Isuzu NHR 4J Series, Workshop Manual

Page: 87 / 406

6A – 20 GENERAL ENGINE MECHANICAL
TAPPET
Visually inspect the tappet camshaft contact surfaces for
pitting, cracking, and other abnormal conditions. The
tappet must be replaced if any of these conditions are
present.
Refer to the illustration at the left.
!
Normal contact
"
Cracking
#
Pitting
$
Irregular contact
%
Irregular contact
NOTE:
The tappet surfaces are spherical. Do not attempt to
grind them with an oil stone or similar tool in an effort
to repair the tappet. If the tappet is damaged, it must
be replaced.
Tappet Outside Diameter
1. Measure the tappet outside diameter with a
micrometer. If the measured value is less than the
specified limit, the tappet must be replaced.
Tappet Outside Diameter mm (in)
Standard Limit
12.97 - 12.99
(0.510 - 0.511)
12.95 (0.509)
2. Measure the inside diameter tappet on the cylinder
block and calculate the clearance.
If the clearance exceeds the limit, replace tappet
or/and cylinder block.
Tappet and Cylinder Body Clearance mm (in)
Standard Limit
0.03 (0.001) 0.10 (0.004)
REASSEMBLY
9. Tappet
1) Apply a coat of engine oil to the tappet 1 and the
cylinder body tappet insert holes 2.
2) Locate the position mark applies at disassembly (if the
tappet is to be reused).
NOTE:
The tappet must be installed before the camshaft.
6A-20-1.tif
6A-20-2.tif
6A-20-3.tif
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