Onan DJA Series User Manual

6. Tighten the cap screws to the specified torque.
7. Crank the engine over by hand to see that the
bearings are free.
8. Install the oil base with a new gasket.
9. Install the cylinder head using an even bolt
tightening sequence and specified torque.
10. Replace oil.
CAMSHAFT
The camshaft is a one-piece machine casting, driven
through gears by the crankshaft. It rides on sleeve
bearings pressed into the crankcase.
In addition to providing a means of opening and closing
the valves, the camshaft operates the injection pump
and fuel transfer pump.
Removal:
1. Remove the rocker arms and push rods from the
valve chambers.
2. Remove the injection pump and fuel transfer pump
from the engine.
3. Remove the crankshaft gear retaining washer by
removing the lock ring on the crankshaft.
4. Lay the engine on side to avoid dropping tappets
and remove the camshaft assembly as a group. If
necessary, pry it out with a screwdriver between
the camshaft gear and crankcase..
5. Remove the valve tappets. These can be removed
only from the camshaft end of the push rod holes.
Repair: If a lobe has become slightly scored, dress it
smooth with a fine stone. If the camshaft is badly worn
or scored, replace it. After installing a new camshaft,
retime the injection pump to the engine.
Camshaft Gear: This gear is & pressed fit on the cam-
shaft and drives it at 1/2 the crankshaft speed. To
remove the goar, use a hollcw tool or pipe that will
fit inside the gear bore and over the center pin. Press
the camshaft out of the ' gear bore. Be careful not to
damage the cf.'nter pin.
Camshaft Bearings: The camshaft bearings should be
replaced if the clearance to the camshaft is greater
than specified, the bearings show cracks, breaks, burrs,
excessive wear, or other defects. The camshaft to
bearing clearance should be 0.0012-inch to 0.0037-inch.
To check the rear bearing, remove the expansion plug
at the rear of the crankcase.
Press new bearings into place (Figure 47). Press the
rear bearing flush with the bottom of the expansion
plug recess. Press the front bearing in flush with the
crankcase front surface so the oil passages are aligned.
Do not attempt to ream the bearings, they are a preci-
sion type. After the rear bearing is installed, insert a
new expansion plug in the recess, using sealing com-
pound, and expand it into place with sharp blows at
its center.
Installation, Camshaft Assembly:
1. Install the key and press the camshaft gear on its
shaft.
2. Install the governor components.
3. Slide the thrust washer onto the shaft.
4. Lay the engine on side or end and insert the push
rod tappets.
5. Install the camshaft assembly in the engine. Align
the timing marks on the camshaft gear and crank-
shaft gear. See Figures 48 and 49.
6. Replace the push rods and fuel transfer pump.
7. When the engine is reassembled, install the injec-
tion pump following the steps for Injection Pump
•Installation in the FUEL SYSTEM Section. This
step is critical.
CRANKSHAFt
These engines use a counter-balanced, ductile iron
crankshaft. To increase the shafts fatigue durability,
all crankpin fillets are shot-peened during manufactur-
ing. The crankshafts ride on two lead-bronze bearings,
the front one housed in the crankcase and the rear one
in the bearing plate.
PRESS BEARING
FLUSH WITH
BOTTOM OF
RECESS
[4- REAR
BEARING
•-PRESS BEARING
FLUSH WITH
FRONT CRANK-
CASE SURFACE
CENTER
BEARING
ALIGN OIL
HOLES.,
FIGURE 47. CAMSHAFT BEARINGS
41

Onan DJA Series Specifications

General

Brand	Onan
Model	DJA Series
Category	Engine
Language	English