J/Boats J/109 Owner's Manual - page 36
J/109 OWNER GUIDE
36
Engine Cooling System
The J/109’s engine utilizes both a “closed” cooling system, in which a mixture of fresh water and
antifreeze is circulated within the engine, and a “raw water” system, in which a heat exchanger supplies
a constant flow of outside water, pumped in through the raw-water intake, to cool the coolant mixture.
Coolant system. The filler cap (it looks like a radiator cap) for the freshwater-and-antifreeze cooling
system is located on top of the engine manifold. Check the coolant level of the manifold and the
coolant subtank aft of the engine, on the port side of the compartment (check when the engine is
cool). When adding coolant, follow the engine manufacturer’s recommendations for the proper fresh
water/antifreeze ratio. In climates where freezing may occur in winter, test the coolant mixture for
freezing point. Add coolant as needed if the system is not drained for winter storage.
Raw-water system. Located furthest aft in the engine compartment, the J/109’s raw-water strainer
helps prevent clogging of the raw-water cooling system and overheating of the engine. Check the
strainer basket often to insure that the flow of cooling water is unimpeded. Unscrew the strainer basket
lid, remove the strainer and clean it, and be sure that the basket is seated properly in the bowl before
screwing the lid on hand-tight.
Exhaust System
The J/109 is equipped with a water-injected water-lift exhaust system that dissipates exhaust heat and
acts as the exhaust muffler. Cooling water can accumulate in the bottom of the water-lock muffler;
when de-commissioning your boat for the season, the muffler either should be drained by unscrewing
the drain plug on the bottom of the muffler, or antifreeze should be added so that residual water
doesn’t freeze. The water-lock muffler can be accessed via the starboard-side cockpit locker in the
chaseway under the cockpit.
General Hints To Avoid Problems
•
Monitor brightness of cabin lighting and charge batteries as required by running engine. Batteries
are charged by either the AC battery charger or by running the engine.
•
Stop engine with throttle fuel cut-off, then turn ignition key “off”.
•
NEVER turn engine battery switch to OFF position while engine is running.
•
For best efficiency and fuel economy a cruising R.P.M. of 2,600 - 2,800 works well. Vary RPM
levels periodically when cruising under power for a long distance. Be sure to thoroughly read and
follow the manufacturer’s manual for proper break-in procedure for the standard turbo charged
Yanmar Diesel engine. When not underway, battery charging and refrigeration cooling should be
handled via shore power or an auxiliary generator.
•
Do not run engine at full throttle (3600 RPM) for sustained periods, as breakdown may occur.
Most importantly, find an RPM that runs smoothly and follow the Yanmar guide. Avoid "vibrating"
RPM speeds when possible.
•
Keep engine gear shift lever in "REVERSE" position while sailing to prevent possible "free-
wheeling" of prop
•
CAUTION: The J/109 engine is very quiet, and it is possible to forget that it is running. Before
shifting the gear shift lever into REVERSE when sailing, double check that the engine is turned off.