Auxiliary Water Pump Buyer's Guide
- A vehicle’s auxiliary water pump is an electric pump that sends additional warm coolant to the heater core. This component helps regulate a vehicle’s cabin during cold days and makes it possible for the heater to work.
- The job of the auxiliary water pump is to provide enough volume of coolant to keep the heater core warm.
- The main cause of auxiliary water pump failure is age and wearing of the electric motor. Overheating and low coolant levels can also affect the pumps’ performance.
- If your heater is not producing constant warm air, especially when you’re driving in stop-and-go traffic or low speeds, it may indicate that there is an issue with the vehicle’s auxiliary pump function.
- Though other symptoms may manifest, it’s best to contact a trusted mechanic and do a thorough diagnosis of the problem instead of instinctively replacing parts such as the thermostat and the heater core.
- A replacement auxiliary water pump can cost you anywhere from $20 to $780.
Performance isn’t the only thing that defines a vehicle. Comfort matters too. Making sure the cabin stays at a desirable temperature is a job for your vehicle’s climate control system, heating, ventilation, and air conditioning (HVAC) system, or both.
These two systems are made up of complex sensors and components that work together in setting the best driving conditions. Without your heating, AC, or your climate control system, it’s impossible for someone to drive through the heat of summer and the cold of winter without discomfort.
An auxiliary water pump is an important component that helps keep the cabin warm, especially in the colder months. What is this part and how does it work? If you have an auxiliary pump already, when do you know that it’s time to replace it? Answer these questions and more with this informative guide.
What is an auxiliary water pump?
A vehicle’s auxiliary water pump, or auxiliary pump, is an electric pump that sends additional warm coolant to the heater core. This component helps regulate the vehicle’s cabin during cold days and makes it possible for the heater to work. However, it must be noted that not all vehicles have an auxiliary water pump.
The auxiliary water pump is not connected to engine cooling. Some people may associate the auxiliary water pump with the engine’s water pump. The “primary” water pump sends coolant throughout the engine to keep it at its desired operating temperature. However, unlike the auxiliary water pump, it is activated by the drive belt.
How does an auxiliary water pump work?
Diesel engines usually do not produce enough heat when running or idling. This, combined with lower engine speeds, makes it easier for the coolant in the heater core to lose most of its heat before it’s blown into the cabin. Drivers then complained of insufficient heating within their vehicles, especially in stop-and-go traffic or at cruise speeds with lower rpm. The job of the auxiliary water pump is to provide enough volume of coolant to keep the heater core warm.
The auxiliary water pump is regulated by the vehicle’s computer using information obtained from several sensors and modules in the vehicle. It considers various factors, such as the vehicle’s speed, engine rpm, coolant temperature, blend door position, fan speed, exterior and interior temperatures, and the temperature selected on the AC control head.
Auxiliary water pumps were first used on Mercedes-Benz diesel-engine vehicles in the 1980s. However, they eventually also used these pumps on gas-powered vehicles like the C- and S- class as well. In fact, Mercedes-Benz, Audi, and BMW, among others, use this pump as part of the automatic temperature control system to keep the cabin heated for short periods of time even after the driver has turned off the ignition.
Why do you need an auxiliary water pump?
The auxiliary water pump does have much of an effect on your vehicle’s performance and drivability. However, if it fails, it may cause a huge inconvenience, especially if you’re on the road in the cold winter months.
How does an auxiliary water pump fail?
The main cause of auxiliary water pump failure is age and wearing of the electric motor. As with all rotating electrical devices, several components of the auxiliary water pump may fail, including the brushes and the windings.
Another contributing factor to this part’s failure is overheating. If the motor on the auxiliary water pump overheats, it can accelerate the pump’s failure. Excessive heat can cause the coolant to expand and generate a pressure build-up in the system. This pressure can then force coolant past the shaft seals and cause a leak.
Low coolant levels can also cause the auxiliary water pump to fail because of its position. The auxiliary water pump is typically located high in the system, either on the firewall or in the strut tower.
Auxiliary water pump failure symptoms
When an auxiliary water pump fails, it will not affect other HVAC components. Neither will it affect the operation of the rest of the air conditioning system. It will only affect the production of heat. Below are some of the most common symptoms of a bad auxiliary water pump:
Heater does not release warm air
There may be an issue with your vehicle’s auxiliary water pump if you notice that no warm air is coming from the heater. Because of either wiring issues or motor failure, the pump cannot send hot coolant to the heater core. This makes it difficult for warm or hot air to enter the cabin of your vehicle.
Heater does not produce warm air in stop-and-go traffic
Fluctuating heat may also point toward a faulty auxiliary water pump. You might also notice that the heater is performing poorly at low speeds and when the vehicle is at idle.
Low coolant reservoir
At times, low coolant levels might be the only indication that the auxiliary water pump has gone bad. Auxiliary water pumps can leak coolant when they fail, just like a standard water pump would. These leaks often go unnoticed.
