Do you want to cool down? Not Cooling?　Radiator leak tester to determine the condition of the engine cooling system

The cooling system, including the radiator, is the key to maintaining the performance of a water-cooled engine. The cooling system, including the reservoir tank, is all in a closed system, and there is no mechanism for long-life coolant to drain out of the car body like the overflow pipe of a carburetor. Nevertheless, when there is a sweet smell peculiar to LLC coming from somewhere, a radiator leak tester may be able to pursue the cause.

Water-cooled engines are also useful in promoting warm-up operation in winter

The cooling system of a water-cooled engine has an important role to play not only in summer but also in the cold winter months. In the case of injection vehicles, the mixture is thickened by temperature compensation to cope with the winter months when gasoline is difficult to atomize, but at the same time, coolant is utilized as a heat source until the thermostat in the cooling path is opened. The same applies to carburetor cars; some 1990s models were equipped with carburetor heaters that passed coolant through the outside of the float chamber to accelerate warming up. The coolant circulating inside the engine removes heat from the cylinder head, which is the hottest part of the engine, is cooled by the running wind as it passes through the radiator, and is pumped back into the engine by the water pump, repeating the cycle. In addition to the earlier example of promoting warm-up immediately after start-up, cooling water during driving is also designed to maintain a certain temperature range, not just to cool it down.

Why does it leak when the water temperature rises while it does not leak at room temperature?

The radiator cap is important for this purpose. Water boils at 100°C under atmospheric pressure, and the boiling point decreases as pressure decreases; conversely, the boiling point increases under high pressure. Radiator caps work to keep water from boiling at 100°C by adding pressure within the cooling system, which rises as the coolant temperature rises. For example, if the cap body has the number 1.1 written on it, the valve opens at 1.1 kg/㎠ (approx. 107 kPa) of pressure in the cooling path. When the cooling system is pressurized to 107 kPa, the boiling point of the cooling water rises to approximately 120°C, making it harder to boil and harder to overheat than under atmospheric pressure. However, when the pressure inside the cooling system is higher than atmospheric pressure, the possibility of coolant leakage problems increases. While there is no need to worry about this in a new car, in an old car or an out-of-print car, where deterioration of rubber, plastic, and metal parts is a concern over time, coolant may seep or leak from joints of various parts. This will cause the pressure in the cooling system to drop, and if the drop in pressure causes the coolant to boil and air bubbles to form around the water pump, there is a risk of stagnation of circulation, which can lead to overheating. If the sweet smell of long-life coolant is not noticeable at room temperature, but when the water temperature rises during driving, the sweet smell of long-life coolant wafts through the air, you should suspect that coolant may be leaking from somewhere.

Radiator leak tester that forcibly pressurizes the cooling system.

Radiator leak testers are useful for detecting coolant leaks that occur while driving. By attaching the end of a pump with a gauge to the radiator and pressurizing it, the entire cooling system can be pressurized to reproduce running conditions. While an air blow gun connected to an air compressor can be used to apply pressure from the cap, the advantage of a dedicated tool is that the pressure to be applied can be monitored. The engine cooling system remains airtight even at pressures higher than atmospheric pressure, but this does not mean that the pressure can be increased to any extent. Excessive pressurization can cause gaskets and O-rings to come loose. This tester is specialized for radiator inspections and can check pressures up to 2.5 bar (200 kPa) with a guideline. For the cap with the 1.1 kg/㎠ setting mentioned above, you would only need to pressurize it to 0.98 bar to check for leaks. The fact that the gauge shown here has a green band in the area below 1 bar is probably in response to the general 1.1 kg/㎠ setting. When pressurizing with the tester's pump via the radiator cap adapter, it is important to make sure that the setting limit for each vehicle is not exceeded and that the pressurized state can be sustained further. If the pump pressurization does not raise the pressure to 1 bar, there is definitely a coolant leak somewhere in the cooling system. Leaks can occur in a wide variety of places, including the radiator itself, hoses, water pump mechanical seals, thermostat case, etc. In addition, there is the possibility of leaks from the cylinder head gasket into the combustion chamber or oil lubrication path. If the leak is inside the engine, a sweet smell will be mixed with the exhaust gas if it is in the combustion chamber, and if mixed with oil, the oil visible through the engine oil inspection window will be emulsified. On the other hand, if the pressure rises to 1 bar at one time and then slowly decreases, the leak is minor and if the bike is running, the heat from the engine may be evaporating from the side of the leak. In such a situation, you can realize the benefits of a radiator leak tester, which allows you to closely observe the leak while the bike is stopped.

Surprisingly common radiator cap defects can also be determined.

Besides water leaks, another problem that tends to occur in the cooling system is a defective radiator cap. The radiator cap pressurizes the cooling system to raise the boiling point and at the same time serves as a safety valve that allows coolant to escape into the reservoir tank in the event of excessive pressure buildup. This safety valve has a simple structure that combines a rubber seal and a metal spring that adheres closely to the radiator mouthpiece. If the airtightness deteriorates due to aging deterioration, including hardening of the rubber, or foreign objects becoming entrapped, the pressure cannot be maintained and bubbles may be generated due to a drop in boiling point, resulting in the risk of overheating conditions. This is the same logic as water boiling at 100°C under atmospheric pressure of 1000 hPa boiling at 87°C at 630 hPa at the summit of Mt. Therefore, radiator caps should definitely be replaced periodically as a consumable item, but if you have a radiator leak tester, you can check whether or not the pressure can be maintained without leaking to the value indicated on the cap. Normally, we don't worry about air-cooling or water-cooling, but when a leak starts, we have to be aware of it even if we don't want to be. Leaking cooling water can cause overheating and other serious problems, so it is necessary to identify the cause of the leak and perform appropriate maintenance as soon as possible. In this case, you will find the radiator leak tester, which can keep the cooling system pressurized, useful.

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