Construction machinery cannot operate properly without the assistance of a cooling system. Maintaining this system is one of the key factors that ensures your machine works normally and efficiently.

Since there are many different types of construction equipment, the cooling capacity of their engines varies, and there is no single fixed cooling standard. However, at a minimum, the system must be able to meet the machine’s own operational requirements.
Except for small local manufacturers, most major OEMs have their own standards — for example, stating that their machines can operate normally at an ambient temperature of “XX°C.” This represents the manufacturer’s design commitment.

However, after several years of operation, it is difficult for a machine to continue meeting its original factory standards. The cooling performance and heat dissipation conditions will inevitably deteriorate — this is quite normal. If manufacturers had originally designed excessive cooling margins, that would have been wasteful in two ways:

1. It would consume extra engine power unnecessarily.

2. It could cause the engine to run too cool, leading to low-temperature wear.

Therefore, the cooling system’s capacity must be balanced, not excessive.

When the engine begins to overheat, it’s necessary to test the cooling system’s performance and understand the original manufacturer’s specifications. Only by comparing test results to those factory benchmarks can you properly restore the engine’s cooling performance.

This means learning about various parameters of different machine brands and models, such as:

• Maximum cooling fan speed

• Cooling air pressure

• Airflow rate, etc.

Some machines use hydraulic or coupling-driven fans rather than belt-driven ones, so it’s important to know the factory standards for each type. Due to various practical reasons, many owners find it difficult to meet these requirements — which is why learning the relevant knowledge is so important.

By obtaining and understanding this data, you can make an initial judgment about whether your cooling system still meets factory standards. To do this, you must understand basic testing conditions — and that requires some study. At the very least, you’ll need:

• A tachometer (to measure speed)

• An infrared thermometer

• Knowledge of how to use them

This isn’t too demanding — after all, it’s your own machine. Learning these basic diagnostic methods means you can perform preliminary checks by yourself, without relying on others. Very few people will test your machine for free, so it’s better to do the initial checks yourself. With just a small investment (around 100 RMB), you can collect meaningful test data.

Having this baseline data also helps you communicate more effectively when you do seek technical help — otherwise, without any data, others are just guessing. Many operators suffer from this “blind repair” approach, which is unreliable and inefficient.

For example, once you’ve measured the fan speed, you can tell whether there’s excessive belt slippage. A belt drive typically has about 95% transmission efficiency (since all belts slip to some extent). Hydraulic drives, on the other hand, have lower transmission efficiency but offer stronger drive power and speed adjustment capability. So if your measured fan speed meets the requirement, the problem likely lies elsewhere.

When testing fan speed, it’s not enough just to have the right tool — you must also know the correct testing procedure:

1. With the engine off, attach a reflective strip (supplied with most tachometers) to the fan.

2. Start the engine and allow it to run until the coolant temperature reaches at least 90°C and stabilizes within that range.

   • If it cannot stabilize, take insulation measures such as using a temporary radiator curtain.

3. Measure the maximum fan speed with the tachometer from the proper distance.

4. Record three separate readings, calculate the average value, and document it properly.

Only with accurate data like this can you determine whether the fan’s performance meets the required standard — rather than simply swapping in some cheap aftermarket fan “to see if it works,” which often wastes both time and money.

Although these may seem like minor details, they actually reflect the true health of your machine, providing a reliable basis for diagnosing faults. It’s worth taking this seriously.