Engines with electric auxiliary pumps become more efficient, as they generate less excess heat and oil consumption. Even though not all vehicles have one yet, these pumps are growingly popular in modern, low-emission and high-output engines that have to run within a small temperature range in order to maintain their efficiency.

The usefulness of an auxiliary electric water pump

So, what is an auxiliary water pump? It is a secondary pump that plays a crucial role in maintaining engine efficiency and passenger comfort. These pumps can send hot coolant into the heater core regardless of the engine’s RPMs, providing hot/cold air to the cabin even when the engine is idling or off. The auxiliary coolant pump can continue to operate while the car has stopped, allowing coolant to circulate and fully dissipate the heat from the supercharger.

This type of water pump is essential for passenger comfort, since it allows for sufficient heating even when passengers are driving in traffic or at low RPM. Also, many modern cars use this second pump to allow you to use the air condition for a period while the engine is off. 

Note that unlike the main water pump, this one is not running all the time. The electronic control unit will regulate the auxiliary pump according to the needs of the moment.

To sum up, some of its unique advantages include:

• Facilitates demand-driven cooling of the vehicle.
• Saves on fuel.
• Enhances passenger comfort.
• Is efficient in cooling down power train components.
• Reduces emissions.

Auxiliary electric water pump diagram

Understanding the auxiliary electric water pump diagram is essential to grasp how this component integrates into the vehicle’s cooling system. This pump is typically located near the heater core or within the engine bay and operates as part of the broader coolant circulation system.

A standard auxiliary electric water pump diagram includes the following key components:

• Main coolant lines – Transport coolant throughout the engine.
• Heater core – Receives heated coolant to provide warmth to the cabin.
• Bypass hose – Allows the auxiliary pump to circulate coolant independently.
• Electronic Control Unit (ECU) – Regulates pump operation based on temperature and vehicle conditions.
• Electrical connections – Power and control the auxiliary water pump motor.

The pump activates based on inputs from the BCM (Body Control Module), ensuring coolant circulation even when the engine is off or idling. This contributes to passenger comfort, fuel efficiency, and optimal thermal management of powertrain components.

For a detailed diagram specific to your vehicle, always refer to the manufacturer’s service manual.

Related content: Peculiarities of an auxiliary water pump

Reasons to change your auxiliary electric water pump

The main reason these pumps fail is the electric motor’s natural age and wear. If this does happen, then the heater core will not be able to heat up and replacement will be necessary.

Within age and wear, there are 5 common ways in which electric auxiliary water pumps can fail:

• Weep hole is leaking coolant, indicating that the dynamic seal has failed. 
• The water pump leaking into the engine, making the oil milky and thin.
• Pump’s impeller fails and makes a chirping noise as it contacts the housing.
• The galleries in the water pump become plugged from sludge build-up.
• Electric motor fails due to a short in the wiring, making it inoperable.

Potential complications

A failed auxiliary water pump will almost never cause the vehicle to overheat. However, if inoperative, you might notice some of the following situations during driving:

• No warm air coming from the heater: since its primary job is to supply hot coolant to the heater core, the first symptom of a problem with this component would be no hot air blowing from the heater.
• Heater shows fluctuating heat: the temperature inside the vehicle is increasing or decreasing based on the driving mode, especially if there is a noticeable temperature decrease when the engine is idling.
• Windows defrost is not working: when windows fog up, the defrost mode is in charge of blowing warm air onto the windshield for clear vision. If the pump is failing, the windows will not defrost rather quickly.
• High-pitched buzzing sound: coming from under your dashboard, this might happen if there is an electrical short in the wiring, making the pump run faster than it should or continue to run after the engine is off.

How to replace an electric auxiliary water pump step by step

Once you have verified the condition of the electric auxiliary water pump and confirm its need for replacement, make sure to follow these steps one by one for an optimal replacement. Remember to always consider individual instructions proposed by the vehicle’s owner manual.  

Auxiliary water pump replacement step-by-step:

1. Drain the coolant from the system.
2. Remove any interfering parts, if necessary.
3. Disconnect the auxiliary water pump connector.
4. Remove all the hoses connected to the pump.
5. Remove all the mounting bolts and the auxiliary water pump.
6. Install the new auxiliary water pump and tighten the bolts.
7. Connect again the hoses back.
8. Install all previously removed parts in the reverse order.
9. Fill up the cooling system with indicated coolant to the required level.
10. Bleed coolant system according to the service manual.
11. Check coolant system for leaks.

And that’s it! You are done! 

