An internal combustion engine produces significant amounts of heat. In all modern car engines, this heat needs to be controlled and this is done with water. The water pump then is a vital component. 

In this article, we’ll explain a little about what it does, and why it's important to be able to check if the water pump in your car is failing. 

What does the Water Pump do? 

A car's water pump cycles water from the radiator, through the motor and back again, in order to keep the engine at a constant temperature.  

As mentioned, the action of burning fuel inside an engine creates a lot of heat. Typically engines run at around 80-100°C. 

The coolant system uses fluid to move heat from the engine to the outside air. It does this by passing the hot water through the radiator. Car radiators are positioned to allow maximum flow of air over them, reducing the temperature of the coolant.  

The coolant then flows back through the engine and cools the entire system, the type of coolant depends on your climate and engine type. The water pump is what makes this fluid flow. 

How to check for water pump failure 

If you’re concerned about your car’s water pump, there are symptoms to look out for. We’re going to go over the main signs of water pump failure. 

1. Overheating 
2. Leaks 
3. Smoke Coming From Radiator 
4. Whining Or Scraping Noise

The first and foremost thing to check is engine temperature during operation. Many cars have a gauge with an acceptable temperature level and a red or dangerous level.

Ensure the needle of the temperature gauge never enters the red zone, if it does, stop driving the car immediately, as excessive overheating can cause serious damage. 

Find out What to do if your car is overheating 

Leaks 

Check under the vehicle before and after every trip. It may be necessary to open the bonnet and look around the sides of the engine to spot any wet patches or recently damp areas.  

Bear in mind the engine will have been hot enough to evaporate small drips. Patches of rust around the pump are also an indicator it has been dampened at some point.  

It might be helpful to place a plain piece of cardboard or paper under the engine after you park up. Held down with some weights, this will make any drips very easy to spot, especially if you park your car on gravel. 

Smoke Coming from Radiator 

If the water pump is damaged, and the coolant is not flowing properly, it may boil and exit the system as steam at the expansion tank or radiator.  

If the engine has overheated to this point, do not drive any further than is absolutely necessary, more heating could damage the engine irreparably.  

Whining or scraping noise 

If you have started to notice a noise such as scraping, or whining from the side of the engine, this too could be the water pump failing. In any case, any such car noises should be properly investigated and the car not driven until fixed. 

How much does a water pump replacement cost?  

On average, you can expect to pay between £250-700 for a replacement water pump. Of course, the cost will vary depending on your car’s age, make and model.  

If you're worried about car repair costs, Bumper can help. We've teamed up with trusted partners around the UK to offer 0%-interest car repair loans.

How critical are the cooling system and water pump 

As we’ve discussed, coolant is used to move heat away from the engine, so what happens if your water pump fails?  

Without cooling, an engine can quickly reach 150°C and beyond. At these temperatures, plastics around the engine will begin to soften and become weak and wiring will melt and cause shorts, but most terminally, metal engine components can warp.  

The head and block are the two main components of an engine, between them is a head gasket, which seals against the pressure of the combustion chambers or cylinders.  

If the head becomes warped, it is likely a loss of pressure in the cylinders will result. The level of pressure in a cylinder is known as ‘compression’ and head warping and head-gasket failure are common causes of low compression.

Low compression will make the engine run poorly and inefficiently, and in many cases not run at all. A vehicle that has suffered a warped head or head gasket failure cannot be driven. 

Find out how much a head gasket replacement costs.

When to replace your water pump 

If you experience any of the problems listed above or have noticed any of the warning signs, it's important to get your car checked over as soon as possible. Water pump failure can lead to irreparable damage to the engine, and it will leave the car stranded. 

When repairing the water pump it’s recommended to change your cam belt if you have one. On many cars with a cambelt, the belt needs to be removed to change the water pump, so it makes economical use of the labour time to do both at once. 

If you need any assistance with car servicing and repair costs, enter your vehicle registration and postcode with Bumper and apply for interest-free monthly instalments for maintenance invoices. 

Author - Joseph Law

Joseph has been writing about cars for over seven years and writing for Bumper for over two, blending his passion for automobiles with a talent for storytelling.

Joseph has written about engineering and cars for Autozilla, Komaspec, and several engineering manufacturers. When he's not writing or tinkering with one of his five cars, Joseph dreams of owning an Alfa Romeo 33 Stradale.