DIESEL ENGINES "D
iesels love their oil like a sailor loves his rum." This iconic line uttered by Captain Ron in the classic sailor's comedy of the same name was a warning to the boat's owner to keep the oil-burning engine topped up. But this advice doesn't necessarily hold true for all diesel engines. Advances in design and technology have yielded diesels that are practically bullet-proof, if cared for correctly and consistently. The fact that practically each model from any given manufacturer comes with its own,very specific maintenance schedule means that before you perform any task on your engine, you should always refer to the manual that came with it. If you bought your boat used or you've misplaced the engine manual, stop what you're doing and go find one. Whether you download it from the manufacturer's website or buy a used one off eBay, make sure it's the manual for your specific model. Then let it be your 'engine bible' and follow its instructions to the letter. In the meantime, this article will outline a handful of basic maintenance chores that will keep your diesel chugging along for years to come.
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ou don't need to know exactly how a diesel works to keep it in top running condition, but it doesn't hurt, either. Diesels are deceptively simple and need just three things to run: fuel, air and compression. If one of these is missing from the equation, that hunk of iron in the bowels of your boat might as well be a gigantic paperweight. Here's the Reader's Digest version Heat Exchanger/ Exhaust Manifold
of how a diesel engine works: Inside the engine is at least one cylinder that houses a piston. A big electric starting motor initially turns the piston, which pushes up to compress the air inside the cylinder. The air becomes super-heated when it's compressed and, at this point, diesel gets sprayed into the cylinder by an injector. A small 'explosion' forces the piston back down and inertia takes over from there. There are, of course, many other details involved, but this is the basic, stick-figure drawing of how a diesel engine works.
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aintaining a diesel engine is probably one of the more psychologically daunting tasks for many boat owners. There are about a kajillion little — and big — parts that are a total mystery. For many, the easiest thing to do is simply ignore the beast until it gives you trouble, then call in professional help. Unfortunately, by taking this head-in-the-sand approach, you're signifThermostat Housing icantly hin(remove to access thermostat) dering the performance — as well as Alternator shortening the life — of your engine. The good news is that if you perform a handful of basic main-
Fresh Water Filler (coolant goes In here) Fresh Water Pump
Mixing Elbow
be it. Technically speaking, that's three things, as you'll have the air, oil and fuel filters to change. But doing so will go a long way toward keeping your engine purring like jungle cat. AIR Diesel engines consume a tremendous amount of air. While the marine environment isn't known for its gritty nature, dust from boat work, sand in desert locales, and pet hair can wreak havoc on an engine if not filtered properly. The tiniest dirt particles can score the soft metals inside the engine, which can lead to costly repairs. The safest bet is to replace your engine's air filter at regular intervals (check your owner's manual for a timeline), regardless of how clean it looks. This is undoubtedly the easiest and cleanest task associated with your engine, so enjoy it while you can!
OIL Changing the oil filter in your engine Oil Filler (oil goes in here)
Air Intake (air filter underneath cover) Mixing Elbow
Oil Filter Starter Solenoid Starter
Dipstick (pull out to check oil level) Fuel Filter
Raw Water Pump
tenance tasks, your engine can happily run for thousands of hours. If you perform just one maintenance task on your diesel engine, changing its filters frequently should
almost always requires changing the oil, as well. Even if it didn't, it hardly makes sense to change the filter and not the dirty oil that needs filtering. Again, you'll have to reference your owner's manual because there are several different methods for changing the oil in an engine, depending on its design. Our Yanmar, for example, requires the use of an oil extractor — stick the hose in the dipstick tube and pump away. Other engines have drain plugs on the bottom
