Power & Propulsion — Engine Room Test
Diesel fuel is not only burned in the engine, it also lubricates and cools key components. To keep fuel temperatures within acceptable levels, fuel is run through this device which looks like a large tube usually mounted on the side of the engine and connected to two pairs of hoses. The larger pair carries seawater while the smaller one carries fuel. There is a similar but smaller unit on the marine transmission to cool transmission oil.