Isuzu NHR 4J Series, Workshop Manual

Page: 72 / 406

GENERAL ENGINE MECHANICAL 6A – 5
Hot plug removal (4JG2 only)
1. Insert a 3.0 - 5.0 (0.12 - 0.20.) diameter bar into the
nozzle holder fitting hole unit it makes contact with the
hot plug.
2. Lightly tap the bar with a hammer to drive the hot plug
free.
If the measured value exceeds the limit, the hot plugs
must be replaced.
Combustion chamber inspection (4JG2 only)
1. Remove the carbon adhering to the inside of the
combustion chamber. Take care not to damage the
hot plug fitting positions.
2. Inspect the inside of the combustion chamber, the hot
plug, and the hot plug machined faces for cracking
and other damage.
If cracking or damage is present, the cylinder head
must be replaced.
NOTE:
Be absolutely certain that there are no scratches or
protuberance on the combustion chamber surfaces
which will be in contact with the hot plug after it is
installed. There flaws will prevent the hot plug from
seating correctly.
Hot plug inspection
Inspection the hot plugs for excessive wear and other
damage. Replace the hot plugs if either of these
conditions are discovered.
Hot plug installation (4JG2 only)
1. Align the hot plug knock ball
!
with the cylinder head
groove
"
and tap it temporarily into position with a
plastic hammer.
2. Place an appropriate metal plate
#
thick over the hot
plug upper surface
$
3. Use a press
%
to exert a pressure of 44130 - 53937N
(4500 - 5500 kg/9923 - 12128 lbs.) on the metal plate
covering the hot plug upper surface. This will drive the
hot plug into position.
4. Lightly tap the hot plug heads to make sure that they
are firmly seated.
5. Repeat the procedure Steps 1-4 for the remaining hot
plugs.
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