Symptoms of a Bad Water Pump

Mia Bevacqua
March 1, 2018

Between all its moving parts and the fact that it burns fuel, it’s no surprise your engine gets hot when it’s running. This is where cooling system comes into play, and your water pump plays a key role in it. If the water pump fails, you’ll want to get it diagnosed by a mechanic quickly, as you run the risk of your engine overheating.

A faulty water pump can cause a number of problems:

1. Your engine overheats: If the water pump fails, your engine likely won’t get adequate coolant circulation, which will make it overheat. Overheating even once can cause extensive engine damage, such as a cracked cylinder head or block.

2. You notice a coolant leak: A leaking water pump shaft seal or mounting gasket can cause a low coolant level. You may see a puddle of coolant under your car or notice moisture under the hood.

3. Your car's heater doesn’t work: The car’s heater needs engine coolant to work properly. A low coolant level, caused by a leaking water pump, can result in an inoperative heater. A water pump that isn’t providing proper coolant circulation can also keep the heater from working.

4. You hear a growling noise: A faulty water pump bearing assembly can cause a growling or rumbling noise when the engine is running. Left unattended, the water pump may seize up, causing more problems.

What does a water pump do?

Your car’s water pump pushes coolant through the engine, hoses and radiator in order to keep the engine at an optimal temperature while it’s running. The coolant absorbs heat created during the combustion process in the engine and then releases it while traveling through the radiator.

The pump uses centrifugal force to send the coolant out and suction to pull it back in.

The water pump is usually mounted on the front of the engine and driven by the serpentine belt, or timing belt. A mounting gasket is used to form a seal between the water pump and the engine block.

Inside the water pump is an impeller — a centrifugal fan that’s designed to move water through your engine and cooling system. This impeller is attached to a shaft that’s supported by a bearing assembly. When the serpentine belt turns the water pump pulley, the impeller spins and pumps your coolant.

Get it diagnosed by a professional

Reasons why water pumps fail

Water pumps typically fail due to a broken impeller, bad bearing assembly or faulty shaft seal. These issues are usually caused by one of the following:

Time and mileage: Water pumps don’t last forever. In some cases, the pump may just wear out. This may be accelerated by a poor pump design.

Corrosion: Dirty or contaminated coolant can cause the pump shaft seal to fail prematurely. It can also eat away at the impeller blades or the impeller shaft.  

Running dry: The water pump is lubricated by coolant. If the pump is run dry due to a low coolant level, the shaft seal may get ruined.

» MORE: Get an accurate estimate for your car repair

What to do about it

Due to the overheating risk, a car with a leaking water pump should not be driven. Coolant leaks allow air into the cooling system, creating air pockets where hot spots can occur and damage other components. If the water pump is leaking, consider getting the vehicle towed to a repair shop.

Have a mechanic inspect your cooling system. If the water pump is the problem, it should be replaced, along with the water pump mounting gasket or seal. After the new pump is installed, the coolant level should be topped off and the cooling system bled of air. It’s also a good idea to have the thermostat swapped out at the same time, especially if the engine has overheated.

When replacing the water pump, the drive belts may need to be removed. The belts should be replaced if they show signs of wear.

The amount of disassembly and work involved in a water pump replacement varies greatly from car model to car model. This is typically a job best left to a professional.


Mia Bevacqua

About the Author

Mia Bevacqua is an automotive expert with ASE Master, L1, L2 and L3 Advanced Level Specialist certification. With 13-plus years of experience in the field, she applies her skills toward writing, consulting and automotive software engineering.

2 User Comments

Sign in to comment
By , February 01, 2018
Does anyone have a recommend parts list for replacing a Water pump on a dodge charger 09 2.7litre
By , November 09, 2018
Mia, I have a question...It may sound stupid but...I have a 2010 Ford Escape (Flex fuel) that would not shift in or out of gear. The tow truck driver was able to get it on the bed of the truck and then the car would shift. I took it to the Ford dealership, and their answer was it had a bad water pump. I have NEVER heard before, in my limited car experience, where a water pump would cause my car NOT to shift. Can you shed some light on this? I thought that maybe it could have been a flywheel gear issue.

Related Questions

See what others have asked about this, or visit the Questions page to ask your own question.
Which way to loosen pully to pull out water pump
How much should it cost to replace water pump?