What happens if I turn my car off at high speed and turn it back on? Can I break something?

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What happens if I turn my car off at high speed and turn it back on? Can I break something?

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14 Answers

Anonymous 0 Comments

It depends on the transmission type; basically the engine is engaged with the transmission and if you lose power and spin from the engine, the wheels will feel a sudden torque to stop turning too. So you could lose control and/or break the transmission.

You’ll also lose power steering and power brakes, so loss of control is quite possible.

Anonymous 0 Comments

My dad did this driving down a hill because he heard it’s more economical. He’s also elderly. Called to tell me that he regretted it and would not do it again

Anonymous 0 Comments

what exactly will happen depends on the exact car make and model but overall most cars will not care about it at all and will simply turn back on without any problem.

keep in mind though that you will lose power steering and the brake booster while the car is off.

Anonymous 0 Comments

If you put it in neutral first, which you’ll need to do to start it again, you shouldn’t have any issues with the engine or transmission. However, when you turn it off you’ll also lose brake boost and your steering wheel will lock which could be of bigger concern.

Anonymous 0 Comments

I had a loose wire in my ignition circuit. The engine lost all power, and then reconnected again after about five seconds.

It blew the entire exhaust system to pieces. The silencer (muffler) split all the way down the weld and became a flat sheet. The whole exhaust would have filled up with unburnt petrol/air mixture, and then it all got ignited by the next successful fired cylinder.

I don’t see why you would damage a manual transmission (having the wheels drive the engine is no worse that starting the engine by pushing or towing the car).

Unless you disengage the clutch (on a manual transmission), I don’t see why you would lose power steering or brakes. The wheels are still turning the engine, and typically the steering pump is driven by a belt off the engine, and the brake vacuum reservoir is sustained by the pipe from the inlet manifold.

Automatic transmissions may behave differently, although the transmission fluid pump would still be driven off the drive shaft at the engine end.

Anonymous 0 Comments

Definitely depends on the how.
At high speeds is for sure a bad decision. Of course it depends on the car, there can be some differences. Some dont even start when not stopped.
With manual transmission disengaged or automatic in neutral the car while just roll on. But support for breaks and steering will stop. Without disengaging the engine will slow the car down. For starting you need to disengage.
A diesel engine however can be started by dropping the clutch while rolling without ignition turned on.

Anonymous 0 Comments

I had a taxi driver in Spain with a dodgy skoda with a turbo (I can’t exactly remember the details super well I didn’t know much about cars super well). He would rev up the car pretty loud and then completely kill the ignition. Don’t know why he did that but not much happened although it was quite scary. Maybe it was something to do with the turbo?

Anonymous 0 Comments

It’s dangerous, because you’ll “lose” steering control and brake assistance, meaning that the steering wheel will be harder to turn and brake it will hard to push and that with little efficiency.

Putting that aside, when you turn of the engine, nothing out of the ordinary will happen, the engine and transmission are coupled, the engine goes into engine braking and the car will gradually slow down.

Turning on, that’s a different thing and depends on the car, transmission type or how advanced the technology is and what steps the car allows the driver to take when starting the engine,

If by turning on you meant to rotate the key all the way (assuming the car will let you do that), this can mean coupling the electromotor to a flywheel that is already spinning and probably destroying that gear.

If you simply turn the power on, put the gearbox in the correct gear and take your foot lightly off the clutch, normal operation will resume in most cars.

On an automatic transmission, things could differ based on the transmission type and also, depending on how new the car is, on what the car is allowing the driver to do at the starting moment.

Anonymous 0 Comments

Your steering will lock up and you’ll lose control of the car. If you can’t get it started again you’ll either end up in the ditch or oncoming traffic. My friend and I did this 30 years ago as teenagers. It was the ditch for us

Anonymous 0 Comments

You won’t implicitly break or hurt anything. You’ll lose your power steering while the engine is off, and only have 1 or 2 braking attempts before losing the power brakes — but you’ll still be able to steer and brake some, and nothing on the car gets harmed.

You say “at high speed,” so if you’re going fast enough you definitely don’t have to put your car in neutral to restart it — just turn the key back to the “on” or “run” position, and the engine start firing again. Especially in a manual transmission, the engine will still be turning at a normal speed, (since it’s connected to the wheels which are turning); in an automatic transmission, if you’re going fast enough then the same thing will be true, but the connection between the engine and wheels isn’t as direct, so if you’re going too slowly then the engine might not be turning fast enough. (This is basically why you can easily push-start a manual transmission car, but not an automatic transmission one.)

Otherwise, you’ll have turned off all of your other accessories, etc., but that doesn’t hurt them at all.

So, because of the steering/braking thing, you want to be careful about the conditions when you try this, but otherwise, go for it.