Skip to main content

Ten things diesel mechanics think every boatowner should know Page 2

Diesel mechanics is not a difficult subject. In fact, all owners of diesel-powered boats can—and should—learn the fundamentals of operating and maintaining their engines. To run well, a diesel engine requires clean fuel, clean oil, and a lot of air. Routine maintenance will virtually guarantee years of trouble-free service and will keep your busy mechanic at bay.How a diesel engine works,

3. Don’t run your fuel tank dry.

Know your engine’s burn rate (gallons consumed per hour) and your fuel capacity so you can accurately calculate the boat’s range between fill-ups. Do not delay refueling to the point where you have expended nearly all the fuel in your tank. The last 20 percent should be held in reserve. Sucking the last few gallons of fuel from the bottom of the tank increases the chance of pulling water, sludge, and other contaminants—perhaps even air—into the fuel lines. If you’re not sure you have enough range to cruise comfortably between fuel stops, be conservative: Acquire some jerry jugs and take extra fuel with you. You can never have too much fuel, unless the boat is on fire.

4. Know how to bleed air out of your fuel system

Air locks in diesel fuel systems are a fact of life. A typical fuel system has a lift pump (a vacuum pump) that lifts or sucks fuel out of the tank, draws it through the pump, then sends it to the filters and injectors, where an injector pump sends it to the individual cylinders for combustion. Whenever you open the fuel line between the tank and the engine (for example, to change a filter element), air enters the line. Air may also be sucked into the fuel line through cracked seals and gaskets, poorly fitted connectors and clamps, via the pick-up tube in the fuel tank, and so on. This air must be removed, because even a tiny bubble will block the

flow of fuel, which will prevent the engine from starting or will cause it to stop if it is already running.

To clear your fuel line of air, you must “bleed” it out if your engine doesn’t have a self-bleeding feature or it can’t cope with the air. Consult your engine’s manual to identify the appropriate bleeding points; paint them with nail polish so you can find them easily. Given decent access to the engine, bleeding or venting air is a simple procedure that everyone should be able to perform. Use the engine manual to teach yourself how to do this.

While on the subject of air: When running at any speed, diesel engines require an enormous volume of clean air to support combustion. This air is drawn into the engine through a filter. Periodically, that filter should be cleaned with solvent or with kerosene if it’s a metal-mesh filter, or replaced if it is paper or fabric. Even a small reduction in the free flow of air will dramatically reduce the engine’s performance.

5. Be diligent about checking your lube oil and oil filter.

Diesel engines are rough on oil and usually require more frequent oil and oil filter changes than comparable gasoline engines. Follow the engine manual’s recommendation for service intervals—most suggest an oil and filter change after every 75 to 100 hours of operation; some recommend a change every 50 hours. Unchanged oil is probably the single greatest cause of accelerated engine wear and failure. Changing it is one of the simplest maintenance tasks to perform. When changing the lube oil, change the filter element. Carry spares on board. Between oil changes, use the dipstick to check the oil level. Top it off as necessary from an onboard supply, but do not exceed the “full” mark on the dipstick; more is NOT better.

Note that fresh lube oil is golden or honey brown in color. However, after a few minutes of circulating inside the engine, it turns black from soot, ash, acids, contaminants, and other carbon byproducts of diesel-fuel combustion. This is normal and, by itself, is not enough to warrant an oil change.

6. Minimize risks of fire.

Diesel engines vibrate a lot, and a typical marine diesel has a lot of wiring and hoses attached to it. Over time, fasteners loosen and fail and the wiring and hoses come loose. If a loose hose or wire (such as the primary wiring harness, or the power supply to your fuel pump, or a hose to the hydraulic pump) should come in contact with a hot exhaust manifold, for example, any of these could cause a fire.

From time to time, inspect your engine compartment for these potential risks. Add chafing protection, replace worn insulation, and add extra fasteners if necessary. Consider rerouting wires and hoses where appropriate.

Related

00-LEAD-JB13-RT1169

What's it Like to Sail a Legend?

In 1851, the New York pilot schooner America sailed to England, beat the Brits at their own prestigious yacht race (which came to be known as the America’s Cup), and launched an evolution of the East Coast’s pilot craft into vessels that were the envy of the world. Their ...read more

Alexforbes Archangel1-1 (14)

Cape2Rio Draws to a Close

With just four boats still on their way, it has been a long road to Rio for the fleet competing in this year’s Cape2Rio. Larry Folsom’s American-flagged Balance 526 Nohri took line honors and a win in the MORCA fleet, finishing with a corrected time of 18 days, 20 hours, and 42 ...read more

_01-Steve-and-Irene-1

Close Encounters: A Star to Steer By

I first met Steve and Irene Macek in the proper way—in an anchorage full of bluewater cruising boats. This was in St. Georges, Bermuda, in the spring of 2019. Theirs, without doubt, was the most distinctive boat there—an immaculate, three-masted, double-ended Marco Polo schooner ...read more

14_01_230123_TOR_JOF_0414-2048x

The Ocean Race Leg 2 Kicks Off

After a trial by fire start to the race and only a brief stop for limited fixes, the five IMOCA 60 crews in The Ocean Race set off for Cape Town, South Africa, early on January 25. Despite arriving somewhat battered in Cabo Verde, an African island nation west of Senegal, the ...read more

Lead

Cruising: Smitten with a Wooden Boat

I was sailing down the inner channel of Marina del Rey under a beautiful red sunset when Nills, one of the crew members on my boat, pointed out an unusual and unique-looking 40-foot gaff-rigged wooden cutter tied to the end of a dock. Its classic appearance was a stark contrast ...read more

Screen-Shot-2023-01-23-at-12.03.19-PM

Racing Recap: Leg One of The Ocean Race

New to spectating The Ocean Race? Managing Editor Lydia Mullan breaks down everything you need to know to get started. ...read more

image00001

From the Editor: Keeping the Hands in Hands-On

SAIL Editor-in-Chief Wendy Mitman Clarke enjoys a sunny autumn cruise in her Peterson 34 on the Chesapeake Bay. It was late afternoon just after the U.S. Sailboat Show in Annapolis when I climbed aboard the last boat on the schedule. I and others who review and sail boats for ...read more

P1580711

B&G Announces New Zeus S Chartplotter

B&G has long been putting out top-of-the-line electronics, but the new Zeus S Chartplotter is a new take on the best way to give sailors the exact information they need, when they need it. “So many more people sail shorthanded these days, whether as a couple or when they’re ...read more