An Overview of Switchable Water Pumps

You must choose between a switchable and a non-switchable water pump if you require one for your modern diesel. The benefits and drawbacks of each water pump option will be discussed.

Switchable Water Pump: What Does That Mean?

A water pump that can modify the amount of coolant it pumps by some form of mechanical function is referred to as a switchable pump.

Why are there Switchable Water Pumps?

Water pumps cannot change their pumping volume for any reason other than RPMs since they are locked to spin at the same speed as the engine. This means that regardless of engine temperature, the water pump will pump the same volume of coolant. Whether the engine is hot or cold, the water pump performs the same amount of effort.

This certainly isn't ideal because the engine will take longer to achieve operating temperature if coolant is pumped. Engine efficiency will suffer and emissions will rise when it is operating below operating temperature. An focus was made on accelerating the temperature of engines as government officials started enforcing harsher pollution standards.

The Function of Switchable Water Pumps

There are many different types of switchable water pumps, but the most typical one has a mechanism that moves to stop the water pump impeller from moving coolant. This usually takes the form of a shield or shroud that will cover the pump and stop coolant from flowing through it. The shield retracts if additional coolant flow is needed. On the other hand, the shield will extend to cover the impeller if coolant flow needs to be limited. Depending on the designated coolant flow, certain water pump designs will move the pump impeller instead, with the impeller going in and out.

Switchable pumps are distinguished by a shield into which the impeller can retract.

How Do Switchable Water Pumps Operate?

Moving shield design for a Volkswagen TDI

Did TDIs ship from the factory with a switchable water pump?

2015 TDI vehicles with the EA288 engine code came equipped with a switchable water pump out of the box.

Water pump for the 2015 TDI, exploded view

I have an EA288 2015 TDI. Can I use a non-switchable pump in it?

In our tests, there were no problems with using a non-switchable pump in a 2015 TDI. The maximum performance of a switchable design and a non-switchable pump will be equal, therefore overheating is never an issue.

• Switchable Water Pump EA288
• Non-Switchable Water Pump EA288

Switchable water pumps were they used in Mercedes Sprinter vans?

The switchable pump in Sprinter vans powered by the OM651 2.0L 4-Cylinder engine is vacuum-operated. Yet, issues have arisen because of the switchable design. The water pump switching mechanism in these engines is susceptible to malfunction, allowing coolant to enter the vacuum system. Problems with drivability may result from this. See Sprinter 4-Cylinder OM651 Losing Coolant, Limp Home Mode for further information on this issue.

I have a Sprinter Vehicle. Can I use a Non-Switchable Pump in it?

Use Switchable Water Pumps in the Mercedes GLK, ML, GLE, or E-Class Bluetec?

Yes, all OM651 4-cylinder Bluetec cars, including the GLK250, E250, ML250, and GLE300d models, have a switchable pump.

In my GLK, ML, GLE, or E-Class Bluetec, may I use a non-switchable pump?

Using a non-switchable pump is not problematic mechanically. The check-engine light may be activated for a thermostat or water pump warning if the engine programming detects a delay in engine warm-up time. If the ECU isn't reprogrammed, there might be a light in the van's instrument cluster, which could prevent the vehicle from passing inspection. Thus, it is not advised to install a non-switchable pump in a Mercedes vehicle.