Insured & Factory Certified Technicians
The fuel cooler is a simple seawater cooled element responsible for cooling the fuel before it is returned to the tank. A large amount of the fuel that is drawn up to the engine is not used. The fuel that isn’t used is sent back to the tank via the fuel return line. As this fuel passes through the engine, it is heated. When the heated return fuel exits the engine, it is routed through the fuel cooler element. Inside the fuel cooler, the fuel passes over tubes that have seawater flowing through them, thereby cooling the fuel.
The fuel cooler is often an overlooked maintenance item because, with large tanks full of fuel, the fuel temperature doesn’t normally go up much, even when the seawater portion of the cooler is clogged and not transferring heat well. Although temperature is rarely a problem, the fuel cooler is necessary for those instances where conditions are severe, fuel levels are low, and the fuel temperature could become an issue.
The most common failure associated with the fuel cooler is a rupture in the element that allows seawater to contaminate the fuel system. Seawater can be disastrous for the fuel system. What’s worse is that a fuel system that has been compromised can cause major internal engine damage due to improper fuel metering/atomization in the cylinders. After a rupture, the seawater can contaminate the fuel system quite quickly and in large amounts, and the operator won’t be aware until there is already a problem. By this time, the seawater can have already caused major damage.
Due to the relatively low pressures that the fuel cooler sees, a weakened element may function without any leakage for some time. Often times a weakened element will leak after being cleaned and pressure tested at a higher pressure than the it usually sees. If for no other reason than this, the fuel cooler maintenance is a good idea, because it is our only opportunity to test the integrity of the element and verify that it is still a reliable unit.
Fuel cooler maintenance consists of simply removing the cooler and having it ultrasonically cleaned at a radiator shop.