What is Caterpillar Doing to Reduce White Smoke at Start-Up?

White smoke, which is basically unburned fuel, is often noticed at engine start-up for several reasons. First, fuel is not burned efficiently when the engine runs at idle or at low engine speed without load, which are normal start-up conditions. Cold ambient air temperatures and cold engine coolant temperatures also contribute to inefficient combustion. Another major factor is retarded timing, which means the fuel is injected after the optimum time for complete combustion. (Retarded timing is used to help improve starting capabilities, decrease noise or lower engine emissions.)

Caterpillar has made several improvements to its engines to reduce white smoke at start-up. Various attachments are available to shorten the time it takes for the engine to reach operating temperature by heating the coolant or the inlet air. These include jacket water or block heaters, and inlet air heaters. Attachments vary among different engine models.

Caterpillar has also made iron modifications to help reduce white smoke. Using different pistons to increase the compression ratio or altering the opening and closing of valves can reduce white smoke, too. For example, the 3208 marine engine rated 435 bhp (326 bkW) has a camshaft that closes the inlet valves earlier. This makes start-up more efficient, reducing smoke.

White smoke is typically not as much of a problem with electronically governed engines as it is with mechanically governed engines. This is because fuel injection timing is controlled by software rather than mechanical devices. All Cat electronic engines feature a Cold Start Strategy that is activated when the coolant temperature falls below a certain point. This strategy can advance the fuel injection timing even when the rpm is low, or make the engine run on a portion of the cylinders until the engine is warm. For example, the 3406E marine engine uses only three of the six cylinders during cold mode operation.

Finally, refer to your engine’s operating and maintenance manual for the recommended fuel and lube oil for the ambient conditions in which the vessel operates.


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