Have you ever been stranded by a dead battery? If you have a manual transmission, a rolling start can help you escape being stuck by the side of the road. This technique, also known as “bump starting” or “push starting,” relies on your engine’s compression to bypass the electrical starter and ignite the fuel in the pistons. If you’ve got enough room — and hopefully, a downhill slope — it’s a alternative way to start your manual-equipped automobile in an emergency situation. Here are six tips for a successful rolling start:
1. Find a Hill
In principle the instructions on how to push start a manual car are simple: turn the ignition key, put the clutch in, get the car in gear and then start to move forward. Once you’ve gathered enough speed, “pop” the clutch and the engine should fire.
In reality, it’s not always that easy to move something as heavy as a car for a bump start, especially if you don’t have any friends to help you push. It could be tempting to ask a passing motorist to push your car with theirs, bumper to bumper, but don’t — it’s simply too dangerous, and it could damage your car or lead to injury. Also resist the temptation of starting a manual car by pulling it with a rope or chain for the same reasons.
The best solution for how to start a manual car is to point your vehicle down a hill that’s steep enough to get you rolling at 5 to 10 miles per hour, but not so intense that, if your car doesn’t start right away, you can’t easily stop. Keep in mind it may be harder to steer (no power steering without a running engine) and to stop (no power brakes without engine vacuum), so plan your roll-start location carefully. Also keep in mind that if your first attempt fails, you may need to find the next hill or somehow get your vehicle back up the hill to try again.
2. Choose a Gear
You must select a transmission gear that will offer enough torque to spin the motor, but not so much that it acts as a brake and stalls your forward momentum. If you have ever downshifted to slow down then you know how much effort can be created from engine compression. Typically, second gear is a good option for most vehicles. But never, ever do a rolling start in reverse — it’s too risky to try to watch where you are going, steer and pop the clutch all at the same time.
3. Prepare To Start
Turn the ignition key to the “ON” position. This both unlocks the steering wheel and allows the engine to crank once things are moving sufficiently. Keep your foot firmly on the brake or set the parking brake.
4. Pop The Clutch
Push in the clutch, release the brakes and let your vehicle start rolling down the hill on its own or from a helpful bystander. After you’ve gathered speed, you need to release the clutch quickly (pop the clutch) and let the transmission send the motion of the vehicle’s differential to the engine, spinning it up and causing it to fire. You need to release the clutch quickly but smoothly to help conserve momentum.
Only vehicles with a human-operated clutch can successfully pull off a rolling start. A traditional automatic doesn’t feature the same capability thanks to the fluid coupling design of the torque converter and the pressurized fluids requirements to move the gears. And while modern “dual clutch” designs may use a pair of clutches, they are operated by computer and are not designed to channel power back into the engine. So if you are wondering how to bump start a car with an automatic transmission, the answer is you don’t. If that third pedal isn’t there (paddle shifters don’t count), trying to do a roll start will only result in damage to your transmission.
6. Your Mileage May Vary
Not every vehicle can be cranked with a rolling start. Before attempting a bump start it is a good idea to check the owner’s manual to see if the practice is not recommended. If the vehicle manufacturer says no bump starting, trust them. Also some vehicle systems may not be able to function if the battery is truly dead. Things like ignition coils, computers, and electric fuel pumps still need some power to get the engine started. Lastly some vehicles are just difficult to start without battery power. A diesel engine benefits greatly from glow plugs pre-heating the combustion chambers, but without that help it could make a cold rolling start almost impossible.
When thinking about how to start car with a dead battery the safest and best solution is to keep a battery jump box in the vehicle for just such an emergency. NAPA stocks a wide variety of portable jump starters so you can find the one that best matches your needs.
Check out all of the vehicle batteries available on NAPAOnline or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on how to start a manual car with a dead battery and how to pop a clutch, chat with a knowledgeable expert at your local NAPA Auto Parts store.
Photo courtesy of Wikimedia Commons.
Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time. I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.