What does the radiator overflow tank do?

The radiator overflow tank is an important component that prevents the overflow of engine coolant. It is connected to your radiator and houses excess coolant until it has reached a low temperature again.

Coolant keeps your engine at a healthy temperature and travels between the radiator and the engine. When the coolant is heated by the engine, it expands, causing it to take up more space. The overflow tank collects the expanded coolant, preventing overflow out of the engine cooling / radiator system. Once the coolant is at a suitable temperature (cooled down), it is let back into the radiator.

More info on how the overflow tank works >


Symptoms of a damaged radiator overflow tank:

Coolant leaks – You may notice that coolant is appearing under your vehicle. This can be caused by a crack in your overflow tank, radiator, or hoses. Coolant leaks should be fixed immediately before they cause damage to your engine.

Coolant leak fixes in Hamilton >

Overheating – The radiator overflow tank plays a vital role in maintaining the coolant level within the cooling system. If the tank is damaged and coolant is leaking or not properly replenishing the radiator, it can lead to an insufficient coolant supply. This can cause the engine to overheat, which may be indicated by a rising temperature gauge on the dashboard or the appearance of warning lights.

Physical damage to tank – Physically inspect the radiator overflow tank for any visible signs of damage, such as cracks, bulges, or leaks. A damaged tank may appear distorted, discolored, or show other signs of wear and tear.


What causes a damaged radiator overflow tank?

  • Age and wear: Over time, the plastic or composite material used to construct the radiator overflow tank can deteriorate due to exposure to heat, pressure, and chemicals in the coolant. With age, the tank may become brittle, leading to cracks or leaks.
  • Impact or physical damage: Accidents, collisions, or even rough handling during repairs or maintenance can cause damage to the radiator overflow tank. Any direct impact or forceful contact can result in cracks, fractures, or other forms of damage.
  • Excessive pressure: The cooling system operates under pressure to raise the boiling point of the coolant. However, if the pressure in the system becomes too high due to a malfunctioning radiator cap, a faulty pressure release valve, or other issues, it can place excessive stress on the radiator overflow tank. This can lead to deformation, leaks, or even rupture.


How important is an overflow tank replacement?

It is important that all parts of your cooling system function as they should. This is because your cooling system plays the vital role of keeping your engine at a suitable temperature. When an engine overheats, parts will bend, warp, seize and stop working, often meaning that the engine will need to be replaced. 

If you notice a problem with your overflow tank, we recommend that you have the tank replaced as soon as possible to avoid serious engine damage. 

Radiator Overflow Tank Inspection & Replacement in Hamilton

At Grimmer Motors, we can replace your vehicle’s overflow tank. Our skilled mechanics are quick to diagnose and fix errors in your car’s cooling system. This allows for your car to be on the road again sooner rather than later. 

Whether its the overflow tank, the radiator, thermostat or water pump, we can provide high-quality cooling system new parts and replacements in Hamilton. To get your car fixed, contact us today!

Please Note – we don’t generally stock or supply just “parts only” for this service. We are a general automotive repair workshop. If you are able to bring your vehicle to us, we can diagnose the problem, find and fit the necessary parts, or organise the appropriate service for you.


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