Instruction to Operate Cummins Engine At High Altitude

by Generator D. Diesel Generator

Don't know how to correctly operate Cummins engine at high altitude? Should the engine idle for a long time before shut-down? In this article, you will learn the detailed steps. No matter it is to shut-down the engine or start the engine, it has the related requirements. Continue reading.

In areas of high altitude, the air pressure drops and weather reducing the air density. This can create problems with start a new diesel generator if it is not accounted air compressor in combustion chamber for ignition. Another factor that gets affected is availability of ambient air to facilitate heat dissipation from the generator. A lot of heat is created during the combustion process and needs to be dissipated into the environment to reduce engine temperature. At high altitudes, due to the low air density, heat dissipation occurs at a much slower, resulting in high engine temperatures for a sustained period of time. The engine remains hot and overheating is a common problem in such cases.

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 [304.8] 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 od 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.

Diesel engines work by compressing air with a piston to create heat necessary to ignite the fuel that is then directly injected into it. In most diesel engines are designed to work with the air density we have at 500 feet or less. For every 1000 feet in elevation the air density decreases 2.9 - 3%. At 3000 feet there is up to 9% less air to compress so less heat is generated. The loss of heat results in incomplete combustion and loss of power. The incomplete combustion also damages exhaust systems and shortens engine life.

In turbo systems the larger engines are able to ram more air into the combustion chamber increasing the air density however; portable generators do not use turbo or super chargers, so portable diesel generators are not able to functioning in high altitude are. It is not considered normal operating conditions and any engine damage would not be covered. It is the same with all diesels however; most other sellers will not tell you this. For higher altitudes you need a super charger or turbo charger. That is only something you find on larger diesel engines. They are compressors that ram more air into the engine to create higher pressures and greater air density.