138
Cooling fan speed B10B
40
50
60
70
80
0
10
20
30
40
50
60
70
80
90
100
Air temperature (
°
C)
Engage degree
Viscofan
[%]
Checking
Expensive testing equipment is required to do a
complete check on the thermostat-regulated cool-
ing fan. One of the reasons for this is that it is diffi-
cult to measure the air temperature round the bi-
metal plates. If the cooling fan does not seem to
work, there is a simple way in which to check the
fan.
Fan speed and drive shaft speed can be measured
with an optical tachometer that works with reflec-
tion tape. A piece of this tape is stuck on a fan blade
and another piece next to the fan drive shaft. Start
the check with a cold engine and an ambient tem-
perature of max. 25
°
C. Then run the engine to
about 2000 r/min. If fan speed increases at temper-
atures below 25
°
C, then there is something wrong
with fan control mechanism.
The fan control mechanism is functioning properly
if the degree of engagement is within the gray-
marked sector in the diagram below.
Note, however, that it is fully normal if the fan en-
gages at full speed to begin with. Wait, therefore,
until the fan speed has stabilized before checking.
Engine speed = 2000 r/min
Pulley with fan journalling = 1.05x2000 = 2100 r/min
Warning!
Do not go near the fan when it is rotating.
Содержание DH10A 245
Страница 1: ...Service Manual Buses Section 2 20 27 Engine DH10A 245 285 345 350 360 TP 16031 1 ...
Страница 31: ...30 Adjust in the supports on the lift unit as shown in the pictures below ...
Страница 59: ...58 Cylinder block crank mechanism ...
Страница 162: ...Volvo Bus Corporation TP 16031 1 English 2500 06 97 Printed in Sweden by Novum Grafiska AB 97 24296 Göteborg Sweden ...