When was the last time you traded??Water-cooled engine coolant should be checked before summer arrives.

The function of the coolant is important for the water-cooled engine that absorbs the heat generated in each part of the engine and dissipates it from the radiator. The coolant is called "long-life coolant" because it can be used for a long time, but it does not mean that it should be replaced without replacement. It is important to replace the coolant before it degrades and causes damage to the inside of the engine.

Coolant has the ability to prevent freezing and rusting of metal parts

The coolant drain bolt is often located at the lowest point of the cooling system. In the case of the Kawasaki GPX250R, it is located on the water pump cover on the left side of the engine. Some models have the drain bolt on the radiator pipe. Rusty iron pipes leading to the water pump are evidence of age and deterioration.

Rubber hoses don't rust, but iron pipes gradually corrode. Even if long-life coolant is used correctly, it can rust, so models that have used only tap water for many years may be doomed.

In contrast to air-cooled engines, which rely on running air, the greatest feature of water-cooled engines is that the temperature can be controlled by the cooling liquid. Water-cooling is essential not only for large-displacement, high-power engines, but also for reducing the warm-up time when the engine is cold, even for moped scooters, in order to reduce emissions. Coolant pumped by the water pump circulates through the engine's internal cooling channels and the radiator, and depending on the water temperature, a thermostat built into the pump automatically determines whether the coolant circulates only through the engine or also through the radiator.

A special long-life coolant is used for the coolant that absorbs the heat generated by the engine and dissipates it into the air through the fins of the radiator. The main ingredient of the coolant is ethylene glycol, a type of alcohol, and tap water begins to freezeAchieves both freezing point depression (no freezing at 0°C) and boiling point rise (no boiling at 100°C)Role. Since the cooling system of the engine is basically closed, it is most important to lower the freezing temperature because if the coolant freezes and expands in volume during the winter, it can cause serious problems inside the engine. At the same time, it is also necessary to raise the boiling point because if it boils at 100℃, it will evaporate and the volume will decrease. The boiling point is raised by raising the pressure of the entire cooling system above atmospheric pressure with the radiator cap, but at the same time, the high temperature durability is improved by the ability of the coolant itself.

furthermoreThe coolant also contains rust inhibitors to prevent rust from forming inside the engine, and defoamers to reduce the foam that is generated when the water pump impeller pumps the coolant.In contrast to the aluminum alloy crankcase and cylinder head, the cooling pipes on the outside of the engine are often made of iron. In contrast to the aluminum alloy crankcase and cylinder head, the cooling pipes on the outside of the engine of commercial vehicles are often made of iron-based materials, and if tap water is used, corrosion will occur from the inside, and if the corroded debris gets stuck inside the radiator tube, cooling efficiency will be reduced and the mechanical seal of the water pump will be damaged. If you use tap water, it will corrode from the inside. Coolant is colored red and green to identify it, but the color does not change its performance.

Deterioration over time and insufficient fluid volume can cause overheating and rusting.

Although the amount of liquid is enough, the deterioration of the coolant is remarkable. The color of the liquid is already neither green nor red, though it seems not to have been used only with tap water because the corrosion has not advanced much. If the rubber packing on the back side of the radiator cap is hardened with the peculiarity to stick to the radiator, the airtightness when the cap is closed is decreased, the internal pressure of the cooling system does not rise enough, the boiling point of the coolant is lowered and it becomes easy to boil, so if the packing is deteriorated, the cap should be replaced.

When the temperature and pressure of the coolant rises on the engine side, it flows from the radiator cap to the reserve tank connected by a tube, and when the temperature drops, the coolant returns from the tank to the radiator. When the temperature drops, the coolant returns from the tank to the radiator. It is important to keep the amount of liquid in the tank between F and L. When the coolant is replaced, the coolant in the tank is also replaced.

