Section 2
SPECIAL OPERATING CONDITIONS
Precautions to be observed when operating at
high altitudes and low ambient temperatures.
Because of low atmospheric pressure which
reduces the oxygen content at high altitudes it is
necessary to make certain adjustments in the fuel
injection pump output to prevent black smoke
caused by unburnt fuel emitting from the engine.
Similarly the lubrication, fuel and the cooling
system have to be properly attend to when
S-3.8-G engine is operated at very low ambient
temperatures.
We are giving below special instructions to be
followed while operating Cummins Diesel
Engines at high altitudes and low ambient
temperature.
1) HIGH ALTITUDE OPERATION
Fuel System
The engine output decreases due to reduction in
the atmospheric pressure and density. To ensure
an optimum operation of the engine at these
conditions, it is necessary to reduce fuel supply
for the range of altitudes are given below. This
is necessary since devices which will correct fuel
supply during operation at varying altitudes are not
available.
For Alternating in low and high altitudes up to
approx. 2000 meters, no changes of the setting
are necessary in general.
For operation above 2000 meters, injection pumps
which inject a reduced quantity of fuel as
compared to the standard pump are required.
In injection pumps installed as standard
equipment, the quantity of fuel injected can be
reduced by loosening the lock nut & turning the
full-load stop screw for the control rod clockwise
for RSV pumps.The adjustment should be made
on an injection pump test stand. Turning the
stop screw
clockwise or anti-clockwise direction as the case
may be, results in a reduction of quantity of fuel
injection, 1/4 turn correspond to approx. 7% of the
total quantity injected.
For smoke-free operation of the diesel altitude, the
quantity above 2000 meters altitude, the quantity
injected should be reduced by about 20%
(corresponding to 3/4 turn of the stop screw)
Mark injection pump by the letter "z' behind the
pump designation after the work was carried out.
The adjustment to the fuel injection pump should
be carried out at authorised MICO dealers
workshops.
2) LOW TEMPERATURE OPERATION
Lubrication System
The lubrication oils for engine, are required to be
of lower viscosity.
Recommendations for the same are as under :
The recommended types of engine oils and the
range of ambient temperatures at which these can
be used are given in the following table.
Ambient temperature
in deg. C
Engine oil
grade
-10 and above
-20 to 0
-10 and Below
SAE 15W40
SAE 10W30
SAE 5W20
These oils should confirm to SAE API CF4+
specification.
Cooling System
Certain precautions have to be taken to enable
the cooling system to function properly at very low
ambient temperatures. To attain the recommended
working temperature of the engine faster, it is
necessary to use a radiator blind.
Use the antifreeze and water to 50:50 proportion.
Workshop Manual
S3.8 Engine
A030K288 (Issue 2)
01-2010
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