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www.marinelink.com MN 21 deposit on internal surfaces, reducing heat transfer and degrading the lubricating and cooling properties of the coolant. Other stresses to the coolant come from the exotic met- als that are used in today’s modern engines, such as iron, aluminum, titanium and copper-nickel. Dissimilar metals increase galvanic corrosion opportunities unless the coolant is maintained at the right pH with the right blend of inhibitors. The same issues are present in the charge-air coolers that are used to cool the pressurized air from the turbochargers and densify the oxygen that improves com- bustion. Here, temperature differentials are even higher, with charge-air temperatures upwards of 300 degrees F going across the charge-air cooler. To make sure that the coolant is operating at top effi- ciency, it needs to be properly tested annually. Coolant samples should be sent to a laboratory to check the pH, identify any metals or salts that are present, and to evalu- ate the condition of the lubricants and corrosion inhibitors. Testing kits are readily available from your engine manufacturer. AIR INTAKE SYSTEM To ensure the best possible fuel efficiency, always replace air filters at the manufacturer’s recommended intervals. Frequent inspection of the condition of the filters between changes is also important to make sure they are not being contaminated by oil mist from a leaky crankcase or soot from leaks in the exhaust system feeding back into the engine compartment. Turbochargers are another part of the air intake system High reliability, low fuel consumption and long engine life are all results of regular marine engine maintenance. Images cour tesy MTU
