In the cooling system of an internal combustion engine, it is mandatory to use antifreeze – and only qualified antifreeze should be used. Do not use ordinary water easily, especially hard water with a high content of minerals, because once scale forms in the engine’s cooling channels, it is almost impossible to completely remove it – this is also one of the common high-temperature problems in the cooling systems of old engines using ordinary coolant. And qualified antifreeze does not cause scale;
Regarding antifreeze, there are two specifications for its application range: one is heavy-duty antifreeze, mainly used in diesel engine cooling systems, and the other is light-duty antifreeze, used in the cooling systems of passenger cars – if the person selling you the antifreeze doesn’t even know which type it is? I advise you to better buy from another supplier;
Modern internal combustion engines, due to their sophisticated design and requirements for small size, are no longer comparable to traditional internal combustion engines – for example, the 6135 series engine requires four buckets of water for the cooling system, nearly 100L, and the radiator is also large, and the water jacket capacity is also large;
For engines of the same power, approximately 30L of coolant is enough now, so modern internal combustion engines have higher requirements for coolant and cooling performance.
In fact, the main reasons for excessively high coolant temperature can be categorized into two types:
- Poor cooling performance of the system. This is the most common and widespread issue. The specific manifestation is that the water temperature of the engine rises rapidly and is more sensitive to changes in temperature. The most common causes are generally related to – slipping of the belt, fan speed lower than the standard value, and many problems arise from here. Often, the recycled second-hand machine’s coolant temperature is excessively high, and many of them are caused by belt slipping. The belt wears out to the point where it becomes as hard as a steel bar, and adjusting the tightness of the belt to the point where it is as rigid as a steel bar is not achievable! Because the V-belt transmits power through both sides, if the belt wears out, it will sink into the groove of the pulley and even some belts have already touched the bottom of the groove. Pulling the belt apart is not enough to achieve the required friction force!
Here is a method for checking the wear degree of the belt – this item is not mentioned in any maintenance manual – if the belt is adjusted to the appropriate tension and the upper surface of the belt is already flush with or even depressed against the outer surface of the pulley, replace the belt.
So, the most common problem of poor cooling is that the fan speed does not meet the requirements; here there are many causes, such as the pulley, belt, fan clutch, etc.;
Insufficient cooling air flow is also a common cause of problems;
When the fan speed meets the requirements, it may not necessarily meet the requirements of the cooling system – there is also the cooling air flow!
If the cooling air flow is insufficient, the air passing through the radiator cannot remove the heat generated by the engine, and the cooling system remains at a high temperature!
The common cause of this problem is that the surface of the radiator is clogged, with dirt adhering, the windward area is blocked, the air circulation route is bypassed, or even the fan is installed in the wrong direction [for some models, the fan on both sides is symmetrical, and if not careful, it is very easy to install it wrongly], buy a wind speed meter – that thing that measures strong wind – after summarizing, test at the specific position of the machine, and immediately know the air flow and pressure of the cooling system. If it is normal, then test other aspects.
The performance of the water pump declines – I have encountered some machines where the water pump impeller was worn down by about 1/5!
The radiator is clogged internally, or with dirt, or scale. If it is not thoroughly removed, replace the radiator!
The engine surface is dirty, which can also cause poor heat dissipation;
Some machines have parallel hydraulic oil and coolant radiators, while others are in series. There are different heat dissipation characteristics, and there are special cases, such as a 500-horsepower 12-cylinder water-cooled engine that has no fan – it cools by exhaust ejector; - The engine generates excessive heat;
This is one of the common causes of overheating in old machines;
Insufficient engine power, failure of the cooling system thermostat [large machines have more than one thermostat], severe overload, incorrect fuel timing, excessive fuel injection leading to poor combustion, failure of the intercooler, abnormal injection pressure, poor lubrication of the crankshaft and connecting rod mechanism causing excessive friction resistance, can all cause the machine to emit heat far beyond its designed heat dissipation capacity, causing the cooling system to exceed its maximum working capacity and resulting in the machine overheating. If the hydraulic system of the machine is severely worn and leaking, and coincidentally the hydraulic oil radiator and the engine cooler are arranged in series, the hydraulic oil will heat the engine! Don’t think that adding extra cooling fans to the machine can solve the problem. If the fault cause is not eliminated, the high-temperature phenomenon will continue to worsen. There are many other reasons that have not been listed one by one. Therefore, the causes of the cooling system failure are not trivial matters. They require careful and meticulous resolution.