Remember to always test drive the vehicle by driving it around and monitoring the cooling temperature!

Discover our range extension of Auxiliary Electric Water Pumps

The importance of proper selection of auxiliary electric water pumps

A good quality electric auxiliary water pump will determine the time span of an optimal coolant system and performance in any modern vehicle. These pumps are not only used to make modern engines efficient but have enabled the cooling of batteries in hybrid and electric vehicles.

With a complete range of auxiliary water pumps of more than 60 references, DOLZ offers its customers the best solutions thanks to personalized attention and the latest technology in the manufacture of water pumps for the aftermarket sector.

If you are looking for top-tier auxiliary electric water pumps, contact us and we will provide you with the information and support you need.

La entrada When and how to install an auxiliary electric water pump se publicó primero en Industrias Dolz.

Main uses and functions of secondary water pumps in vehicles

Secondary water pumps, also known as auxiliary pumps, are the star component in upsetting any vehicle’s cooling system. Even though not all vehicles have one (yet), these pumps are growingly popular as engines become more efficient and generate less excess heat. 

This type of pump is not connected to the main engine cooling system, so it is not running all the time. Instead, it provides supplementary coolant that circulates through a bypass hose to the heater core when needed. Additionally, it guarantees the cooling of the electric motor, and the inverter that electric and hybrid vehicles have.

Secondary water pumps keep the coolant flowing even when the engine is not running, ensuring there is always enough volume of coolant to keep the heater core warm. This enables vehicle engineers to use larger heater cores, allowing for the following features:

Improve driver comfort

Some types of engines, such as diesel-power ones, do not generate great amounts of heat when running or idling. This means that in lower engine speeds, the coolant in the heater core might lose its heat before being passed through the outlet. Adding a secondary coolant pump secures optimum heating even at low speeds.

This is important for passenger comfort, since it allows for sufficient heating even when passengers are driving in traffic or at low RPM. Moreover, an auxiliary water pump can also keep the cabin heated for short periods of time, even after the driver has turned off the ignition.

Maintain battery temperature

Thermal management poses a singular challenge in fully or partially battery-powered vehicles. Modern vehicles with hybrid drive and stop/start systems use batteries that must be kept at a certain operating temperature of engine to remain efficient in the long term. This is where auxiliary pumps come into play, for example to cool down the turbocharge.

The intelligent thermal management in these vehicles relies on several auxiliary pumps, which are turned on by the ECU when needed for a more targeted cooling. These pumps are individually adjustable; each of them is responsible for cooling a different area and can fail or be replaced without affecting the others.

Related content: When and how to install an auxiliary electric water pump

Signs and causes of failure in the secondary water pump

The main reasons why a secondary water pump fails are:

1. Fluctuating heating performance
2. Buzzing sound under the dashboard
3. Age and wear
4. Overheating
5. Low or bad coolant
6. Defective pump or improper installation

Keep reading to know more in depth about them:

1. Fluctuating heating performance

If the secondary water pump in a vehicle is inoperative, it will most probably lead to reduced or fluctuating heater performance at low speeds and at idle. This might also affect window fog, resulting in the defrost mode not working.

2. Buzzing sound under the dashboard

If there is an electrical problem with the secondary coolant pump, the pump might run faster than it should or continue to run after the engine is turned off. This will occasionally result in a high-pitched buzzing sound.

The sound indicates an electrical short in the wiring that powers the engine auxiliary water pump and is a key indicator of a need for replacement.

3. Age and wear

Like all moving and rotating components, brushes wear and windings short. The most common cause of water pump failure is simply from age and wear of its electric motor. Over time, most parts in a car or truck, auxiliary pumps included, start to break down due to constant wear and tear. 

4. Overheating

Overheating issues might affect any water pump’s lifespan. Too much heat in the engine can cause problems with the coolant system. Overheating can hasten the auxiliary water pump’s failure because increased cooling system pressures can force coolant past the shaft seals.

5. Low or bad coolant

Low coolant can cause a pump to fail. If too little coolant is circulating through the circuit, the blower fan will pull enough heat out of the coolant and cause the heater core to get cold. Furthermore, if the fluid in the cooling system is not properly maintained or if it is mixed with improper fluids such as water, corrosion will occur, reducing pump efficiency.

6. Defective pump or improper installation

A defective or improperly installed auxiliary pump will, at some early point, start showing the malfunctioning symptoms outlined in the previous section. Investing in a quality and compatible brand, as well as paying attention to all individual specifications of assembly will ensure the correct functioning of the vehicle’s cooling system.

