restarting a engine vs turning the truck off

How do you re-start an engine wiihtout first turning it off?

Now for restarting an engine vs leaving it running I have heard the break even point is about 40 seconds.

 

Avg. 3/4 to 1 Gallon /Hour to idle on low RPM = it will cost you or the company 24x$3.75/Gal=$90 every 24 hrs Idle if you are buying retail fuel@ $3.75/Gallon

 

Detroit 12.7 pre-egr in my truck uses 1/2 gal hour.
I have no proof but have always heard that 3 mins is the break even point.

this would be a great one to send to "Myth Busters".
They put to bed the tail gate up vs down myth, and also the A/c on vs windows down. good stuff.

 

Mythbusters had one recently about that. One thing they done was extending mpg's by shutting down engines at red lights. But you have to take into account starter/solenoid wear and tear. I always used a 3 minute rule. When you come off the road it takes 3 minutes for your cylinder temperature to settle. Repeated shutdowns I would use common sense and think about that starter.

 

In a diesel engine properly allowing the turbo to cool down is a more important factor than a bit of fuel used for a couple of minutes at a traffic light. Especially with the much more expensive variable vane turbos on the newer engines!

 

I shut mine off with out giving any turbo cool time. Turbo is still great after 927,000 miles. (engine is still original to, no inframe, although it needs one soon)

Strictly fuel, The break even is 15 seconds. They use more fuel to start, but not for very long at all. I've verified this looking at a graph from my scan gauge.

 

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