57
PERIODICAL INSPECTION AND MAINTENANCE.
7/71, 12/56
Fuel System Air Bleeding
The entry of air into the fuel system will cause difficult engine starting
or engine malfunction.
When carrying out service procedures such as emptying the fuel
tank, draining the filter/separator, and changing the fuel filter element,
be sure to bleed air from the fuel system.
Air bleeding method:
’At fuel filter’
Loosen air bleed screw D (fig. 16).
Operate supply pump priming lever E until fuel flow is free of
bubbles.
Tighten bleed screw D, continue operating priming lever until
pumping action is not felt.
Start engine and check for leaks
’At injection pump’
Fig. 17
Slightly loosen fuel return line connector B (fig 17).
Operate supply pump priming lever E until fuel flow is free of
bubbles.
Tighten return line connector to 27Nm.
NOTE:
Air can also be bled by use of the primer pump facility in the
filter/separator assembly.
By unscrewing the plastic primer pump head ‘A’ and stroking it up and
down, any air bubbles in the system will be purged back to the fuel tank.
When this has been completed, the pump head must be screwed back
into the filter/separator assembly
Start the engine and visually check the fuel system for leaks.
Governor Control Seals
As the governor is precisely adjusted, most of the controls are
sealed, please do not break them. Should any adjustment be
necessary, contact your local Doosan branch or distributor.
NOTE: Doosan will not accept any warranty claim on an engine
with broken governor seals.
AIR INTAKE SYSTEM
Air cleaner
Engine performance and life vary with the air intake conditions.
A dirty air cleaner element reduces the amount of intake air, causing
reduced engine output and possible engine damage.
Also, a damaged element leads to abrasion of cylinders and valves,
resulting in increased oil consumption, reduced output and shortened
engine life.
The filter element should be changed at 500 hours or 6 months,
whichever comes first, or sooner if the restriction indicator shows red.
See below.
Fig. 18
A Normal
B Clogged
C Indicator
D Red signal
Air cleaner with dust indicator
This indicator is attached to the air cleaner. When the air cleaner
element is clogged, air intake resistance becomes greater and the dust
indicator signal turns to red indicating the element needs to be
changed.
When the signal turns to red, replace the element. Then press the
dust indicator button to reset the indication.
ENGINE ELECTRICAL
The Doosan engines uses a 12 volt system and a negative grounding
for the electrical system.
Battery Servicing
Battery terminal connections
Check the battery cable connections for looseness or corrosion.
Poor cable connections will result in difficult engine starting or
insufficient battery charge.
The battery cables must be tightened securely.
Never reverse “+” and “−” terminals when reconnecting cables
after removal. Even a short period of reverse connection will
damage the electrical parts.
Cleaning of Battery
When the battery terminals are fouled clean them with clean tepid water
and wipe with a dry cloth to remove the water. Apply a light coat of
vaseline or a grease.
Alternator Servicing
The polarity of the alternator is negative (−) grounding type.
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