<VV> Curious Question - idling

[Dale Dewald]

At 06:55 PM 10/20/04 -0400, Garland wrote:
>When driving my corvair and need to stop,  if I am going to be out of  car
>less then 5 min. I leave car runing. I feel that it is better to idle 
>and  cool
>down than restarting hot car. Does anyone have an opinion on what is  best.

With a gasoline engine at operating temperature it makes no sense to idle 
at a pause in your trip for more than 30 seconds (about the wait for a 
traffic light) without shutting down.  For diesels you may extend that time 
to 1 minute.  Any more idling only wastes fuel.  Other circumstances may 
warrant longer idling, such as; engine not yet up to normal operating 
temperature, low outside ambient temperatures (< 30 F) and you need to 
maintain heater/defroster function, or recent high speed/high load 
operation (engine higher than normal operating temperature).  If your 
engine will not start after sitting for 5 minutes after shutting it down 
from normal operating temperature then something is wrong with the fuel, 
ignition, or cooling systems.

Watch what UPS drivers do...they have been taught to shut off the engines 
of their delivery trucks 20 feet away (or more) from their destination, 
then start and get under way in less than 5 seconds.  This apparently has 
no detrimental effect on the vehicle, but it does save fuel.

The only vehicle I idle for any period of time to allow for cooling is my 
Dodge truck with its Cummins diesel engine.  I try to let the exhaust 
temperature gauge (turbocharger) cool below 350F before shutting down so as 
to not cook the oil in the turbocharger bearings.  Usually this ends up 
being less than a minute.

Dale Dewald
Hancock, (UP) MI