What you need to know about plate coolers

Marine plate coolers, also known as heat exchangers (read more about their typical failures and remedies in HERE), play a crucial role in the cooling system of marine engines. These compact and efficient devices transfer heat from the engine oil or water coolant to the surrounding seawater or fresh water, helping to maintain optimal operating temperatures. In this blog post, we will explore the benefits and functionality of marine plate coolers, highlighting their importance in enhancing engine efficiency, preventing overheating, and ensuring reliable marine operations.

Example of plate coolers

Plate type heat exchangers are generally used as coolers for water cooling systems, lube oil coolers and as heaters for lube oil purifiers. They are characterized by a very compact structure and good heat transfer grading. By varying the number of plates, the performance can be adjusted and they have low filling capacity, low flow resistance and low thermal inertia. Fluids flow alternately through adjacent plate interspaces according with the counter flow principle and embossing on the plates provide good fluid turbulence and plate stability.

    1. Efficient Heat Transfer: Marine plate coolers are designed with a series of stacked plates, allowing for increased surface area and improved heat transfer efficiency. As the engine coolant flows through the channels formed by the plates, heat is dissipated to the seawater passing through separate channels on the opposite side. This efficient heat exchange process helps to regulate the engine temperature, preventing overheating and maintaining optimal operating conditions.
    2. Engine Performance and Fuel Efficiency: Maintaining the appropriate operating temperature is vital for engine performance and fuel efficiency. Marine plate coolers effectively remove excess heat from the engine coolant, ensuring that the engine operates within the optimal temperature range. By preventing overheating, plate coolers contribute to improved combustion efficiency, reduced wear and tear on engine components, and enhanced fuel economy. Consequently, vessel owners can enjoy longer operating hours and reduced fuel consumption, resulting in cost savings over time.
    3. Corrosion Resistance and Durability: Marine plate coolers are constructed from materials that are highly resistant to corrosion, such as stainless steel, titanium, or cupronickel. These materials ensure the longevity and durability of the plate cooler, even in harsh marine environments where exposure to saltwater and contaminants is prevalent. The corrosion-resistant nature of plate coolers minimizes the risk of clogs, blockages, and other cooling system issues, thus contributing to the overall reliability of the engine.
    4. Maintenance and Cleaning: Proper maintenance and regular cleaning are essential to maximize the performance and lifespan of marine plate coolers.

By understanding their operation and implementing proper maintenance practices is essential to maximize their effectiveness and prolong their lifespan. Further, we will explore the working principle of marine plate coolers and provide valuable maintenance tips to help you keep them running smoothly and reliably.

Working Principle of Marine Plate Coolers

As marine plate coolers are designed to transfer heat from the engine coolant to the surrounding seawater their operation can be summarized in the following steps:

Coolant Flow: The engine coolant is circulated through the plate cooler by a dedicated pump or the engine’s main cooling system. The coolant absorbs heat from the engine components, raising its temperature.

Heat Transfer: As the hot coolant flows through the channels formed by the stacked plates of the cooler, heat is transferred to the cooler’s plates. The large surface area of the plates facilitates efficient heat exchange.

Seawater Flow: Seawater is simultaneously circulated through separate channels on the opposite side of the plates. The cool seawater absorbs the heat from the plates and carries it away, effectively cooling the engine coolant.

Dissipation: The heated seawater is discharged back into the marine environment, while the now-cooled engine coolant returns to the engine, maintaining the desired operating temperature.

Essential Maintenance Practices for Marine Plate Coolers

Regular maintenance ensures optimal performance and longevity of marine plate coolers. Consider implementing the following maintenance practices:

Inspections: Conduct visual inspections of the plate cooler regularly. Look for signs of corrosion, scaling, or damage to the plates, seals, and connections. Address any issues promptly to prevent further damage.

Example of damaged plate cooler

Cleaning: Marine plate coolers can accumulate marine growth, sediment, and debris, affecting their performance. Clean the cooler regularly using appropriate cleaning solutions or marine-safe descaling agents. Follow the manufacturer’s recommendations or consult a professional for specific cleaning procedures. Typically, this involves flushing the plates and channels to remove deposits and maintain efficient heat transfer. Also, sometimes need to be opened and apply mechanical cleaning due hard deposits on the plates’ surfaces.

