Workshop Manual S3.8 Engine A030K288 (Issue 2) 01-2010 Section 2 SPECIAL OPERATING CONDITIONS Precautions to be observed when operating at high altitudes and low ambient temperatures. 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. 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.
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) 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. 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. We are giving below special instructions to be followed while operating Cummins Diesel Engines at high altitudes and low ambient temperature.
2) LOW TEMPERATURE OPERATION 1) HIGH ALTITUDE OPERATION Lubrication System Fuel System The lubrication oils for engine, are required to be of lower viscosity. 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. 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.
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. These oils should confirm to SAE API CF4+ specification. Cooling System 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 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. 15 Ambient temperature in deg. C Engine oil grade -10 and above -20 to 0 -10 and Below SAE 15W40 SAE 10W30 SAE 5W20