OK, I know how diesel engines work, but I’m not quite sure why it takes longer for them to warm up – both for starting and for putting into gear – than gasoline engines.
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The fundamental difference between diesel and gasoline, in the context of your question, is that gasoline is a hell of a lot easier to burn — all you need is a spark, graciously provided by your spark plug.
Diesel fuel won’t ignite with a spark; it has to be heated and compressed by the engine cylinders. If the engine is cold, that saps heat that could be contributing to igniting the fuel. So, you have to let the engine warm up so that it can channel more heat into actually combusting the diesel.
Everything else being equal, a diesel engine also will be hevier, because pressure on the pistons was muth higher. The reinforcement to cope with these pressures is extra metal that needs to be warmed.
I was driving a diesel truck from Illinois down to Austin TX.
My alternator gave out after Dallas and we had just enough daylight to make it to Austin.
Two pickup trucks gave me a jump and we made the run to Austin.
With the alternator dead in August, we rolled down the windows and hoped for the best.
The radio quit and thin the instrument panel went dead.
We ran the last 3 1/2 hours just squeezing diesel in the ‘92 F-250.
No spark required…
We replaced the alternator and came home with all the electric amenities working.
Diesel engines need to combust their fuel upon compression of the piston.
Cold temperatures means this doesn’t happen, or at least not as efficiently.
Gasoline engines don’t do this. Instead, they fire the spark plugs every single time to ignite the fuel.
If gasoline engines get too hot, or use unadulterated fuel, they will start dieseling (combusting on compression) which causes engine knock in gasoline engines.
Leaded gasoline was invented to fix this. Adding tetra-ethyl lead prevents the gasoline from igniting on compression. 10% ethanol does the same thing.
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