PRODUCT OVERVIEW
JH Series Operation Manual
17
FUNCTION OF MAJOR COMPONENTS
Name of Component
Function
Fuel Filter
The fuel filter removes contaminants and sediments from the diesel fuel. Periodic replacement
of the fuel filter is necessary.
See PERIODIC MAINTENANCE SCHEDULE on page 113
for
the replacement frequency.
Fuel pre-filter
(Water separator)
The water separator removes contaminants, sediment and water from diesel fuel going to the
fuel filter. This is a required component of the fuel system and is standard equipment with
every engine. The water separator is installed between the fuel tank and the fuel filter.
Periodically drain the water from the water separator using the drain cock at the bottom of the
separator and replace the filter element.
Fuel Priming Pump
This is a manual fuel pump. Pushing the knob on the top of the fuel pre-filter feeds the fuel.
This pump is also used to bleed air from the fuel system.
Engine Oil Filler Port
Filler port for engine oil.
Engine Oil Filter
Filters fine metal fragments and carbon from the engine oil. Filtered engine oil is distributed to
the engine’s moving parts. The filter is a cartridge type and the element should be replaced
periodically.
See Changing the Engine Oil and Replacing the Engine Oil Filter Element on
.
Marine Gear Filler Port
Filler port for marine gear lube oil. Located on top of the marine gear case.
Cooling System
There are two cooling systems: closed cooling with coolant and seawater. The engine is
cooled by the closed cooling circuit. The closed circuit is cooled by seawater using a heat
exchanger. The seawater also cools the marine gear oil and intake air (depending on model)
through the cooler(s) in an open circuit.
Coolant pump
The centrifugal water pump circulates coolant inside the engine. The circulating pump is
driven by a V-ribbed belt.
Seawater Pump
Pumps seawater from outside vessel to the engine. The seawater pump is gear-driven and
has a replaceable rubber impeller. Do not operate it without seawater, as this will damage the
impeller.
Reservoir
The pressure valve in the filler cap releases vapor and hot water overflow to the reservoir.
When the engine stops and the coolant cools, the pressure in coolant tank drops. The filler
cap vacuum valve then opens to send water back from the reservoir. This minimizes coolant
consumption. The closed cooling system coolant level can easily be checked and refilled in
this tank.
Oil Cooler - Engine
A heat exchanger that cools high temperature engine oil using coolant.
Oil Cooler - Marine Gear
(Optional)
This heat exchanger cools the marine gear (KMH4A) oil using seawater.
Turbocharger (if equipped)
The turbocharger pressurizes the air coming into the engine. It is driven by a turbine that is
energized by exhaust gases.
Air cooler (if equipped)
This heat exchanger cools the pressurized charging air from the turbocharger with seawater
to increase the charging air quantity.
Intake Silencer (Air Cleaner)
The intake silencer guards against dirt in the air and reduces the noise of air intake.
Nameplates
Nameplates are provided on the engine and the marine gear and have the model, serial
number and other data.
Starter
Starter motor for the engine. Powered by the battery.
Alternator
Driven by belt and generates electricity and charges the battery.
Engine Oil Dipstick
Gauge stick for checking the engine oil level.
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