RickRackstop wrote:
The habit of leaving engines idling for long periods of time is so that they stay warm and ready for instant use. With modern sensors they can cycle them on and off and still maintain enough warmth in the engine. Kim Hotstart is one of the companies that design and build stay warm systems for diesel engines and the basic unit that requires it to be plugged into a shore power system costs about $3000 I think. All diesels used for emergency operations have heating systems designed or at least approved by the manufacturer.
Starting an engine periodically just to keep it warm enough to rapidly pick up load without undue wear or damage is insane. It burns expensive fuel oil and results in unnecessary internal wear. Stationary applications, requiring large sources of emergency electrical power literally within seconds, use relatively small electrical immersion heaters in the oil coolers. A small pump, usually called a "soak back" pump, continuously circulates the oil throughout the engine and especially the turbocharger. Nuclear power plants, as an example, use this technique. The 3,000 to 4,000 HP emergency diesel generators in these applications are able to start, come up to speed, and start picking up significant load in less than 10 seconds. It seems strange locomotive engines would use such a fuel and ultimately maintenance intensive method of accomplishing something similar.