Onan DJA Series User Manual

COOLING SYSTEM
To remove heat produced during operation, engines use a
pressure air cooling system. Blades on the engine fly-wheel
draw air in the front of the engine housing, force the air
past the cylinder and out the right side of the engine.
Caution: The air housing including the door must be on
when operating the engine. Overheating and permanent
damage could result Irom as little as one minute oi oper-
ation without it.
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.
MAINTENANCE
With a properly installed engine, maintenance should con-
sist of cleaning the engine cooling area (fins on cylinder
block and cylinder head) at regular intervals, normally every
1,000-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 be-
fore 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 over-loaded.
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 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 die right side of the cylinder shroud. A thermo-
static element (Fig. 5-3) controls the shutters so they close
and limit air flow when the engine is cold. When the air
temperature reaches 120
o
F the power element plunger be-
gins to move outward, opening the shutters until they are
completely open by 140
o
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,
BLOWER
HOUSING
AIR IN
BLOWER
WHEEL
FIG. 5-1
AIR DUCT
AND
SHUTTER
FIG. 5-2
io

Onan DJA Series Specifications

General

Brand	Onan
Model	DJA Series
Category	Engine
Language	English