The 60-Second Pre-Start Check

Recall from card #1 that a marine diesel burns fuel by compressing air until it's hot enough to ignite — a violent, hard-working process that depends on a few support systems staying healthy. The single most common way to wreck one is to hit the start button before checking those systems. A quick walk-around takes under a minute and prevents the two failures that ruin engines: running dry and running hot.

Check four things, every start. Oil: pull the dipstick, wipe it, reinsert, and read the level — it should sit between the low and high marks. Low oil means metal parts grind without lubrication; oil that looks milky-grey means water has gotten in. Coolant: open the header tank (only when cold) and confirm the level is up to the mark — this is the fresh water that carries engine heat away. Belt tension: press the alternator/water-pump belt with a thumb; it should deflect about 10–12 mm (½ inch), no more. A loose belt slips, so the water pump under-pumps and the alternator under-charges.

The fourth is unique to boats: the raw-water intake. Your engine is cooled by seawater drawn in through a hull fitting (the seacock), so before starting you must open that seacock. After starting, immediately look over the stern — you should see water spitting out with the exhaust. No water at the exhaust within ~15 seconds means shut down now: the raw-water pump's rubber impeller runs dry and shreds in under a minute, and the engine will overheat.

Think of it as a fixed order: oil, coolant, belt, seacock — then start, then confirm water overboard. The same loop, every single time.