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 option-
al 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
cylinder block and cylinder head) 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.
The air housing including the door
must be on when operating the engine.
Overheating 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:
1. Installation with duct size too small so air flow
is insufficient.
2. Installation in small room with no ducts and insuf-
ficient air ventilation in the room.
3. Installation of air inlet and outlet ducts so air out-
let 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 the cylinder
shroud. A thermostatic element (Figure 10) controls the
shutters so they close and limit air flow when the
air temperature reaches 120
0
F. The power element
plunger begins to move outward, opening the shutters
until they are completely open by 140
0
F.
Shutter opening temperature is not adjustable, but to
assure complete opening, the power element 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
14

Onan DJA Series Specifications

General

Brand	Onan
Model	DJA Series
Category	Engine
Language	English