You may like: Peculiarities of an auxiliary water pump

Guaranteed auxiliary water pumps with a trusted supplier

Industrias Dolz, with almost 90 years of history, is a leader in the manufacture of water pumps. From mechanical and electrical water pumps to variable and auxiliary water pumps.

Currently our range of auxiliary electric water pumps offers more than 70 references, all of them now available, which allows us to cover most of the current fleet of vehicles, fully covering the needs and demands of our customers and allows us to continue expanding our range of products.

This year we launched 28 new references of our auxiliary electric water pumps.

The new secondary water pump references cover the demands of more than 850 vehicle models from brands such as Mercedes-Benz, Audi, BMW, Ford, Porsche, Jaguar, or Opel.

If you want to know more about them, check this post!

And if you are looking for top-tier auxiliary electric water pumps, contact us and we will provide you with the information and support you need.

…yes we have!

La entrada Common causes and symptoms of secondary water pump failure se publicó primero en Industrias Dolz.

This article guides you through water pump leakage as a sign of engine malfunctioning, giving you all the necessary tips to prevent and react to water pump leakage and the resulting damage in the vehicle’s functioning and performance.

Water pump leaking: ¿What causes a water pump to leak?

1. Use of a wrong coolant liquid

A suitable coolant will be determined not only by the type of vehicle, but also by the climate and region where the vehicle is to be driven, thus, only the right coolant will fulfil its temperature-regulating mission.

Using the wrong refrigerant and/or mixing two different coolers can create solid residue in the circuit and cause leakage between the two contact faces of the dynamic seal. This will eventually lead to corrosive deposits that can generate clogging, cavitation damage and corrosion.

In order to choose the right coolant, it is essential to firmly consider expiry dates and follow vehicle manufacturer recommendations, as every individual engine is made of different materials and have specific needs.

2. Improper use of sealant paste

When learning how to install a water pump, remember that sealant paste is only necessary for models provided without a gasket. In such cases, be cautious, as using excessive sealant during the installation can damage the engine.

Applying the right amount of paste is crucial to avoid damaging the internal seal of the pump, as too much paste can create pollution in the system and damage the mechanical seal, resulting in water pump leakage and engine breakdown.

3. Inefficient water pump purging and/or dismantling

Never underestimate the degree to which a housing and a water pump impeller design contributes to its efficiency. Most of the wear that occurs on a water pump is on the internal parts of the unit. Experts must remove, inspect, and clean individually all auxiliary and core devices, to accurately check for wear at central parts and ensure an optimum operating condition.

Dolz’s recommended purging machine

Micrauto’s high-end technology machines eliminate at least 90% of residues in only 20-45 minutes. A highly efficient purging system that eradicates from iron oxide, to aluminum oxide and other oil residues that might cause leakage.

4. Lack of preventive maintenance

preventive maintenance should be always carried out by qualified professionals with the skills, experience and necessary tools to inspect, adjust, replace and repair any components that are not performing as intended.

Beyond this, specialists must advise end users to dig a little deeper into the condition of their water pump by carrying out routinary checks and considering best practices such as the replacement of the water pump and distribution system at the same time for a long-lasting vehicle service.

In these ways, preventive rather than corrective maintenance allows the solving of existing faults before these affect pump performances. The following offer some of the most evident and popular signs of water pump failure.

Related content: Keys to choose the best water pump company

Common signs of water pump failure

1. Coolant leaking

One of the first signs and most evident indications of a potentially faulty water pump is a puddle of colored coolant on the ground right under your parked vehicle. If the sealing of the pump cracks or breaks, the coolant will leak from the pump.

In this case, it is advisable to drive your vehicle immediately to your closest mechanic for repairing, as this can still mean a relatively easy and minor fix.

2. Engine overheating

A dying water pump cannot circulate coolant through your vehicle’s engine and, as a result, the engine will overheat. If the car temperature gauge is showing a temperature rise, it should be immediately taken to inspection.

The hotter the engine gets, the greater the chance of serious damage; including damage to the cylinders, pistons, head gasket and even resulting in engine breakdown. If you keep driving your vehicle, the damage might end up not being repairable.

Keep reading: How to detect cooling circuit problems

3. Appearance of rust and corrosion

Rust and corrosion on the water pump’s surfaces make the pump ineffective in moving the coolant. When checking your vehicle, you might spot rust or tiny holes on the exterior of the pump. If you do, it is time to replace the water pump, as a corroded or damaged one cannot operate effectively.

Yellowish and reddish coloring, white spots, incrustations and the presence of rust indicate the use of an unsuitable coolant and will eventually damage the dynamic seal, causing the pump to leak.

