How to Operate Cummins Engine At High Altitude

This article will show you how to operate Cummins engine at high altitude.

High Altitude Operation

Some engines, lose horsepower when they are operated at high altitude because the air is too thin to burn as much fuel as at sea level. This loss is about 3 percent for each 1000 ft [304.8m]of altitude above sea level. Operate the engine using a lower power requirement at high altitude to prevent smoke and over-fueling.

Power Take-Off Application With PT(type G) VS Fuel Pump

The VS fuel pump governor lever is used to change the standard governed speed of the engine from rated speed to an intermediate power take-off speed.

When changing from the standard speed range to the power take-off speed with the engine idling on standard throttle, operate as follow:

1. Place the VS speed control lever in the operating position.

2. Lock the standard throttle in the full-open position.

3. Engage the power take-off.

To return to standard throttle.

1. Disengage the power take-off.

2. Return the standard throttle to the idle position.

3. Lock the VS speed control lever in the maximum speed position.

Engine Shut-Down

Idle Engine A Few Minutes Before Shut-Down

It is important to idle engine 3 to 5 minutes before shutting it down to allow the lubricating oil and water to carry heat away from the combustion chamber, bearings, shafts, etc. this is especially important with turbocharged engines.

The turbocharger contains bearings and seals that are subject to the high beat of combustion exhaust gases. While the engine is running, this heat is carried away by oil circulation, but if the engine is stopped suddenly, the turbocharger temperature may rise as much as 100°F [38°C]. The results of the extreme heat may be seized bearings or loose oil seals.

Do Not Idle Engine for Excessively Long Periods

Long periods of idling are not good for an engine because the combustion chamber temperatures drop so low the fuel may not burn completely. This will cause carbon to clog the injector spray holes and piston rings and may result in stuck valves.

If the engine coolant temperature becomes too low, raw fuel will wash the lubrication oil off the cylinder walls and dilute the crankcase oil so all moving parts of the engine will suffer from poor lubrication.

If the engine is not being used, shut it down.

Turn Switch to “Off” Position to Shut Down the Engine

The engine can be shut down completely by turning off the switch on installations equipped with an electric shut-down valve, or by turning the manual shut-down valve knob. Turning off the switch which controls the electric shut-down valve stops the engine unless the override button on the shut-down valve has been locked in the open position. If the manual override on the electric shut-down valve is being used, turn the button fully counterclockwise to stop the engine. Refer to “Normal Starting Procedure”. The valve cannot be reopened by the switch until after the engine comes to a complete stop, unless a rapid restart valve is installed.

Caution: Never leave the switch key or the override button in the valve open or in the run position when the engine is not running. With overhead tanks this would allow fuel to drain into the cylinders, causing a hydraulic lock.

Stop the Engine Immediately If Any Parts Fail

Practically all failures give some warning to the operator before the parts fail and ruin the engine. Many engines are saved because alert operators heed warning signs (sudden drop in oil pressure, unusual noises, etc) and immediately shut down the engine.

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