What is Heat Exchanger?
A heat exchanger is a device that cools the engine by transferring heat from the engine’s freshwater coolant to seawater without mixing the two fluids. Coolant flows through small tubes inside the unit, while seawater flows around the outside of the tubes, carrying the heat away.
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What it is
A heat exchanger is a device that cools the engine by transferring heat from the engine’s freshwater coolant to seawater without mixing the two fluids. Coolant flows through small tubes inside the unit, while seawater flows around the outside of the tubes, carrying the heat away.
What it does
The heat exchanger lets your engine run on ethylene-glycol coolant, which circulates inside the engine to absorb and carry away heat. That hot coolant then flows through tubes inside the heat exchanger, where its heat transfers into the raw seawater moving around those tubes. This keeps your engine's internal components clean and corrosion-free while still providing efficient cooling using an unlimited supply of seawater.
Why it matters
A clogged or failed heat exchanger causes engine overheating that can destroy cylinder heads, gaskets and engine blocks in minutes. Tubes blocked by scale, barnacles, or corrosion reduce cooling capacity until the engine can't maintain safe temperatures. Internal leaks allow raw seawater to mix with coolant, corroding the entire engine from the inside out. Heat exchanger replacement is expensive, making preventive maintenance critical.
General Maintenance
Inspect pencil anodes inside the heat exchanger every 100 hours or annually and replace when half consumed. They protect against internal corrosion. Have the heat exchanger professionally cleaned and pressure tested every 3-5 years to remove scale buildup from tubes. Monitor engine temperature closely (gradual increases indicate restricted tubes). Check for coolant mixing with raw water by looking for foamy coolant or coolant in raw water discharge. Keep plenty of spare zincs and gaskets aboard.
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