How to bump start a car
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.