What are the water pump and thermostat?

The water pump and thermostat are two of the most crucial components of your engine. The pump’s purpose is to circulate coolant throughout the engine to draw heat away from the combustion chamber and send it to the radiator where it can cool down. Without this feature, the engine will overheat and fail. The thermostat opens and closes are certain points to change the volume of coolant flowing through the engine so that it will operate in a specified temperature range. Water pump and thermostat failures can leave you and your car stranded on the side of the road so it is important that if there are any symptoms present that it be addressed quickly so you can carry on driving your vehicle with confidence.

There are a couple of basic water pump designs that manufacturers use. The first is a mechanical design. The water pump has an impeller that is connected to a pulley and driven by the serpentine belt. The second is an electric design where the impeller is driven by an electric motor. Most modern engines use the electric design and most are advanced enough that the car’s computer can control speed and even let it run after the car is turned off. This allows the pump to only use as much power as is needed at any given time and reduces the parasitic draw on the engine, freeing up some HP.

How do they fail?

One common failure of both designs is the simple leak. Sometimes the seals on the bearings or housings will fail and coolant will leak out. On the older mechanical pumps, the impeller or bearing itself can fail preventing the pump from circulating coolant. With the electric pumps, most times the electric drive will slow or fail completely. Regular inspections can find the electronic clues as to when this is happening and can give you advanced notice of impending failure. Most newer vehicles are equipped with a safety feature called “limp mode” where as the vehicle detects a failure of a water pump, it will only allow enough movement to get the vehicle and you safely off the road. Most of the time, this prevents the engine from overheating and therefore saves you the thousands of dollars it would cost for a new engine. The older mechanical pumps usually do not have this feature so minding the coolant gauge on your instrument cluster is important so the you can turn the car off as soon as a problem is indicated.

Most of the time, RRT will recommend replacing the thermostat at the same time as the water pump. In almost every case, the thermostat is located adjacent to the water pump and needs to be removed to access it. This saves you labor as you usually only would need to purchase the part during this job. A thermostat is also essential to a properly running engine and it’s simple design is also it’s downfall because it can become gummed up or jammed. This creates a blockage in the coolant system preventing heating from being removed properly form the engine or by not allowing the engine to reach proper operating temperature, depending on if the thermostat fails in the open or closed position.

Are there any upgrades?

The short answer is yes, there are upgrades when it comes to the water pump and thermostat. But they are not always recommended for street cars. On track or race cars, the operating requirements of an engine are vastly different from how they were originally designed and therefore upgrading makes sense. However on a street driven vehicle, running more coolant volume or a lower temperature thermostat does not always benefit the vehicle. Please consult with the experts at RRT to determine if you should upgrade beyond the OEM parts or if simply replacing the factory parts with new units makes more sense.