Onan DJA Series User Manual

COOLING SYSTEM
To remove heat produced during operation, engines
use a pressure air-cooling system. Blades on the
engine flywheel draw air in the front of the engine
housing, force the air past the cylinder and out the
right side of the engine. See Figure 8.
From the engine outlet, air can be ducted out of the
area. To improve engine temperature control, an
optional shutter assembly can be installed on the air
outlet. See Figure 9.
MAINTENANCE
With a properly installed engine, maintenance should
consist of cleaning the engine cooling area (fins on
cylinderblock and cylinderhead) at regular intervals,
normally every 1000 hours but more often under dirty
operating conditions.
OVERHEATING
This is sometimes difficult to discover in an air-cooled
engine. However, the first sign is usually engine
losing speed momentarily or low engine power. This
happens before the engine seizes and results in a
scored piston.
The most probable causes of overheating are dirty
cooling surfaces, operating without the engine air
housing, poor air circulation, improper lubrication,
wrong injection timing and engine overload.
CAUTION
The air housing including the door must be on
when operating the engine. Overtteating and
permanent damage could result from as little as one minute of
operation without it.
Common installation problems leading to over-
heating are as follows: x
1. Installation with duct size too small so air flow is
insufficient.
2. Installation in small room with no ducts and
insufficient air ventilation in the room.
3. Installation of air inlet and outlet ducts so air
outlet feeds back to the inlet.
AIR SHUTTER (Optional)
The optional air shutter assembly is mounted at the
engine air outlet, on the right side of fhe cylinder
shroud. A thermostatic element (Figure 10) controls
the shutters so they close and limit air flow when the
air temperature reaches 120°F. The power element
plunger begins to move outward, opening the
shutters until they are completely open by 140° F.
Shutter opening temperature is not adjustable, but to
assure complete opening, the powerelement plunger
must contact the shutter roll pin at room temperature.
To adjust this, loosen the power element mounting
screws and slide the assembly until it touches the roll
pin with the shutter.closed.
BLOWER
HOUSING
ACCESS
DOOR
AIR IN
BLOWER
WHEEL
AIR DUCT
- AND
SHUTTER
FIGURE 8. COOLING AIR FLOW
FIGURE 9. AIR DUCT AND SHUTTER
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Onan DJA Series Specifications

General

Brand	Onan
Model	DJA Series
Category	Engine
Language	English