Yanmar 4TNE98, Service Manual

Page: 162 / 246

4TNV98 & 4TNE98 Diesel Engine Section 4. Fuel System 160
NOTE: The TDC (Top Dead Center) mark can be
identified by the cylinder numbers stamped near the
TDC mark on the flywheel.
If you are uncertain as to the timing degree
designation of the timing marks on the flywheel
timing grid, you can determine the timing degree
designation by measuring the timing grid.
• First measure the distance between two of the
“longer” marks on the timing grid. (They are 5°
apart.) Then measure the distance from the
TDC mark to the first “longer” mark on the
timing grid. Divide that measurement by the
distance between the two “longer” marks. The
resulting answer will tell you how many
degrees there are between the TDC mark and
the first “longer” mark.
• EXAMPLE: If the distance between the two
“longer” marks is approximately 2.0 cm and
the distance from the TDC mark is
approximately 4.0cm, the answer is
approximately 2. This indicates there is 10°
(2x5°) between the TDC mark and the first
“longer” mark on the timing grid. That means
the first “longer” mark on the timing grid
indicates 10° BTDC, the second “longer” mark
indicates 15° BTDC and the third timing mark
indicates 20° BTDC. If the answer is 3, that
indicates there is 15° (3x15°) between the
TDC mark and the first “longer” mark and that
the first “longer” mark indicates 15° BTDC
with the second and third “longer” marks
indicating 20° BTDC and 25° BTDC
respectively.
8. Highlight the timing reference mark (Figure 7-41,
(2)) on the flywheel housing or engine back plate
(Figure 7-42, (2)) . Highlight the TDC (Top Dead
Center) mark (Figure 7-41, (1)) on the flywheel.
9. Highlight the target timing mark (Figure 7-42,
(1)) on the flywheel as calculated in Determining
the Fuel Injection Timing Specification on page
141.
Figure 7-41
Figure 7-42