What happens if you turn the ignition off when coasting in gear?
I know some young people may be puzzled, but this concerns cars with manual transmission and a key that you turn.
I was wondering what exactly would happen to the engine if I switched off the ignition while coasting in gear? Is that something harmful or could it be done without worrying?
I wouldn’t do it on the road, but as a thought experiment, I find this interesting. So I reckon the alternator, oil and water pumps would keep turning, there would just be no spark in a petrol car. I’m not sure what would happen in a diesel. Any thoughts on this?
Comments
I’m not totally sure. But it would just die as if you stalled car while standing. You would experience huge engine braking for sure tho. I also think that in newer cars it’s not possible to turn ignition off while in high gear
Why do you think the engine braking effect would increase?
I’m a young people but I may have a somewhat answer to your question. And that answer would be, I’m pretty sure it doesn’t hurt anything. But do I do it? No. I think that’s the same effect as when people with autos switch the car off in “D” and the car just shutters a little bit. When me and my uncle used to go hunting, he did it all the time. It bothers me and I don’t do it but if I had to make an educated guess I’d say no it doesn’t hurt anything because it kills the engine and from there on you’re just rolling… Now what I would recommend if you do that is to not leave it in gear as you coast, go ahead and engage the clutch and drop into neutral so that they’re is a smaller possibility of transmission damage
Would you lose power steering or ABS though?
I can imagine there being engine damage if you slow down below idle engine RPM. But what transmission damage could there possibly be?
I’d assume the compression of the engine will brake you to a halt, but your steering may also lock when you turn the car off so for god’s sake - don’t try it.
Yeah, I’ve had the misfortune of that happening to me on the street, when one of my injectors failed. Not great, to say the least. But for this question, I’m only interested in the powertrain in particular. Would I be wrong to assume that e.g. when coasting in 3rd gear at 2000 RPM and shutting off the ignition, everything would be fine until the engine drops to let’s say 1000 RPM, at which point I would just put it in neutral or fire it back up again?