4. Whining noise

A high-pitched whining noise coming from the front of your vehicle’s engine when accelerating can be a sign that the water pump is failing. If the water pump components remain too loose or are worn out, the frontal part of the car will make a whining sound that some may describe as harmonic buzzing.

In many cases, the belt could be responsible for this sound. Having it replaced along with your vehicle’s maintenance schedule will keep you safe from more serious damage.

Water pump leaking: Preventions and solutions

Good quality water pumps do not leak under conditions of adequate work. Dolz’s water pumps, for instance, have its watertightness checked in a calibrated and extremely precise automatic leak detection machine. Therefore, it is important to ensure the following coolant conditions to avoid temporary leakage:

• Make sure there is no solid particles dissolved in the coolant that are smaller than 0,5mm.
• Make sure there is no air in the cooling circuit by constantly checking that the expansion vessel is within the minimum and maximum levels. Temporary pressure variations caused by air might cause a hydrostatic imbalance in the dynamic seal, causing a temporary leakage.

La entrada Water pump leaking: how to solve this problem se publicó primero en Industrias Dolz.

This popular water pump, suitable for the VAG group, applies to a wide range of applications. More than 14.5 million vehicles are in circulation throughout European roads with this reference.

One of the most popular applications that we find is the Volkswagen Golf D 1.6, 77kW that has been manufactured since 2012 until the present. With engine code CLHA, there are more than 142,000 registered vehicles.

What is the A255V Water Pump Solenoid?

If we look at the water pump, we see that it has an electric switch. But what is this connector? Is it a sensor? What is it for?

Many mechanics have doubts, some of them think that this cable is a temperature sensor, but this is not like this. It is a solenoid, or which is the same, an electromagnetic device that features electromagnetic linear actuation when subjected to an electric current.

To start with the basics, let’s review the vital components of a solenoid, which are a conductive, a coil of wire and ferromagnetic cylinder.

When electric current in the solenoid flows through the coil, a magnetic force is produced, and the plunger moves to the left.

Conversely, if no electricity flows through the coil, the plunger simply stays closed.

How does a solenoid work?

As seen in Figure 1 we see that when no electricity flows through the solenoid, the ball remains intact, keeping the circuit open (blue color) and allowing the coolant liquid through the conduit. On the contrary, in Figure 2 we can see that when electricity passes through the solenoid, the plunger pushes the ball to the left, closing the internal coolant circuit (red color).

Here is a more visual example of both situations:

• NO electricity by the solenoid.

The coolant circuit remains open because the solenoid does not block the circuit, giving the maximum flow depending on the engine speed.

• If current flows through the solenoid.

The magnetic field induces a force that pushes the ball, closes the internal coolant circuit and then generates a pressure and the shield will extend to cover the impeller. Which will result in the blockage in the coolant outlet of the water pump.

All this will make it easier for the engine to reach its optimal operating temperature faster.

What conclusions can we draw?

1.- The solenoid is not a sensor, in simple words, the solenoid is a device that converts electrical energy into mechanical work.

2.- If we connect the solenoid to a mechanical pump (not variable/switchable) it will not give any error in the control unit. If the electronic control unit gives an error from the water pump, it is because the solenoid is damaged, and it will have to be replaced.

3.- When replacing the water pump, if the existing solenoid works properly, we can use it to place it in the new water pump.

How to install solenoid in the water pump?

Wondering how to install a water pump with or without an impeller shield? Some mechanical versions of water pumps lack this shield, leading to questions about connecting the solenoid. Should you connect it or not?

What happens if we connect the solenoid to these pumps? Should we connect it or not?

Mechanically there is no problem. You can connect the solenoid without any issues, this won’t function. The mechanical pump will have the same maximum performance as a switchable design. However, we always recommend connecting the solenoid to the mechanical water pump to ensure the device doesn’t move around the engine and can be damaged.

To correctly install the solenoid, we first proceed to unscrew it and remove it from the old water pump. Then, as recommended by Industrias Dolz, it is screwed into the new one, regardless of whether the version is, variable or mechanical.

For further information on any of our product lines, receive commercial information or technical product specifications (including assembly notes), CLICK HERE.

La entrada DOLZ Answers: FAQ’s about the A255V water pump se publicó primero en Industrias Dolz.

Some water pumps, depending on the vehicle application, may or may not have a back housing. This component is independent of the water pump. Always located on the opposite side of the impeller, its main function is to house the thermostats and accurately regulate the coolant flow. The housing may be made of different materials, generally being plastic or aluminum, depending on the vehicle’s manufacturer.

