You rarely need this skill, but when you do need it, then you really need it… how to bump start a car.
I THINK IT WAS 1994, somehere in southern England. A wet, cold miserable early evening and I’d just finished a job with an offsider. We sprinted through the dark across a soaking carpark to my car and leapt in only to find the door ajar and the interior light on. As it had been all day. Slowly leeching the life out of the battery.
We looked at each other. The job had overrun, and text messages from girlfriends had clearly indicated our day wasn’t going to be any better if we weren’t in other locations, quick smart.
I turned the key. The engine clicked. The battery was flat, not a chance it’d be able to start the engine.
But 30 seconds later we were burning rubber out of the carpark.
Here’s how to bump start a car.
What is bump-starting?
Starting a car by using the rotational movement of the wheels to turn the engine over instead of the battery. This only works with manual cars. It is also known as push-starting, roll-starting and clutch popping.
When can you do it?
When you have a flat battery and need to start your manual car regardless. Check your owner’s manual to see if there is any prohibition against bump-starts.
How do you bump-start a car?
Let’s go through a typical scenario. You unlock your car – perhaps noticing it’s a bit slower to react than normal, turn the key and the engine tries to turn over but sighs into silence. Here’s what you do.
- Turn the key to off immediately. You need to conserve what little battery power you have left; and
- Reduce electrical load. Switch off interior lights, music, headlights… everything. Leave it off until you have the engine started.
If you own a manual, you can now bump-start the car. This is how:
- Plan your start. You’ll need to get the car rolling to around 5-10km/h. The easiest method is to find yourself at the top of a hill, but having people push the car also works. You can also use another car to tow yours, but that’s a whole new technique. Before you move though, think carefully about where the car will go. You often might only have enough space or incline for one shot at the start. It is also possible, if you’re fit enough, to push-start a car on the flat, jump in and start in. You also need to remember that once the car is started it should be left running for a while, so plan that too.
- Now you’ve planned it all, switch the ignition to position 2 (just before the key would start the car). This will also unlock the steering wheel so you can turn it.
- Dip the clutch, and select your chosen gear. If you’re going backwards, that’s reverse, if forwards, first gear if there’s very little or space, or second if you can get a bit more speed up (beyond 15km/h).
- Get the car rolling by your planned method. Two very important things to remember – there will be no power steering, and no power brakes. This means that you will need a LOT of force to operate both brakes and steering. Be prepared for this, and don’t be shy about using a lot of force on either.
- As the car reaches about 5-10km/h bring the clutch up. The engine should start. Immediately dip the clutch, and job done. You don’t need to bring the clutch up all the way, just enough for the engine to fire.
- Drive the car. The battery has been depleted, so you need to drive the car for at least twenty minutes to recharge it.
This technique also works with push-button start cars, just push the starter button without your foot on the brake to get to the second ignition point.
Anything else I need to know?
- You probably need to fix a bigger problem. Running a car battery down to the point where it cannot start a car might be an indication of an electrical problem, or an old battery. Even if the battery is new then it will be damaged by such a depletion, so you should consider replacement.
- You can practice it if you like. Find a shallow incline, park at the top, switch the car off, then back to ignition point 2, let it roll down the slope, bring the clutch up in gear and it’ll start. This is not great for the car, but once or twice doesn’t hurt and it’s better to learn the skill before you need it.
- Automatics cannot be bump-started. They must be jump-started which is where you use another battery (sometimes in another car) to provide the electrical power necessary to start the vehicle.
- A small, light car is easier to start than a heavy diesel one – there’s less energy needed to start smaller motors, and petrols are easier to start too.
Two comments: 1) I always was told (and have done this) it’s easier to bump-start in a higher gear for the speed than you would be driving in – so 2nd in a car, or 4th or 5th in a truck. 2) While you cannot push-start an auto, it can be tow-started. Back in the early ’90s we tow started a M-B 300GD when a collapsed cell in a still new battery couldn’t muster the required current. Select neutral, and at about 80km/h, pop it into 4. Engine fired up straight away, with no adverse effects.
Rob W
Christ this bring back a few memory’s , back in my younger days when l work at British rail work shop in Asford Kent (UK) on the night shift welding rolling stock (1972-81) , in the morning many a car kneaded a jump start,,, in the mornings it was quite a morning exercise for most of us, and a lot of piss taking about English cars ,most of the jap cars started, first turn, l had a corolla 1200 SR two door coup RED.
l didn’t know you can jump start a car BACKWARDS !!!!! AUTO,S battery only, over here in Aussie, 95% are auto “”LOL”” jump leads are part of everyone’s kit !!!! and be-leave it or not its the heat over here that kills most battery’s life “”lucky if they last 4 years “(not cover by warranty eather ))
The crucial bit is wrong here. In order to turn the engine over most easily, you need to maximise the torque exerted by the momentum of the car, via the transmission, on the engine. It’s the opposite of maximising the torque of the engine on the forward motion of the car. That means jump-start in a high gear (closest to 1:1). Not only does the engine turn over and start more easily, the stress on the transmission is much less. It is painful to any mechanically sensitive person to hear the chirp of rubber and the wrenching of the transmission as the car lurches to a halt when some turkey tries to jump-start a car in low gear. If you’re the one pushing, and the driver insists on trying to drop the clutch in low gear, just walk off and leave him to it. Better than smashing your face into his back window.
I must agree with Richard – when push starting, try top gear first – the engine only has to hit a few hundred revs (not even idle speed) to start, as long as there is sufficient power from the battery for a spark. The trick is to push the clutch pedal back in immediately the engine fires.
Older automatic transmissions with a rear oil pump could be push or tow started – if no rear oil pump, no oil pressure and hence no drive between the wheels and the engine.
However, with modern cars fitted with catalytic converters, the warning is not to attempt to push start as unburnt fuel will go into the converter and may result in an explosion.
tried this (1st gear) and it worked 1st time. And i’m a hopeless WOMAN lmao. saved me having to roll it down the road and wait til the morning for someone to help me rescue it.