Other symptoms may also manifest an ineffective cabin heating system or a diagnostic trouble code (DTC) registering in your vehicle’s memory. Scan tools can test the auxiliary pump function in most vehicles. However, it’s still best to consult a trusted mechanic once you notice issues with your vehicle’s heating. Proper diagnosis is important so you can arrive at an appropriate fix, instead of just impulsively replacing the thermostat, the water pump, or the heater core.
How much is a replacement auxiliary water pump?
A replacement auxiliary water pump can cost you anywhere from $20 to $780. The price of the replacement auxiliary water pump depends on its compatibility with your vehicle’s year, make, and model. Other factors that affect its cost include the seller’s location, brand, series, and quantity. Auxiliary water pumps are usually sold individually.
Finding the right fit
CarParts.com offers a wide variety of reliable and durable auxiliary water pump replacements. To get started, you can use the site’s vehicle selector tool to indicate your vehicle’s specific year, make, and model. After that, you can also use the site’s search filters to indicate your location and quantity preferences as well as your price range. Looking for a quality replacement part has never been this easy.
The Right Auxiliary Water Pump to Cool Your Engine
If you're craving for a cool breeze once you enter your car, you just simply turn on your AC to full blast. But what if your engine's the one that needs cooling? Then it is the auxiliary water pump's turn to keep it comfortable. The auxiliary water pump, a part of your engine's cooling system, is responsible for the consistent flow of coolant into your car's heater core. Its importance to your engine's everyday function is simple and straightforward, but choosing the perfect one for your car isn't. Here are a few dos and don'ts when it comes to shopping for a new auxiliary water pump:
- Choose an auxiliary water pump that is made of sturdy material, such as high-grade steel. Since the water pump is at the part of the engine where it is most exposed to high temperature, it must be able to withstand the nature of its environment. Also make sure that it is corrosion and rust resistant to prevent premature wear of your auxiliary water pump.
- Inspect your preferred auxiliary water pump before purchasing it. Unlike other parts of your engine cooling system, it is more complex because of its electric component. Make sure that aside from looking through the seals, bearings, and the pump's other hardware, you should also check its internal electric parts.
- Invest in a name brand auxiliary pump rather than purchasing cheap aftermarket products. This will not only ensure the pump's consistent quality, but it can also guarantee a perfect fit. Since no modifications are needed to fit an OE auxiliary water pump to your system, you can also save time and money on installation.
- Don't replace your auxiliary water pump with a second-hand part. Although this is a cheaper option, it is also the most unreliable one. Second-hand or refurbished auto parts can be a dangerous addition to your system. It carries an unknown amount of mileage and you basically don't know what it has gone through before reaching your car. Busted bearings may have been welded together or other parts may be replaced with substandard ones. These minor kinks in refurbished pump could result in unnecessary damage to both your radiator and engine.
- Don't be stingy about replacing an auxiliary water pump. Opt to get an extended warranty. Purchasing an extended warranty plan has many benefits that can add more value to your water pump. There are a lot of suppliers that offer a reasonable extended warranty plan. Be sure to read through the different limitations and conditions of the plan before you decide which one's best for you. Scrutinize it thoroughly to ensure that the extra insurance that you're paying for will not go to waste.
Replacing an Auxiliary Water Pump
Is your engine overheating more than usual? Did you notice coolant leaking from underneath your car? Does warming up the insides of your car taking up more time than usual? If you answered yes to all these questions, then you've got a faulty auxiliary water pump under your hood. Save time and money by replacing this part by using a few simple tools and this easy-to-follow guide.
Difficulty level: Moderate to difficult
Tools you'll need:
- Metric socket set
- New auxiliary water pump
Step 1: Preparing your car
Before working on anything under your hood, always remember to disconnect the negative terminal of your battery. Using a wrench, unbolt the negative cable from its terminal.
Step 2: Gaining Access to the auxiliary water pump
There are a few components of the engine compartment that needs to be taken out to access your auxiliary water pump. Start with your air filter box. If there are screws that hold the air filter, undo them and pull out the manifold. You should also unfasten the coolant reservoir tank and the side engine covers to get to the pump.
Step 3: Removing the engine manifold
Aside from the parts removed in step 2, you also have to slightly prop up your engine manifold to get to your pump. Loosening the manifold varies according to your car's make and model. Refer to your vehicle's manual to see which bolts and clamps hold the manifold to your car's frame. Carefully remove each one until you can lift the engine manifold just enough to reach your pump.
Step 4: Disconnecting the pump
Once you get to the auxiliary water pump, disconnect it from the harness connector. Take out the coolant hose that is attached to the pump as well.
Step 5: Removing the pump
Using a socket wrench, remove the heater valve and the auxiliary water pump from the mounting. Unbolt the nuts to release both parts.
Step 6: Separating the pump and heater valve
Once you've removed both the heater valve and water pump, unfasten the clamp that holds the two parts together. Pull out the clamp from the water pump to completely disconnect it from the valve.
Step 7: Installing new water pump
Taking your new auxiliary water pump, connect it to the heater valve and secure them together using the clamp.
Step 8: Reassembling the engine manifold and finishing touches
Follow steps 1 to 5 in reverse order to complete the installation.