These covers have a weep hole, just a few millimeters in diameter, whose function is to drain any coolant leakage that may occur due to a faulty seal. In addition, they serve as a connection point between the engine and the upper radiator hose.

Among its main benefits we find:

• Higher engine efficiency.
• Lower fuel consumption and decrease in CO2 emissions.
• Energy saving.

DOLZ range summary

Don’t miss it. Our range of water pumps with and without back housing suitable for Audi, Seat, Škoda & Volkswagen. All of them manufactured with an optimized design that ensure cooling at high RPM’s.

About our range, we highlight A282TM water pump, whose back housing is metallic which is more resistant to cracking and possible breakage.

Also noteworthy, A281 water pump with an auxiliary belt and a thermal management module integrated. This module enables the optimal operating temperature in a short period of time and with high precision.

The entire range is supplied with all components required for its correct assembly: water pump, gasket, cover anchor bolts, etc.

The complete range consists of: 

Related content: Dolz water pump: Maintenance tips and best practices.

Dolz, your safety choice.

DOLZ Water Pumps comply with all current regulations for adaptability and functionality regarding OEMs.

At Industrias Dolz we always recommend the replacement of all the elements that intervene in the distribution of the engine at the same time. Replacing the water pump and timing belt will improve the performance of this operation in both quality and safety. The fact is, by performing the replacement at the same time, the parts are better coupled to each other from the beginning and the water pump bearings do not weaken so easily.

Get in contact for more information.

…yes we have!

La entrada Water pumps with & without Back Housing se publicó primero en Industrias Dolz.

Unlike traditional water pumps that constantly circulate the coolant, variable water pumps do not run all the time, but supply the coolant only according to current needs.

As we could see in previous posts, water pumps play an essential role in the proper functioning of the engine. Therefore, the optimization in the cooling system with the efficiency in the consumption and emissions of the vehicle mean that more and more vehicles incorporate this type of switchable pumps.

Variable water pump operation

As its name suggests, this type of water pump can be variably controlled. In other words, they only circulate coolant when needed. In this way, the time to reach the optimum temperature of the engine is shortened thanks to the variable performance of the pump, which helps to warm up the engine more quickly when the engine starts cold.

The mechanism that operates this variability function of the water pump is a magnetic valve, connected to the body of the water pump, which adapts the capacity of the flow rate to the different operating conditions of the engine. The engine control unit enables or disables this function.

An example is our part number A255V, which has a ring around the impeller, which receives the order from the vehicle’s control unit to go up or down, allowing the impeller to run or not the coolant.

The component to transmit orders to the water pump is the electric actuator, it is mistakenly thought to be a temperature sensor, but all it does is transmit the order to raise or low the ring that surrounds the impeller.

Depending on the water pump model, variable water pumps can be connected with a cable or a molded connector (solenoid valves).

This variable system guarantees the proper operating conditions of the engine block. When the variable water pump is “on”, the flow of the coolant circulates unhindered to the cooling circuit. On the other hand, when its state is “off” it causes the magnetic valve to activate and therefore the impeller can not move the coolant.

Among the advantages of the variable water pump, we find:

• Ability to manage water pump speed through controls without compromising required cooling.
• Overall better vehicle performance.
• Reduction of the CO2 emission that is emitted into the atmosphere thanks to the generation of a variable flow.
• Reduction of fuel consumption.

Keep reading: Types of automotive water pumps

Know more about Dolz’s variable water pump

Dolz offers mechanical, auxiliary, electrical and variable water pumps for more than 97% of the European vehicle fleet.

Its range of variable pumps currently totalize more than 10 PN’s, both for Tourism and Industrial Vehicle.

These variable water pumps are designed with the latest technology for the highest efficiency. For this reason, Dolz variable water pumps can be divided into two different types:

1. Variable water pump with PSF technology (Pneumatically Switched Flow – digital control for mechanically driven pumps). This system allows that, through a vacuum system, the water pump varies in flow depending on the different needs required by the engine.
2. Variable water pump with ECF technology (Electro-hydraulically Controlled Flow. Water pump can regulate the flow rate in between with a modulated hydraulic pressure). This system is based on the on/off principle able to control continuous flow.

All of them have 100% cast aluminum material, resistant to wear and OE equivalent, always following the highest standards.

Dolz, an expert manufacturer of water pumps since 1934.

La entrada Switchable / Variable water pump: All you need to know se publicó primero en Industrias Dolz.