Seamanship_Secrets_185_Tips_-_Techniques_for_Better_Navigation-_Cruise_Planning-_and_Boat_Handling_Under_Power_or_Sail_(Re)_e..

diesel engine maintenance and powerboat seamanship 155

While he worked, I asked questions about anything I wasn’t quite sure of.
He always had a smile and tons of patience. But his most memorable advice
was, “Don’t worry about anything if it’s not in your owner’s manual. But if it
is, do it before the manual tells you to.” That advice served me well. The little
Yanmar ran flawlessly for the five years I owned Winged Victory.
Whether in an auxiliary-powered sailboat or a power vessel, you can achieve
this same reliability by taking care of the fi ve most important engine systems,
the systems I call the Big Five: the cooling system, the lubrication system, the
fuel system, the air system, and the charging system. Maintain these and your
engine will run like a top. Ignore them and trouble is sure to follow. First and
foremost, read and follow your owner’s manual to the letter.

THE COOLING SYSTEM
My little diesel was straight raw-water cooled, which means that it lacked a
heat exchanger. Instead, raw seawater circulated through the engine’s inter-
nal passages, removing heat. Th ese days most engines have a recirculating
freshwater cooling system in which a mixture of fresh water and antifreeze
circulates through the engine’s internal passages. Th e heat removed from the
engine by this coolant is then transferred to raw seawater through thin-walled
tubes in a heat exchanger, and the heated seawater is then injected into the

secondary

fuel filter

oil dipstick

raw-water inlet

(to seacock)

exhaust

elbow

starter

solenoid

starter

heat exchanger

alternator coolant pressure cap

oil sump

raw-water circuit drain drive belt

raw-water

impeller pump

freshwater pump

(under cover)

A diesel engine provides hours of reliable operation if given proper basic checks and
preventive maintenance (see next page, too). (Yanmar Marine)