Doosan G643, Руководство по обслуживанию

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G643 (E) Service Manual Chapter 3. Engine Mechanical System 52
Testing & Adjusting
Adhere to the following warnings when performing
any tests or adjustments while the engine is running:
WARNING
Work carefully around an engine that is running.
Engine parts that are hot, or parts that are
moving, can cause personal injury.
WARNING
Exhaust fumes contain carbon monoxide (CO)
which can cause personal injury or death. Start
and operate the engine in a well ventilated area
only. In an enclosed area, vent the exhaust to
the outside.
This engine has a pressure type cooling system. A
pressure type cooling system gives two advantages.
The first advantage is that the cooling system can
have safe operation at a temperature that is higher
than the normal boiling (steam) point of water. The
second advantage is that this type system prevents
cavitation (the sudden making of low pressure
bubbles in liquids by mechanical forces) in the water
pump. With this type system, it is more difficult for
an air or steam pocket to be made in the cooling
system.
The cause for an engine getting too hot is generally
because regular inspections of the cooling system
were not made. Make a visual inspection of the
cooling system before testing with testing equipment.
Cooling System Visual Inspection
WARNING
Do not loosen the filler cap or pressure cap on a
hot engine. Steam or hot coolant can cause
severe burns
.
1 . After the engine is cool, loosen the filler cap (on a
radiator with a pressure cap, turn it to the first
stop) to let pressure out of the cooling system.
Then remove filler or pressure cap.
2 . Check coolant level in the cooling system.
3 . Look for leaks in the system.
4 . Look for bent radiator fins. Be sure that air flow
through the radiator does not have a restriction.
5 . Inspect the drive belts for the fan.
6 . Check for damage to the fan blades.
7 . Look for air or combustion gas in the cooling
system.
8 . Inspect the filler cap and the surface that seals
the cap. This surface must be clean.
9 . Look for a large amount of dirt in the radiator core
and on the engine.
10 . Check for loose or missing fan shrouds that
cause poor flow of cooling air.
Cooling System Tests
Remember that temperature and pressure work
together. When making a diagnosis of a cooling
system problem, temperature and pressure must
both be checked. Cooling system pressure will have
an effect on cooling system temperatures. For an
example, look at the chart to see the effect of
pressure and height above sea level on the boiling
(steam) point of water.