What could happen if someone doesn’t let an engine warm up?
In: Engineering
It used to be the case that you’d manually adjust the AFR (air fuel ratio) of the engine when starting it with the choke during a cold day, and then let it warm up so that it could idle unsupported. when it first started, it wouldn’t be able to self-sustain without using the choke. after it was warm you could drive. nowadays a computer controls the AFR and automatically adjusts it according to tempurature.
the other part of it is oil circulation, which is something that still makes me cringe. Watching someone start an engine and immediately start driving it. The oil pump will not have sufficient pressure to lubricate the engine properly for at least a couple of seconds, as oil falls back into the sump after a short while of the engine being off.
When i start a modern vehicle, i let the engine run for at least 10 seconds before moving. Normally i just start the engine, then get my gloves and helmet on. this provides a convenient time measure, enough for oil to circulate.
In general, engines just like to be at their operating tempurature. their parts are machined to the correct tolerances for a given tempurature. for example the piston rings are set to provide a good seal at around 150-250 degrees, so when they’re dead cold, they’re slightly too small and don’t provide a good fit.
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