittent, it should never be disregarded.

5) Unstable Engine Temperature

It’s less frequent, but you might observe the engine temperature gauge oscillating between high and normal. If your pump is unable to properly circulate the coolant, the engine will begin to overheat.

But there might be a minor decrease in temperature if you’re driving at high speeds due to increased air circulation. Regardless, if the temperature gauge ever approaches critical levels, it’s crucial to get your cooling system inspected.

Causes of a Bad Water Pump

Your car’s water pump may go bad due to one or more of the below-given causes:

Damaged Seal
Worn Out Axle
Coolant Contamination
Misaligned Drive Belt
Loose Water Pump Pulley
Corrosion In the Cooling System

1) Damaged Seal

A deteriorated or damaged seal may result in coolant leakage or even fluid contamination. Consequently, your water pump might fail to uphold an adequate coolant flow, potentially causing the engine to overheat.

2) Worn Out Axle

The serpentine belt propels the water pump, facilitating the circulation of coolant throughout the engine. However, a worn-out water pump axle might result in a slack belt, hampering the efficiency of the water pump and consequently disturbing the flow of the coolant.

As a result, your engine could overheat, which badly leads to a cracked engine block or cylinder head.

In order to verify this, it would be necessary to remove the serpentine belt and inspect for any indications of axle damage. The placement of the serpentine belt within the engine bay can vary depending on the engine’s design, either situated at the front or along one side. Additionally, if there are any covers on top of the engine, they would also need to be taken off.

Read More: How To Fix An Axle Seal Leak?

3) Coolant Contamination

If the coolant in the system becomes contaminated, it can cause corrosion and damage to the water pump. This is why it’s important to regularly change your coolant and use the type recommended by your vehicle’s manufacturer.

4) Misaligned Drive Belt

If a drive belt is overly tight, it may start to put excessive stress on the bearings of the water pump, causing early failure.

On the other hand, if the belts are too loose, there may not be enough tension to rotate the pulley effectively and circulate coolant throughout the engine. Therefore, unless the belt is appropriately adjusted, it could result in a water pump that fails to function properly.

5) Loose Water Pump Pulley

The bearings of the water pump pulley can become slack over time. This can diminish the pump’s performance. Furthermore, the pulley’s unstable state may cause the water pump’s impeller to lose balance, leading to a total breakdown.

6) Corrosion In the Cooling System

Corrosion can occur when the coolant mixes with other substances or tap water, resulting in contamination. This can cause the water pump to develop rust holes, rendering it entirely non-functional.

Water Pump Location

A water pump is often situated close to the serpentine belt or drive belt, placing it towards the front of the engine. However, when the water pump is driven by the timing belt, its location may be more elusive. In such cases, you might have to detach certain parts or covers to access it.

The surest way to ascertain the location is to consult a service manual or look for a diagram online. Being aware of the water pump’s location can help you determine whether to attempt a DIY replacement or seek the assistance of a professional mechanic.

Water Pump Replacement Cost

The replacement cost of the water pump depends on the vehicle model and brand type. The average replacement cost of the water pump is between $540 and $920. The cost of the water pump itself is between $340 and $520, while the labor cost is between $200 to $400.

How To Test a Water Pump?

Follow the below-given steps to test the water pump of your car:

Ensure that your vehicle is parked on a flat surface.
Turn off the engine and allow it to cool down before proceeding with any work on the cooling system.
Carefully examine the water pump pulley. Gently move it back and forth to check for any signs of movement. Ideally, there should be no noticeable play. If you detect any movement, it may indicate the need for a water pump replacement.
Inspect the cooling system for any signs of leaks. Identifying the source of coolant leakage can help determine if the water pump is responsible. Look for leaks originating from the water pump housing or around the gasket. If there is evidence of a leak, it’s advisable to replace the water pump.
Check the coolant reservoir for any indications of a leak. A lower coolant level in the reservoir could suggest a leak. Additionally, leaks may occur at the water pump gasket, especially if the fluid is contaminated due to the absence of a coolant flush.

FAQ Section

How many hours does it take to replace a water pump?

The length of time it takes to replace a water pump can vary greatly. If it’s a straightforward replacement, it might only take around two hours to install a new one. However, if there are additional components that need to be disassembled to reach the water pump, the process could potentially take up an entire day.

How long can I drive a car with a bad water pump?

Once you’ve identified that your car’s water pump is defective, it’s crucial not to operate the car. The faulty pump will be unable to maintain coolant circulation, which is necessary for the engine to remain within safe temperature ranges. As a result, your engine can overheat, potentially causing severe damage that could necessitate an engine replacement.

Can I drive a car with a bad water pump?

Driving your car without a functional water pump is technically possible, but it’s not advisable. Once the water pump fails, it results in improper coolant circulation throughout the vehicle. This can cause the car to start overheating. When overheating occurs, the engine can suffer irreversible damage, and this can happen rather quickly. So, it’s best not to risk it.

How long does a water pump last?

For most contemporary vehicles, it is generally advisable to replace the water pump every 60,000 to 100,000 miles. If your vehicle model is just new, this isn’t something you’d typically need to be concerned about. But if you’re driving an older vehicle, it’s a good idea to raise this issue with your technician for regular checks.

What does a faulty water pump sound like?

A malfunctioning water pump can usually be identified by a distinctive squealing or chirping noise emanating from the engine’s front. This sound is similar to the one produced by a serpentine belt. In some instances, this noise is a result of the extra strain placed on the drive belt due to issues with the water pump pulley.

What happens when a car water pump goes bad?

In the event of a water pump failure, there might be an inadequate supply of coolant circulating through the engine. This deficiency may cause the engine to exceed its normal operating temperature and overheat, potentially leading to the breakdown of the engine gasket, cylinder head, and other integral parts. If not addressed promptly, this could escalate to the point where your engine sustains significant damage, necessitating a complete overhaul.

Does the water pump affect AC?

No, a water pump doesn’t affect the AC performance of your vehicle. This pump moves the coolant through the engine for efficient cooling while your AC is on or off.

How to tell if your water pump is bad?

When a water pump goes bad, it produces different symptoms such as coolant leakage, engine overheating, white smoke from the engine, or squealing noise. When the water pump goes bad, it doesn’t properly circulate the coolant through the engine which leads to overheating.

Can a bad water pump cause a rough idle

Yes, a bad water pump may cause your vehicle to go through rough idle.

Written By

Engineer Rahela

Rahela is the owner and main author of Mechanicalspecial. She is an automotive expert writer. She have over four years of experience in the automotive writing niche and have completed over 700 pieces of content from 40 projects. She have good knowledge and skill in vehicle repairing, all mechanical work, car upgrades and maintenance.