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How Scale and Deposits Harm Cooling Systems

There is a lot to consider when maintaining a diesel engine cooling system. Even if every precaution is taken, some harmful substances are bound to accumulate over time. Like normal wear-and-tear on the engine, cooling systems experience the natural buildup of scale and deposits as a byproduct of the coolant needed for the system to do its job. The key is to understand where these formations come from and take basic steps to limit them as much as possible.

The problem of scale and deposit buildup is ultimately tied to the nature of the engine coolant. Specifically, it comes from the water being used in the mixture. If you need a refresher on the different types of coolant and how they work, read our previous post. Basically, coolant is a liquid mixture of water, antifreeze and some other additives. It sounds simple, but the problem is not all water is the same.

scale deposit on water pump in diesel engine cooling system

Variation in water quality is caused by one or more characteristics, including pH level, calcium and magnesium hardness, total hardness and temperature. If you’ve ever noticed how tap water can taste very different depending on where you get it, that’s because of differences in water hardness. Hard water means water with a high mineral count. Soft water has a low mineral count. In general, hard water is bad for engine coolant unless it’s been pretreated. Water with high mineral count causes buildup more quickly, which will hurt cooling system performance over time.

There are minimum acceptable water requirements for different types of diesel engine. These must be carefully considered when mixing coolant. Consult an expert for water analysis to make sure your coolant has the right water and additives to help protect your engine model. This is important not only to prevent scale deposits, but also corrosion, including cylinder liner pitting and cavitation.

So what happens if you don’t use the correct coolant for your engine, or neglect your cooling system maintenance? You’ll eventually see a buildup of hard scale or other deposits on system parts. Deposits can look different depending on their root cause. Some look like a thin film while others are thick and viscous. Scale is a particular type of deposit caused by the growth of crystals on surfaces in contact with water. Common scale compounds are calcium carbonate, calcium sulfate, iron, copper, silica and lead.

Some areas of the cooling system especially vulnerable to scale buildup are those where high-temperature water comes in contact with metal or other rough surfaces. Water temperature, pH level and the presence of salt above minimum acceptable solubility levels are all contributing factors to the problem of scale deposits.

How do scale and other deposits prevent your cooling system from working properly? The more buildup there is, the more it acts as insulation throughout the system. That means it is preventing the coolant from transferring heat to the radiator/heat exchanger and out of your engine. The more heat that becomes trapped, the less efficient the system is working and the higher the risk of serious engine damage. Even a relatively thin scale deposit can reduce heat transfer by as much as 40%!

No one should expect to completely avoid deposit formation in their diesel engine and cooling system. But having a basic understanding of the causes and a sound maintenance plan will help prevent major scale and deposit buildup. Call us at Industrial Radiator Service and our trained technicians will diagnose and fix any buildup in your cooling system. We will also set you up with a regular maintenance plan so your equipment stays in top shape for years to come.

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