Back-Flushing: Periodically back-flush the plate cooler by reversing the water flow, to remove salt or impurities that may have accumulated during operation. This prevents the formation of scale and helps maintain the cooler’s performance. The correct back-flushing is done by removing the inner filter before operation.

Pressure Testing: The pressure tests must be performed on the plate cooler to ensure that there are no leaks or blockages that could compromise its effectiveness.

Gaskets and Seals: Inspect and replace gaskets and seals as necessary. Proper seals prevent coolant leaks and maintain the integrity of the plate cooler.

Example of replacing seals on the plate cooler

Coolant Quality: Ensure that the engine coolant used is of high quality and meets the manufacturer’s specifications. Improper coolant can lead to scaling, corrosion, and reduced cooling efficiency.(more about quality testing you can find in HERE)

Professional Servicing: Schedule regular servicing and maintenance with a qualified marine technician. They have the expertise and specialized equipment to perform in-depth inspections, cleaning, and testing of the plate cooler.


Plate cooler troubleshooting involves identifying and addressing issues that may arise with marine plate coolers. By diagnosing and resolving problems promptly, you can ensure the efficient operation of the cooling system and prevent potential damage to the engines and auxiliary equipment. Here are some common plate cooler troubleshooting tips:

Insufficient Cooling: If the engine temperature is higher than normal or the plate cooler seems to be providing inadequate cooling, consider the following:

    • Check for Blockages: Inspect the plate cooler for any blockages or obstructions that may be impeding the flow of coolant or seawater. Clear any debris or fouling that is restricting the flow. Usually this it happens inside filter which can choke in case the your MGPS doesn’t work properly.
    • Verify Coolant Flow: Ensure that the coolant flow rate is adequate. Insufficient flow can result from a faulty pump, clogged pipes, or a malfunctioning thermostatic valve. Address any issues with the coolant flow system.
    • Assess Seawater Flow: Check the seawater intake and strainer for blockages. Make sure the seawater pump is functioning correctly, and the intake valves are fully open. Clean or replace any clogged strainers.

Leakage: Leaks can compromise the efficiency of the plate cooler and lead to coolant loss or seawater contamination. Here’s what to do:

    • Visual Inspection: Inspect the plate cooler, connections, and fittings for any signs of leakage. Look for coolant or seawater stains or drips. Tighten loose connections and replace damaged or worn gaskets and seals.
    • Pressure Test: Perform a pressure test on the plate cooler to identify any leaks. Address any leaks promptly by repairing or replacing the affected components.

Corrosion and Scaling: Corrosion and scaling can reduce the effectiveness of the plate cooler.

Example of leaking cooler due corrosion and seal failure

Take the following steps to address these issues:

    • Cleaning: Regularly clean the plate cooler using appropriate cleaning solutions or descaling agents. This helps remove corrosion, scale, and marine growth that can impede heat transfer. Follow the manufacturer’s recommendations or consult a professional for specific cleaning procedures.
    • Corrosion Protection: Consider using corrosion inhibitors or coatings specifically designed for marine plate coolers. These products help prevent or reduce the risk of corrosion and extend the lifespan of the cooler.

Reduced Heat Transfer Efficiency: If you notice reduced heat transfer efficiency in the plate cooler, take the following actions:

    • Back-Flushing: Periodically back-flush the plate cooler with by reversing the flow in order to remove salt or impurities that may have accumulated during operation. This helps maintain optimal heat transfer efficiency.
    • Consult a Professional: If troubleshooting efforts do not improve the heat transfer efficiency, consult a qualified technician. They can perform in-depth diagnostics, including flow rate measurement, pressure testing, and visual inspections, to identify and address any underlying issues.

Remember, if you encounter complex or persistent issues with your marine plate cooler, it is advisable to seek the expertise of a professional technician or maker representative. They have the knowledge, experience, and specialized equipment to diagnose and resolve more complex problems, ensuring the efficient operation of your cooling system and engine performance.

  1. In conclusion, marine plate coolers are crucial components for maintaining optimal engine temperatures in marine applications. Understanding their operation and implementing regular maintenance practices is essential to ensure their efficiency and longevity. By conducting visual inspections, cleaning, flushing, pressure testing, and engaging professional servicing, you can keep your marine plate cooler running smoothly and reliably. By prioritizing maintenance, you contribute to the overall performance and reliability of your marine engine, ensuring many hours of trouble-free vessel operation.

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