Engines produce a lot of heat; temperatures inside the combustion chamber reach thousands of degrees. Without coolant – and the cooling system – your vehicle would quickly overheat. That’s why it’s important to maintain your car through regular coolant flushes or exchanges.
Coolant, otherwise known as anti-freeze, is a specially-formulated fluid that dissipates heat to provide the desired engine operating temperature. All coolant is combined with water (typically a 50/50 ratio) before being put to use inside an engine. Three primary ingredients make up the mixture:
- Water: serves as the primary heat transfer mechanism in coolant.
- Glycol: glycol provides anti-freeze properties that prevent the water from freezing in cold temperatures.
- Corrosion inhibitors: a corrosion inhibitor package is added to prevent erosion and rust that would otherwise occur in the cooling system. Coolants are classified based on the type of inhibitors (also called additives) they contain.
Other ingredients, such as anti-foaming agents and trace dye, are also added to the coolant in small quantities.
What’s the Cost of a Coolant Flush Service?
The price of a coolant exchange depends upon which of the two services , drill-and-drain or flush, is performed. Typically, a flush costs more. Cost will also vary depending on where the service takes place; the dealer often charges more than an independent shop.
Some repair facilities offer additional services, such as pressure testing to check for leaks, to compliment the coolant exchange. Others include coolant flushing along with oil and brake fluid changes as part of a maintenance package.
Different vehicles require distinct types of coolant. The kind your car takes, and the brand the shop selects, will also affect the price.
Given all the variables mentioned above, the cost of a coolant flush ranges between $75 and $190. That figure is the total amount, including both supplies and labor. Coolant costs on average around $30 for a bottle.
Flushing out a cooling system is largely a standard process. But the type of vehicle can also play a role in either increasing or decreasing the price. Here are the estimated price ranges for several cars of different years, makes, and models:
|2014 Volkswagen Jetta||$163|
|2012 Dodge Grand Caravan||$149|
|2007 Nissan Pathfinder||$147|
|2013 Mini Cooper Paceman||$157|
|2005 Cadillac Escalade ESV||$143|
|2008 Audi S8||$163|
You can get your coolant flushed at almost any repair shop – from the dealership to a local-owned facility.
Cooling System Operation
Coolant must travel through the engine and cooling system to do its job. A typical cooling system contains these primary components:
- Cooling fan (s)
- Heater core
- Overflow tank
- Passages inside the engine
- Radiator cap
- Water pump
Coolant’s journey begins when the vehicle is running and the mixture is drawn from the radiator by the water pump. The fluid then flows through passages in the engine block and cylinder head.
From there, the route depends on whether the thermostat – a device used to control engine temperature – is open or closed. If the thermostat is closed, coolant is prevented from circulating back to the radiator until the engine warms up. On the other hand, if the vehicle is at operating temperature (usually around 195 degrees), the thermostat will be open and coolant will be allowed to flow back to the radiator.
The radiator is a heat exchanger: air passed across its fins remove heat from the coolant and dissipates it into the atmosphere. It’s as the vehicle is traveling down the road, and air is pushed through its grille, that this process takes place. When the car is stationary, a supplemental cooling fan blows air across the radiator to keep things cool.
A greater difference in temperature between the coolant and outside air results in more effective heat exchange. For this reason, the radiator is pressured to increase the boiling point of the coolant within.
The radiator cap contains a pressure valve that increases cooling system pressure to a certain level. When the desired pressure is reached, the cap seal unsets and coolant flows into the recovery tank. The cap also contains a vacuum valve that opens to allow coolant back into the radiator when the engine is off.
When coolant is circulating through the system, it also flows through a mini-radiator called a heater core. When the driver turns the heater on, the blower motor propels air across the heater core and into the cabin to keep things warm.
Hoses connect many parts of the cooling system. Primary applications include the large-diameter upper and lower radiator hoses, which connect the radiator to the engine, and the heater hoses used to connect the heater core to the engine. There’s also a bypass hose used to route coolant back to the engine when the thermostat is closed.
Why Is a Coolant Flush Necessary?
Over time, corrosion inhibitors in the coolant deteriorate and the formula becomes acidic. The mixture then begins to eat away at vital engine components. Debris accumulates in the cooling system, turns to sludge and causes obstructions. The eventual outcome is overheating and extensive engine damage.
A coolant flush counteracts corrosion by cleaning out contaminants, while also replenishing vital corrosion inhibitors. The old mixture is either drained or flushed out with a dedicated machine. Then, brand new coolant – with fresh inhibitors – is added in.
How Often Does A Coolant Flush Need to Be Done?
How often a coolant flush should be performed depends on the type of vehicle. Many older engines use traditional green coolant with inorganic additives. Generally, with these applications, service should be conducted every 30,000 miles or so.
New cars, which usually use organic additive coolant or a hybrid (mix of inorganic and organic additives), can generally go over 100,000 miles. Such mixtures are referred to as long-life or extended-life formulas.
You can find the exact interval for your vehicle by consulting the manufacturer maintenance schedule outlined in the owner’s manual.
Should You Go For a Coolant Drain-and-fill?
As was mentioned earlier, there are two types of professional coolant exchanges: a drain-and-fill and a flush. Often, both are referred to as a “flush”, although they are two distinct procedures:
- Drain-and-fill: a technician drains the old coolant, typically through either the drain petcock or lower radiator hose, then closes the system and refills it with fresh coolant. Air must be bled from the system afterward.
- Flush: usually a dedicated flush machine is hooked up to the cooling system; old coolant is removed then new is added. Air is purged from the system at the same time.