Coolant Expansion Tanks
Coolant reservoir bottle replacements
Is your coolant expansion tank failing? Get in touch with a radiator technician for a replacement quote.
Is your coolant expansion tank failing? Get in touch with a radiator technician for a replacement quote.
Coolant reservoir tanks can become discoloured, brittle, contaminated with sludge or even break with wear and tear damage. A damaged coolant expansion tank needs to be replaced immediately to ensure the effectiveness of your vehicle’s cooling system.
The coolant expansion tank captures escaping coolant when the temperature and pressure in the radiator rises. Coolant will then return to the radiator when the temperature decreases. The vehicle cooling system can fail if a damaged expansion bottle is not replaced.

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A qualified technician can correctly install a coolant expansion tank
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Australia's largest network of vehicle cooling specialist workshops
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The largest range of OE and aftermarket radiator parts in Australia

National warranty supported by our network of radiator workshops
COB003
Suitable for: Ford Falcon BA/BF, Territory SX/SY/SZ
COB014
Suitable for: Volkswagen Golf, Beetle, Audi A3, and Skoda Octavia
COB021
Suitable for: Supercharged Engines for Holden Commodore VT-VZ, Statesman WH/WK/WL, and Monaro V2
COB037
Suitable for: Nissan Patrol GU and Ford Maverick Y60
COB038
Suitable for: Hyundai Elantra XD and Tiburon
Modern vehicle cooling systems are highly pressurised to ensure efficient thermal management. As the engine coolant heats up, it expands, creating pressure inside the radiator.
The coolant expansion tank holds coolant lost as the pressure rises, returning it to the radiator when the temperature and pressure drop. The coolant expansion tanks supplied by Natrad ensure that the pressure within the radiator is controlled, and engine coolant is not lost during expansion.
As well as coolant expansion tanks, Natrad supply a wide range of cooling system parts and accessories for replacement and performance upgrade. When you replace the coolant expansion tank, you may need other parts and fittings. That's why Natrad stock a large range of radiator caps, hoses, fittings, fans, water pumps, and any other vehicle cooling parts.
Ask your local Natrad technician about a free cooling system inspection to see which parts need replacing.
Find the right coolant expansion tank for your vehicle by using our fitment guide that includes a wide range of popular makes and models.

Enter your postcode below to locate the Natrad store near you.
Get more value when you nip into Natrad. We’re offering 15% off the cost of parts for your first service as thanks for choosing us. T&Cs apply.
If you have a basic mechanical knowledge, installing a new coolant expansion tank is a fairly straightforward procedure. However, you need to be aware that many newer trucks, cars and SUVs require priming the coolant system according to the manufacturer’s instructions to prevent bubbles or air pockets forming.
A Natrad technician can help you select a replacement coolant expansion tank for your vehicle with the correct fittings, and they can install the new tank for you if required.
Signs that a coolant expansion tank needs to be replaced include:
Prompt replacement of a faulty coolant expansion tank will save potentially expensive consequences of engine overheating. A Natrad technician can diagnose the source of the cooling problem and recommend the best solution.
The coolant reservoir tank should never be totally full. Check the coolant level when the vehicle is cold. If the coolant level sits between the maximum and minimum level marks, there’s no need to add further coolant. If the coolant level is below the minimum level, top up the coolant using a mixture of the correct coolant for your vehicle and distilled water.
A Natrad specialist can help you to find the right coolant for your vehicle. If you think you have a coolant leak, have your vehicle checked by a technician to determine the cause of the leak.
If the coolant level is just a bit too high, the excess will be gradually lost through evaporation. If the coolant expansion reservoir tank is very over-full, it will overflow through the reservoir overflow tube when the engine heats up. Once the level drops enough, it will still be high but will no longer overflow.
If you do notice that the coolant expansion tank overflows after being overfilled, check the coolant level again once the car has cooled to make sure that the coolant level hasn’t dropped too low.
Do you have a leak in your cooling system? Ask a specialist about the right replacement cooling expansion bottle for your car.
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