Question 65 OSE02 - Assistant Engineer - OSV

The Correct Answer is A. Maintaining a tight system and promptly repairing leaks (Option A) is the best line of defense in minimizing cooling system problems, especially when the quality of the make-up water is questionable. The closed, recirculating cooling system relies on the chemical treatment (coolant) package to protect the engine components from corrosion, scaling, and cavitation erosion. If the system is tight and free of leaks, the need for adding fresh make-up water—which is the source of the questionable mineral content (dissolved solids, chlorides, etc.)—is minimized. This keeps the concentration of the protective chemical additives stable and high, preventing the introduction of harmful minerals that accelerate depletion of the treatment package and cause scaling or corrosion. **Minimizing the intake of poor-quality water is the primary defense.** **Why the other options are incorrect:** * **B) Maintaining cooling water temperatures at lower-than-normal values:** Operating the engine below its design temperature range is detrimental. Low temperatures can lead to incomplete combustion, acidic condensate formation (cold corrosion), poor lubrication, and sludge buildup, increasing overall engine wear and system fouling. It does not address the mineral content issue. * **C) Increasing the frequency of draining, flushing, and re-filling the system:** While necessary periodically, doing this too frequently is counterproductive when make-up water quality is poor. Each drain and refill event introduces a large volume of the questionable fresh water, depleting the chemical additives and increasing the risk of scaling and corrosion from the new mineral content introduced with the fresh charge. It also increases operational cost and downtime. * **D) Maintaining cooling water temperatures at higher-than-normal values:** High temperatures accelerate chemical reactions, including the degradation of the protective additives (coolant breakdown) and the precipitation of dissolved minerals (scaling). Excessive heat can lead to overheating, component damage (e.g., cylinder head cracking), and rapid cooling system failure.