Skip the auto shop - Our mechanics make house calls

Symptoms of a Bad or Failing Water Pump (Auxiliary)

water pump auxiliary

Bad or Failing Water Pump (Auxiliary) Inspection

by a top-rated mechanic at your home or office

Many of today's modern cars utilize a standard water pump to keep their engines at a consistent operating temperature. Their single pump system circulates coolant from the radiator, through the engine block, to a heater core, and then back to the radiator. However, it is common for many vehicles, especially heavy duty pick-ups to have an auxiliary water pump that will expedite the process.

An auxiliary water pump is different than a single water pump in that it is an electrically controlled motor. Its primary use is circulating water by way of a bypass hose from the main coolant lines to a heater core that is used to collect heat and distribute warm air into your vehicle when the heater is turned on. A failing auxiliary water pump will not typically keep you from driving your vehicle, it can definitely affect your comfort in the winter and in severe cold conditions. If not repaired or replaced, it could be dangerous to drive if the pump is failing or has completely failed.

There are a few common warning signs that you should be aware of that might indicate a problem with your auxiliary water pump exists and that it has reached the end of its service life.

HAVE SYMPTOMS OF CAR TROUBLE?
Get an $80 diagnostic
by a top-rated mechanic at your home or office.

Get a quote · Book an Appointment · Our expert mechanics come to you.

1. No warm air is coming from the heater

Since it is the primary job of an auxiliary water pump to supply hot coolant to the heater core, it seems obvious that the first symptom of a problem with this component would be no hot air blowing from the heater. The auxiliary water pump moves hot water or coolant that has recently circulated through the engine block to the heater core. However, when the pump is not working, due to an electronics failure or the motor of the auxiliary pump being broken, the heater core will not be able to heat up. If this does not occur, it's impossible for hot or warm air to enter the cab of your vehicle.

When you turn on the heater and notice that no hot or warm air is blowing into the cab of your car, truck or SUV, you should contact a mechanic to inspect this problem. Note: your engine needs to be at operating temperature in order for the heater core to develop enough heat to blow into your cab. Wait for the engine to warm up before calling the mechanic in this instance.

2. Heater has fluctuating heat

The auxiliary water pump is a consistent flowing device that circulates warm coolant into the heater core – regardless of how fast your engine is running. Because of this fact, if you set a temperature on the thermostat control (if your car has one), it should remain solid. If you notice that the temperature inside your vehicle seems to increase or decrease based on your driving, especially if you notice a temperature decrease when the vehicle is idling, this could be caused by a faulty auxiliary water pump. Contact a mechanic to inspect the water pump or the heater core to see if there is damage to this component.

HAVE SYMPTOMS OF CAR TROUBLE?
Get your car fixed at your home or office.

Get a quote · Book an Appointment · Our expert mechanics come to you.

3. Window defrost is not working

Windows tend to fog up when the temperatures outside are very cold or if there is excess humidity inside of the car. To defog or defrost the windshield, vehicle owners will turn on the windshield defrost button, where warm air from the heater core will blow onto the windshield so you can clearly see outside and drive safe. This application is powered by hot water that is supplied by the auxiliary water pump in many vehicles. If you turn the defroster on and the windows don't defrost rather quickly, it's possible that you have a broken auxiliary water pump.

4. High pitched buzzing sound from under your dashboard

The auxiliary water pump is typically located at the rear of your engine, where the main water line splits to supply the heater core with recently heated coolant. On rare occasions, the auxiliary water pump will experience an electrical problem where the pump runs faster than it should or will continue to run after you've turned the engine off. This is caused by an electrical short in the wiring that powers the auxiliary water pump. The water pump will make a high pitched buzzing sound if this occurs.

If you recognize any of the above warning signs or symptoms, contact your local ASE certified mechanic as soon as possible so they can inspect the problem and replace your auxiliary water pump if needed.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Still not sure about your car's issue?
Diagnose your car
What kind of issue are you experiencing?
Brakes are squeaking
Car is not starting
Car is overheating
Car is shaking (vibrating)
Fluids are leaking
Heating and A/C
Smoke or steam is coming out of the car
Warning light is on
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...


Related questions

Q: How do I know if my water pump has went out?

Hello, a coolant pump can fail three different ways: leaking, noise, or low to no flow of coolant. Leaking would be associated with a loss of coolant and needing to add coolant back into the system. This could also be...

Q: Reduced engine power warning on, disabled throttle

There is a common issue among vehicles of this year model with the throttle position sensors on the throttle bodies. The reduced engine power warning may have also illuminated the Check Engine Light and stored a faults code. I suggest...

Q: How to take air out of cooling system Lexus ls400 1997?

Hi there. First check the cooling system for the right amount of coolant and top it off if its low. Then run the cooling system until the engine is hot at operating temperature. Shut off the engine and let it...