Coolant is called long-life coolant and has a long life of 2 to 4 years, but its performance degrades over time. Specifically, when exposed to air at high temperatures, the main ingredient, ethylene glycol, oxidizes and forms a white solid, or corrosive substance. When this is clogged inside the radiator tube, the cooling capacity is reduced, just like rust is clogged in tap water. In addition, as mentioned earlier, the cooling system is basically a closed system, but the reserve tank connected to the radiator has a breather tube that is open to the atmosphere, and if the amount of liquid in the tank falls below the lower level due to evaporation as the temperature rises, it will lead to a lack of liquid inside the engine.

Over time, the rust-proofing ability of the system also degrades, and the metal pipes can corrode and develop holes, leading to coolant leaks. Some users may have seen corrosive substances on the connection between rusty metal pipes and rubber hoses. All of these symptoms are due to the deterioration of the coolant.

If you don't notice these signs, or if you spot them but ignore them and continue to use your vehicle, they can cause damage to the water pump and overheating, which will cost you extra to repair. As well as not using tap water on its own, regular replacement is essential even when using coolant. Super Long Life Coolant, which has about twice the life of conventional coolant, is becoming popular for use in automobiles. However, this coolant can only be used in engines designed specifically for this purpose, and it will not extend the life of existing engines that are not compatible with Super Long Life Coolant. It is important that engines that have been developed on the premise of using conventional coolant be replaced at regular intervals.

Periodic replacement is effective to reduce the cleaning time.

Remove the water pump drain bolt to drain the brownish coolant. There is no rust powder mixed in, so it is not tap water but long life coolant, but if you skip changing it, it can deteriorate like this.

It is standard practice to run tap water in the hose from the radiator cap area, and this will clean the area between the lower hose of the radiator and the water pump drain bolt. However, there is a thermostat in the middle of the hose which branches off from the cap part and leads to the top of the engine, so the passage is closed when it is cold. The installation point of the thermostat is different depending on the model, but in such a case, you can rinse the engine by removing the thermostat from the case and pouring water into the hose. If it is troublesome to remove the thermostat, you can inject radiator cleaning agent, warm up the engine, open the thermostat and circulate the cleaning agent, and then drain it.

The dirt in the reserve tank should be removed by shaking the tank well. This is because even if the engine side is cleaned, if the tank is still dirty, the coolant will get dirty as it travels to and from the engine side.

It is advisable to replace the radiator regularly before the symptoms of deterioration are detected, but the procedure is slightly different between replacing the radiator before deterioration and replacing it after specific deterioration has been detected. If it is a normal replacement, the drain bolts of the water pump and piping are removed and the coolant inside the engine and radiator is drained, and the coolant remaining in the reserve tank is also drained. However, if the drained coolant is significantly deteriorated as shown in the example in the image, it is better to flush out the remaining dirt in the cooling system with tap water because it will soon become cloudy even if new coolant is injected.

At this point, it is important to consider that the thermostat is closed when cold. When water from the hose is injected through the radiator cap area, dirt is vigorously drained from the drain area of the water pump, and after a while it turns into clear tap water. If the thermostat between the engine and the radiator is closed, tap water may not circulate inside the engine beyond the water pump even if the coolant is drained. So when rinsing with tap water, it may be useful to remove the thermostat so that the water injected through the radiator cap area can flow into the engine.

howeverDepending on the location of the thermostat and its position in relation to the radiator cap, sufficient tap water may not flow into the engine even if the thermostat is removed.. In such a case, the dirtyYou can make use of cleaner chemicals that can be mixed with the coolant and idled to clean it.I guess.

To avoid this hassle, it is important to replace the coolant at the specified time. Check the condition of the coolant before the summer months arrive, when the load on the cooling system increases, and replace it if necessary.

Editor's Note:.
Ethylene glycol, the main ingredient in Long Life Coolant, is toxic.
Since it has a negative impact on the human body and the environment, the waste liquid should be taken to a specialized company or solidified by absorbing it into a polymer and disposed of as burnable waste.