OPERATING MANUAL FOR BUKH DV48ME ENGINES
009W0227-R01 - 8 -
Freshwater cooling
When using freshwater cooling it will be possible to reach a higher
operating temperature of 70-95°C which will prolong the life of the
engine. This cooling system is recommended for engines operating
for more than 500 hours a year.
A pump circulates the freshwater in a closed system.
This circulation pump is fitted on the back end of the engine. The
fresh water circulates through the cooling jackets of the engine and
through the heat exchanger fitted on the water-cooled exhaust
manifold. The freshwater is cooled in the heat exchanger by
seawater which is pumped through by a big impeller pump like the
one used for direct seawater-cooling.
The seawater leaves the heat exchanger via the exhaust system as
in the case of seawater cooling.
Frost precautions
To avoid damaging the engine, drain the cooling water during frosty
periods.
To protect the engine against damage caused by frost, proceed as
follows:
1. Turn off the cock on the cooling water inlet skin fitting.
2. Drain the cooling water off the engine by removing the plug
above the lubricating oil filter on starboard side and under the
exhaust manifold, respectively.
3. Clean up the drain holes with a nail, a steel wire or the like, so
that any remaining water may drain out.
4. Start the engine and let it run for 30 seconds to remove all the
water from engine and exhaust manifold. Running for that short
time will cause no damage to the impeller of the pump.
On engines fitted with heat exchanger cooling it is recommended to use a mixture of min. 30% antifreeze liquid and 70%
water and max. 50% antifreeze and 50% water as protection against corrosion and to secure the cooling water freezing
temperature to min. minus 15° Celsius or lower if required from climate conditions.
However please also note when doing service on the boat that the mix of water and antifreeze can get aggressive and
start corrosion. If corrosion is found in the cooling system it can be caused by one of two conditions:
1. The anti corrosion additives in the anti freezing liquid are exhausted and have evaporated.
2. Oxidation due to incoming air causing an acid which is lowering the PH value.
Therefore and also to keep the anti freezing properties it is recommended to change the cooling water and antifreeze
every 3 years min. Please also note the details provided by your supplier of antifreeze liquid normally stated on the can.
Heat exchanger freshwater capacity for DV36 is approx. 7.0 litres.
Drain the raw water from the heat exchanger cooled engines by taking off the seawater pump cover.
Electrical System
The engine is equipped with a 12 volt electrical system consisting of a starter motor and an alternator, the max.
charging current of which is 50 Amp.
Electrical wiring diagram for the engine with control and instrument panels is shown later in this instruction.
The level of the electrolyte in the battery should be checked every 14 days or every 25 operating hours. The level
should be 5-6 mm above the plates, if this is not the case top up as required with destilled or demineralized water.
The battery must never be isolated from the alternator, when the engine is running.
Warning! It is not allowed to connect additional equipment to the wiring system on the engine. Possible additional
equipment has to be connected directly to the terminals of the battery.
NOTE!
The starter must not be operated for more than 10 sec. If further operation is necessary, a pause of at least half a minute
before starting attempt is repeated.
Marine Gear
The engine is equipped with a reverse-reduction gear. The standard reduction is 2.13:1
for AHEAD and 1.95:1 for REVERSE (but also available as 2.63:1 for special purposes).
The marine gear will need no other attendance than regular change of oil. This to be
carried out after 25 hours of operation, and then every 250 hours or once a year.
Oil quality: "Automatic Transmission Fluid” (ATF).
The oil change is carried out by means of the lubricating
oil bilge pump fitted on the engine.
The oil should be warm when draining.
Refill new oil to the quantity of 0.5 liters through the dipstick hole.
Check oil level on the dipstick.
Don’t forget to close the cock before starting up.
28. Cooling water filling plug
31. Zinc anode
33. Thermostat housing
34. Temperature transmitter
37. Lubricating oil cooler
42. Heat exchanger
43. Cooling water pump
