Your cooling system plays a critical role in your vehicle’s performance and efficiency. Internal combustion engines are designed to run at maximum efficiency within a narrow temperature range. Outside this range, the engine will use more fuel, or run poorly, and overall engine reliability and longevity will be reduced. If your cooling system fails altogether, the engine will overheat, which could cause head gasket failure, and damage to bearings and pistons. The cooling system is vital.

Your Subaru engine is kept at the correct operating temperature by liquid coolant pumped through internal galleries in the engine block and heads.

Heat from the internal combustion process is transferred from the engine to the coolant. The coolant then passes through a radiator which transfers the engine heat into ambient air passing through the core. The system is efficient enough so that even with ambient temperatures past 50 Celsius, the engine can still run too cool if the flow of coolant ("flow" deleted) is not regulated and the temperature controlled. This is done by two parts of the cooling system: the thermostat, and the electric cooling fan controlled by a thermostatic switch.

When engine temperature gets too low, the thermostatic switch cuts power to the fan and the thermostat closes off the flow of coolant from the radiator to the engine. As the engine gets hotter, the thermostat opens to allow hot coolant to flow though the radiator. If the temperature rises too far, the thermostatic switch turns on the fan to increase the flow of air through the radiator. This system keeps the temperature so constant that the driver will not see the temperature gauge move once the engine reaches operating temperature.

At All Drive Subaroo we are aware of the importance of keeping your car cool under the bonnet, and we routinely check for leaks or other problems with your head gasket, hoses or radiator. Most of the times any fixes required are easy and simple but some are more complex. We recommend regular inspections for leaks around the Subaru heads.

"All Drive Subaroo are Subaru cooling systems experts. When it comes to your radiator, or any other part of your car’scooling system, we are the people to see. Phone us anytime on 02 9915 9900 or 0420 319 049 for expert advice "

The Subaru Cooling System Comprises the Following Parts:

Water pump



Thermostatic switch

Electric cooling fan

Various rubber hoses

Drive belt

Cabin heater core and fan

Radiator caps on header and radiator

Overflow tank

Remote header tank

Head Gaskets

We have all these components in stock and ready to go. Visit our Online Parts Store

Difficulty of Subaru engine overheating diagnosis


Given the complexity of the cooling system, problems with maintaining correct engine temperature or with retaining coolant, might have a number of causes and diagnosis can be tricky. Many customers have come to us with what they think is a head gasket problem, and are greatly relieved when it proves to be a problem with other parts of the cooling system. When you bring your car to All Drive Subaroo, our technicians thoroughly inspect the engine compartment and cooling system to determine what work or service is required. Checks that we are able to perform include:

  • Power vacuum bleed of system
  • TK check
  • Engine compression test
  • Cooling system pressure test
  • Fluid dye test
  • Cylinders speed test
  • Electrical diagnosis using Subaru SSM machine

One very common problem occurs when cooling systems are fully drained and then refilled, either as part of a routine service replacement of coolant, or following cooling system or head gasket repairs where the coolant is drained. Modern Subarus cannot simply be filled up with coolant from the header tank or directly into the radiator. If this is done there will be large pockets of air left in the system, and the engine will overheat. There is no bleed nipple on Subaru engines to ensure that all air is out of the system, and the only way to do this properly is by use of a special coolant vacuum purge and refill kit that sucks air out at one end, while drawing coolant in at the other. Not all workshops have this equipment available, but as a specialist Subaru service center, ADS does, as well as all other specialist tools and equipment required to service Subaru cars. Whatever the problem is, we can most likely fix it for you on the spot.

Genuine Subaru Radiators vs knock-offs


A few decades ago, car radiators were made from brass and copper, highly durable materials, and easy to repair. There used to be a thriving business in reconditioned radiators, and radiator repairs such as re-braised or soldered tanks, and flushed and cleaned cores. Modern cars however use much thinner aluminium cores and plastic tanks. When these fail they often cannot be repaired. This has created a new market for replacement radiators, and after-market manufacturers, notably Chinese companies, have been quick to jump in. The Chinese built after-market replacements are less than half the price, but they are virtually non-serviceable. They are a copy of the OEM Subaru design, but the build quality is inconsistent. We have tried to install units supplied by customers, only to find that the mounting points do not precisely align, or the unit is slightly too wide for the mounting frame, requiring a little distortion to fit. We have observed that these radiators inevitably fail after only a short time, and in demanding conditions, simply fail to keep the engine cool. This is because they use less metal—one or two rows of honeycomb cooling cells instead of three, as in the OEM Subaru and high quality Japanese made after-market units. The Chinese units also use inferior seals to hold the top and bottom tanks on, and generally thinner gauge materials all round. The result, all too often, is overheating and an expensive engine repair that could have been avoided. OEM Subaru radiators, and other quality units built in Japan, are not cheap, but they are of very high quality. We keep a large stock of OEM Subaru radiators, and high quality Japanese built after market units in stock, and we are very aware of the importance of making sure your car engine stays cool and in optimum condition. Ensuring your car engine runs at the correct temperature, may involve a radiator fluid exchange, a simple part replacement or more complex repairs.

Cooling System Services we Offer

ADS can take care of all your cooling system needs, from routine services, such as flush and replace coolant or renew belts and hoses, to trouble shooting and repair of radiator, or water pump, heater core, or cooling fans. If your problems prove to be related to the head gaskets, or other major engine components, we are fully equipped to deal with head gasket, engine or cylinders head replacements or repairs quickly and efficiently. We use and recommend Subaru antifreeze replacement at set mileage or time intervals. To prevent expensive, recurring problems, the integrity of the entire cooling system should be inspected and tested when a head gasket is replaced.


If you are having problems with your cooling system, and are not sure if the head gaskets are involved, check our comprehensive head gasket page for all the information you need.

enquire or book an appointment now

For further information use our convenient online enquiry form, and one of our specialised technician will call you to discuss your enquiry. Remember, the more specific details you can provide, the more accurate our assessment will be. Alternatively, call us any time in business hours and talk to Niazi on (02) 9915-9900 or 0420 319 049.

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If you're good with tools and want to replace the Subaru air compressor or evaporator kit yourself then we can supply you with all the necessary Subaru air conditioning parts, compressors, TX valves, evaporators and hoses. Our Subaru parts online website also offers a comprehensive range of new, pre-loved and reconditioned Subaru parts sourced locally and internationally. Our skilled technical staff will match you to the best part, at the best price. We will also provide technical advice and assistance in the installation of your parts.

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