Your car uses coolant for a number of purposes. It’s essential for keeping the engine within operating temperatures, as well as protecting the block from freezing temperatures. It’s also used to operate your car’s heater. While most vehicles only have a single water pump, some have a second pump, called an auxiliary water pump.
An auxiliary water pump differs from the primary pump in a number of different ways. First, it’s electronic, rather than belt driven. Second, it only works to pump extra coolant through the heater core. Here, it’s used to warm the air that blows into the cabin. Really, the only time the auxiliary water pump should operate is after you’ve turned the engine off but need to warm the cabin. The pump will run with the key in the on position, providing warmed coolant to the heater core.
In theory, your car’s auxiliary water pump should last the life of the car. However, it is an electronic component, and it is subject to failure at any point. Anything from a blown fuse to damaged wiring to a seized pump motor can render it inoperable.
What’s more, there is no set inspection for this pump. It’s not part of any regular maintenance service, and it is also not part of manufacturer specified scheduled services. With that being said, they are subject to wear and tear, primarily to the brushes in the motor. The cooling circuit itself may also be subject to damage (wiring damage, for instance).
Of course, if your pump fails you may not even notice it since it’s not part of normal vehicle operation. The only time a failed pump might present problems is during severe winter weather. Even then it won’t keep your vehicle off the road, but it could definitely lead to an uncomfortable experience if you attempt to work the heater without the engine running.
Obviously, you need to know a few signs and symptoms of impending failure (or if the pump has already failed). These include:
- Pump does not operate with the engine off and the key turned to on while the heat is running (you can’t hear the pump switch on)
- Coolant leaking from the auxiliary water pump
- No hot air from heater with the engine off and the key on
Having a failed auxiliary water pump isn’t a problem that will keep you off the road, but it does need to be addressed. Having a certified mechanic, such as one from YourMechanic, replace the auxiliary water pump is a simple convenient fix that will keep you warm during those cold winters.