What is the danger of engine coolant temperature too high or too low?

Presumably, you and your friends all know that when the diesel engine is working, the fuel burns a lot of heat. Generally, the gas temperature in the cylinder can be as high as 1800-2000°C.

Dongfeng Cummins special coolant

It can be imagined that if the cooling system malfunctions, the coolant temperature is too high or too low will affect the normal operation of the diesel engine, and even breakdowns and accidents. Today Xiao Bian talked to everyone about "these things about coolant temperature"

The effect of high coolant temperature on diesel engine

1, poor lubrication. If the coolant temperature exceeds 95°C, the temperature of the lubricating oil will increase and become too thin. It will be difficult to form a lubricating film with the secondary surface, and semi-dry friction or even dry friction will occur. At the same time, because the cylinder temperature is too high, the cylinder wall oil is easy to scorch and deposit carbon, which promotes accelerated wear of the components. In severe cases, it can cause accidents such as pulling cylinders, holding shafts, and burning tiles.

2, damage and clearance. When the metal parts of the diesel engine are subjected to high temperature for a long time, the strength, elasticity, and wear resistance will decrease. At the same time, the high temperature causes the parts to expand and deform, seriously affecting the normal clearance of the mating parts, and even causing seizure.

3, aeration efficiency is reduced. The air entering the cylinder is thermally expanded, the air density is reduced, and the aeration efficiency is reduced. Due to the relative reduction in the intake air volume, the air-fuel ratio becomes smaller, the combustion is not sufficient, the exhaust pipe emits black smoke, and the output power of the diesel engine decreases.

The Effect of Low Coolant Temperature on Diesel Engine

1, increase the loss of machinery. The temperature of the coolant is too low, so that the temperature of the lubricant is reduced and the fluidity thereof is deteriorated. This not only increases the wear of the component, but also increases the mechanical loss due to the increase of the frictional resistance.

2, resulting in corrosion of the cylinder wall. The temperature of the cylinder is too low and the water vapor in the cylinder easily condenses on the cylinder wall. Some of the combustion products (such as sulfur dioxide) generated during the combustion of diesel encounter the water on the condensed cylinder wall, and the cylinder wall will form a strong corrosive agent (sulfurous acid, sulfuric acid) adhering to the cylinder wall. The cylinder wall is thus subjected to strong corrosion, which loosens the surface metal structure. When the cylinder sleeve and the piston ring rub against each other, the metal surface layer falls off, or pits or pits appear on the working surface of the cylinder sleeve.

3. Increased heat loss. The diesel engine works at a low temperature, and the cooling fluid takes a lot of heat energy in the cylinder, so that the heat loss increases; due to the incomplete combustion of the fuel in the cylinder, not only will the oil film of the cylinder wall be flushed, the oil of the oil pan will be dilute, and the fuel consumption will be increased. , Reduce output power.

4. Burning worsened. In diesel engines, the high temperature of compressed gas is a necessary condition to ensure the ignition of fuel. When the temperature of cylinders, pistons and other parts is too low, it will cause the compression end temperature to drop, fire delay, combustion deterioration, fuel combustion is not complete, work is rude, row Black smoke.

A good habit to ensure that the cooling water temperature is not abnormal

1, check or replace the coolant regularly

Various anti-rust agents and anti-foaming agents are added to the coolant to effectively reduce the rust of the cooling system and the generation of coolant bubbles. After a long period of use, these additives will be consumed, so we need to replace the new coolant regularly.

2, can not use water instead of coolant

In the daily-use car process, we must not use water for long-term instead of dedicated coolant. Water can only be used as an emergency in special circumstances.

First, the boiling point of water is lower than that of a dedicated coolant, and it is easier to evaporate. Therefore, when using water as a coolant, it is necessary to add it frequently. Secondly, the untreated water contains more minerals. After long-term use, it will generate scale in the water pipes. When the scale is accumulated to a certain extent, it will reduce the water circulation efficiency in the water pipes, affecting the cooling effect of the cooling system. .

Finally, it is very easy for water to freeze in winter, especially in the north. After the vehicle is parked overnight, the water in the tank will swell and swell, causing serious damage to the body.

3. Periodically remove dust from water tanks and engine compartments

In the process of driving the vehicle, the high-speed wind hit on the face can help to take away the heat from the surface of the tank. If the surface of the tank is more dusty, the cooling effect during driving will be greatly reduced.

When cleaning the water tank or the dust in the engine compartment, we should avoid flushing the water directly into the engine compartment. This may cause the wire connectors to fall off and damage the electronic components. The correct approach should be to use a high-pressure air gun to blow to the dusty location. It is suggested that every time the vehicle is being serviced or washed, the service station maintenance personnel or the car wash shop staff should help clean up the dust in the engine compartment with the air gun.