Onan RDJE User Manual

2.
3.
4.
*
Using a feeler gauge, check clearance between
rocker arm and valve (see Figure 51). Increase or
reduce clearance until proper gap is established;
adjust with lock nut which secures rocker arm to
cylinder head.
Repeat Step
1 for number 2 cylinder.
Repeat Step 2 for number 2 cylinder.
Compression readings will deviate considerably from
the above readings because of differences in crank-
ing speed, altitude and ambient temperature con-
ditions. Therefore the specification is given only as a
guide. The best indication of leakage is the pressure
difference between cylinders or a compression
in-
crease when oil is added to the cylinder.
Disassembly:
RDJEA Engines
To adjust valve clearance on RDJEA engines,
proceed as follows:
1. Rotate flywheel clockwise until cylinder number 1
is up on a compression stroke and the TC mark on
the flywheel lines up with the timing pointer on
the gear cover, then turn 10 to
45" past TC to be
sure lifter moves off ramp of cam. Adjust bbth
valves, intake and exhaust, to 0.017 inch
(0.43
mm).
In this position, both valves will be closed and the rocker arm is
free to move slightly indicating maximum clearance.
2. Using a feeler gauge. check clearance between
rocker arm and valve (see Figure 51). Increase
or
reduce clearance until proper gap is established;
adjust with lock nut which secures rocker arm to
cylinder head, Figure 51.
3. To adjust valve clearance for number 2 cylinder,
turn flywheel in aclockwisedirection 180degrees
(1/2 revolution) from position used in Step
1. The
flywheel position should be between 10 degrees
and 45 degrees past the bottom center (BC).
4. After timing number 2 cylinder, adjust valve
clearance according to Step 2.
Testing:
The cylinder compression test can be used to deter-
mine the condition of valves, pistons, piston rings and
cylinders.
To check compression, run the engine until
thoroughly warm. Stop engine and remove all injec-
tion nozzles. Insert the compression gauge in one
nozzle hole. Crank the engine and note the reading.
To check for piston blow-by, squirt a small amount of
SAE 50 oil into the cylinder and repeat the check. An
increase
in compression with oil in the cylinder
indicates piston blow-by.
Keep rocker arms, rocker arm nuts, push rods and tappetsin order,
so they go back in the same valve train position.
1. Remove rocker box cover, fuel nozzles and
connecting
oil lines to cylinder heads.
2. Remove intake and exhaust manifold.
3. Remove cap screws holding each cylinder head
to cylinder block.
4. Remove each head. If it sticks, rap it sharply with a
soft hammer. Do not use a pry.
5. Remove rocker arms and push rods.
6. Using avalve spring compressor, disassemble the
valve assemblies.
Repair:
Thoroughly clean all components of the cylinder
head assemblies. Remove all the carbon deposits
from the intake and exhaust ports and clean all gasket
surfaces.
Valves: Remove all carbon and check each valve for
burning, pitting,
or a warped stem. Refinish valves
that are slightly pitted
or burned on an accurate valve
grinder. Refinish intake valves to a 42 degree angle
and exhaust valves to a 45 degree angle. If they are
badly pitted
or have a thin edge when refacing,
replace them.
Check refinished valves for a tight seat to the valve
seat with an air-pressure-type, testing tool
or by
applying Prussian Blue on the valve face and rotating
it against the seat.
Valve Guides: Check valve guide to valve clearance.
See the
DIMENSIONS AND CLEARANCES section. If
the proper clearances cannot be obtained by replac-
ing the valves, replace the valve guides. Drive the old
valve guides into the valve chambers. Drive new
guides in until they protrude 11/32 inch (8.731 mm)
from the rocker box side of the head. Ream the new
valve guide to obtain the proper clearance.
Valve Seats: If thevalve seats are pitted, refinish them.
Using conventional seat-grinding equipment, reface
Compression of a standard new engine cranking at each seat to a45degreeangleand aseatwidthof 3/64
about 300 rpm is about 350-4OOpsi (2415 to inch to 1/16 inch (1.191 to 1.588 mm) You should be
2760 kPa). Compression should be fairly uniform, able to reface each seat several times before it
normally with less than 10 psi
(69 kPa) difference
becomes necessary to replace
it.
between the highest and lowest cylinder, taken at the
same cranking rpm. Excessively high readings
in- If the valve seats are loose or cannot be refaced,
dicate carboned combustion chambers.
replace them.
44

Onan RDJE Specifications

General

Brand	Onan
Model	RDJE
Category	Engine
Language	English