Torque Limitation For Overheat Protection - Yanmar BY Series Service Manual

Engine Faults and Torque Limitations
Torque Reduction Chart Based on Intake Air Temperature
The intake air temperature will limit the torque at 3000 rpm if the air temperature is increasing.
Engine speed
Torque
Engine
100% (normal operation)
90%
80%
Engine
100% (normal operation)
90%
80%
Torque Limitation for Overheat
Protection
In the case of this limitation there are two possible
situations:
If an electronic fault occurs, it will be displayed on
the display-alarm and a P-Code is saved in the
system. These codes can be read with a diagnostic
tester. A substitute value (fixed value until fault
disappears) is activated (coolant temp=110,
fuel temp=90) and a torque reduction occurs. In this
case, the coolant temperature is also limited by the
torque limit which is described in Torque Limitation
for Failed Sensors on page 13-3. The substitute
value of the fuel temperature is fixed at 90°C and
that sets a limitation of approximately 75% from the
maximum torque (Figure 13-1).
If the coolant temperature is over 108°C, an audible
alarm sounds and engine overheat is displayed on
the instrument panel display. At 120°C the torque
limitation is 30% (Figure 13-2). If the fuel
temperature is too high (over 90°C) this limitation is
also active for the overheat prevention as shown in
Figure 13-1. From 100 to 140°C the torque limit is
about 40% of the maximum torque. In this case
there is not an alarm on the instrument panel
display. In both cases, no P-Code appears.
BY Service Manual
2000 rpm
Intake air
Torque [N·m]
temperature [°C]
4BY150
295
265
240 100-130
6BY220
450
405
360 100-130
TROUBLESHOOTING
Torque [N·m]
30-50 315
60-90 285
250
30-50 450
60-90 405
360
Figure 13-1
Figure 13-2
2000 rpm
Intake air
temperature [°C]
4BY180
30-50
60-90
100-130
6BY260
30-50
60-90
100-130
13-5