Wednesday, November 02, 2011

Five Tips to Pump Power into Your Engine

This week, Captain John shares five tips for increasing power to your engine...

Guest blog by Captain John
Author of Seamanship Secrets and publisher of the popular boating education website

Increase throttle speed and your small sailboat diesel engine should accelerate like a stallion on steroids.
But what if it doesn’t?

Unlike their power boat cousins, sailboat engines often get under-used. You see, diesel engines love to be run and run hard. Most sailboat owners use their diesels to putt in and out of a marina slip, tie up alongside a fuel pier, or charge their marine batteries—all at idle speed.

Check these five common trouble areas first if your engine hesitates when you “throttle up”…

1.  Clogged Fuel Filters
Dirt and gunk block a smooth flow of fuel from the tank through the fuel filters back to the engine. If your primary fuel filter has a separator bowl, shine a flashlight through the bowl to check for water or dirt. Drain the bowl of contaminants. Change fuel filters at least once a year in separator and non-separator type fuel filters.

Remember to change the secondary fuel filter (located on the engine near the injection pump) once a year. This filter serves as the final sentry to stop dirt before it gets to the injectors.

Keep your fuel tank 90% full to discourage algae growth on the tank walls. Add a biocide solution to the fuel to stave off harmful microbes.

If you cruise to foreign ports, change fuel filters more often. To be on the safe side, use an in-line filter between the fuel hose and your tank.

2.  Blocked Air Filters
Look for black smoke coming from the marine exhaust hose at the stern when you accelerate. This indicates air blockage, overload (see below) or dirty or clogged injectors (see below). Change your air filters once a year to keep the engine purring like a cat.

3.  Overload Warning Signs
If you know your fuel and air filters are clean, your engine could be working too hard. Check these three things:
  fouled boat bottom (barnacles and algae)
bent or over-sized prop
line wrapped around the propeller shaft (rope, fishing line or trash)

If practical, dive down and check the propeller and shaft. Otherwise, you might need to hire a diver or haul your boat out of the water.

4.  Stuck Valves Create Back Pressure
Small cruising sailboat skippers rarely run their engines at high throttle long enough. Carbon deposits in the cylinders can gum up valves and cause them to stick in the closed position. Back pressure causes your engine to lose power. Change your oil and oil filter twice a year to avoid this problem.

5.  Dirty or Clogged Injectors
When dirty fuel gets past your fuel filter "gate guards", the injectors clog up. Your diesel engine loses power, hesitates or refuses to run. Change your fuel filters at least once a year (see #1).


Cruising boat skippers can expect great service from their small boat diesel engines when they follow these simple preventative maintenance tips. Change your fuel, air and oil filters often to keep your engine running like a top!

Captain John teaches sailing skippers the no-nonsense cruising skills they need beyond sailing school. Sign up for his highly popular FREE sailing tips newsletter at Become a member for instant access to 425+ articles, video tutorials, newsletters, and free eBooks.

Photo © Ju-Lee/ ###

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