Back in the old days, most marine engine cooling systems relied on raw seawater to cool the vessel down. The problem with the method is that seawater came with a myriad of other compounds ranging from saltwater to pollution and algae infestation.
It pretty much means that whatever liquid that is readily available around the boat is pumped into the system to cool it down. Naturally, the durability and longevity of engines became an issue due to the corrosive nature of saltwater which forced engine manufacturers to produce closed system and freshwater cooling engines. The concept focuses on using antifreeze or coolant to cool the internal aspect of the engine while cooling the external with a radiator, also known as a heat exchanger.
Similar to a car radiator, the marine vessel radiator’s purpose is to shed heat away from the closed side of the engine.
Fast forward to today, and you’ll find that most new marine vessels are designed with a closed cooling system ensuring durability with time. To enhance the effectiveness of the coolant, the systems are pressurised. This means for every half kilo added, approximately 16° C can be added to your vessel’s operating temperature, thus improving thermal efficiency.
As for the radiator aspect of your marine vessel, calcium and lime deposit build-ups are an inevitable part of the system, which will lead to reduced cooling of the engine. To maintain optimal performance, those deposits need to be regularly flushed out with a recommendation of once every three months. It is also recommended that you change the coolant once every couple of years with an obvious preference to following your engine manufacturer’s maintenance recommendations.
Marine vessels face a noticeable difference in the way the engine cools down. Comparative to automobiles where air is the primary cooling agent, the marine application relies on seawater, river water or lake water to get the job done. This is where things get complicated when it comes to maintenance of your marine vessel.
An effective way to get rid of the calcium and lime deposits is to acid dip and boil the radiator. You could get this done through your local automotive radiator repair shop. However, these days, you may be pressed to find one that still provides the service.
The best way around it is to look at prevention being better than cure. In this case, your first line of defence should be a raw water filter to keep the large debris out. You can expect microorganisms like calcium and lime to get through the filter screen, but at least you’ve mitigated any significant particle blockages in your cooling system.
Having lime and calcium build-ups within your radiator passages will lead to a physical blockage of cool water flow. Interference with the radiator system could also be of an issue due to the reliance on convection and conduction to cool your engine down. Any build-up of coating on your radiator tubes will block heat transfer and reduce the overall efficiency of your radiator.
To counter the issue yourself, flush the raw water side of your system every year with a radiator flush. Before flushing, make sure to remove the sacrificial anodes screwed into your radiator and replace them with new ones after the flush.
Other must do’s to ensure optimal performance of your marine vessel all year round includes:
- Checking and testing your engine coolant to ensure it meets an adequate temperature for protecting your engine. You can do this by using an antifreeze hydrometer which can be purchased at almost any automotive parts store.
- Testing the pressure cap on your cooling system every three to four years as these do wear out with time and are often forgotten.
Follow these guidelines above, and your engine will be one cool operator all year round.