Push starting modern cars?

start
batteries

#1

I ask for future reference: can modern cars (modern as in fuel injection, high-pressure fuel pumps, etc.) with manual transmission be push-started? I have a 2001 Honda Civic HX (manual trans), and the owner’s manual says nothing about push-starting, whereas the owner’s manual of my 1994 Ford Ranger (manual trans, FFI) specifically forbids push-starting due to specific mechanical damage that will occur.



If I can push-start my Civic without damaging it, what is the procedure?



Please understand I would consider the push-start option only if the jump-start option is not available (and I do carry jumper cables in my trunk). This question is for future reference, and I hope never to need to do it. Thank you.



p.s. I know a guy who, in his youth, always parked on a hill because his battery was always getting stolen.


#2

In theory you can push start, or roll start, any car with manual transmission, fuel injection notwithstanding. I don’t know why your Ranger’s owner’s manual specifically forbids this technique. Strange. As for your Civic, if the owner’s manual has nothing to say about a roll start, you may assume you are permitted to do so.

I occasionally do this just for kicks when parked facing uphill. It goes like this: key on, shift into reverse with the clutch pedal depressed, and release the parking brake. Let it roll back. It doesn’t take much speed – maybe 5 mph. Just release the clutch and the engine fires right up.

On level ground, use first gear and have your wife push forward to the same 5 mph before releasing the clutch. You two should practice a few times to gain confidence.


#3

i agree except use 2nd or 3rd gear so theres less of a jolt when you bring the clutch up,here in england about 80 % of cars are manual and i push started a collegues van recently with no problem.


#4

You can’t always do it with electronic fuel injection. It very much depends on how dead the battery is or what’s wrong. For instance I had an F250 diesel with a Powerstroke 7.3L. These engines have electronic fuel injectors and I once tried to do it when my starter cable burnt in two. The problem was that cable also supplied the power for the fuel injectors and she would turn over but not start because there was no fuel. Another time I had an alternator go south on me comeing back from the farm. It was a 25 mile drive to the house and it was dark. About 5 miles from the house on the interstate the battery got dead enough that it couldn’t power the injectors and died at 70 mph. I had enough speed to make the interchange, but had to call a tow truck to get it to the house.

Skip


#5

Aha.

According to the Hanyes manual for this vehicle, “When the engine is running, there is always voltage on the ‘hot’ side of each fuel injector terminal. The PCM turns the injectors on and off by switching their ground paths on and off.”

Does this mean it may be push-started with a (mostly) dead battery, but not with a completely dead battery (or no battery at all)?

I would assume the answer to lie within the realm of the professional mechanic. To bad there aren’t any of those around who answer such questions for free, like say, on a light-hearted radio call-in show. That would be cool. Someone should do that.

Would any of the rest of us have the technical awareness to answer with such insight?


#6

You need enough power in the battery to energize the field of the alternator. With no battery or a fully “dead” one you cannot push start a manual transmission vehicle as the alternator will not produce voltage to power the ecu.

Back in the 50’s and early 60’s cars were equipped with “generators” vs alternators. These you could push start as the generator always had enough magnetisim left in them for the field.

I have a 59 T-bird with auto, you can push start this car as the tranny has a rear pump which were removed around the mid 60’s as they were redundant as once the engine was running the front pump did most of the work,plus the bird has a generator. All you have to do is get the car up to 20-25 mph turn ignition on and drop it into “L” and it will start.

You can also use “D2” if the roads were wet or slippery preventing real wheel lockup especially on snow or ice.

With a generator you can push start with a “dead” battery. The draw back of a generator is, they produce lower amperage and will have a hard time keeping up with the load escpecially at night with headlights and heater going when the engine is at idle.


#7

“Does this mean it may be push-started with a (mostly) dead battery, but not with a completely dead battery (or no battery at all)?”

Recall that even before the days of computer-controlled fuel injection, the ignition still needed electrical power to fire the spark plugs. The push start provided that power, essentially by turning the alternator/generator. The plugs could then fire up, almost immediately. The same principle applies to modern cars. Hopefully the car has maintained its fuel pressure or else gnition may take a second or two longer, waiting for the electric fuel pump to catch up.

It is seldom that a battery is ever completely dead. One that seems so is typically able to cough up a few volts, just enough to get things started.

You raise a good point about whether a car can be started with no battery at all. I believe the answer is yes, although I have no valid information on this point. At issue is 59tbird’s note that a generator has enough residual magnetism to cough up 12 volts even with no attached battery. I believe an alernator can do the same thing, even drawing a bit of magnetism from the Earth’s magnetic field. The way the initial induced voltage is fed back to the coils suggests that the barest trace of residual magnetism is enough fire up the alternator to sufficient levels. Again, this notion is largely speculative.


#8

Some cars/trucks computers incorporate the starter engagement into the computers start function and if pushed the vehicle likely won’t start. Off the top of my head I don’t recall which makes, though.


#9

RE: Car with no battery that uses an alternator

I never knew of any alternator that would be able to “self excite” itself. It needs something to get the field current going.
But you never want to run without the battery in any case. You’ll likely blow some of the car’s electronics.

Car alternators don’t just produce a pure DC voltage. They also emit lots of voltage spikes. Those spikes can be quite harmful to a vehicle’s sensitive electronics.

When a battery is connected, even if it’s dead, it acts like a huge capacitor - absorbing all those voltage spikes. The result is a smoothed-out DC voltage.

Back in the 60’s when batteries would get stolen from cars parked at the local commuter train station parking lot, I’d jump start the customers and have them drive back to the garage without any battery. I’m surprised it didn’t blow any transistor radios or lamps. I would never do that today.


#10

Sellf exciter ‘one wire’ alternators do exist for special applications, you’ll find them on most construction plant like Caterpillar. I think they are also used on some race car applications.

Self exciters are rev triggered using the field residual magnetism, they don’t need an exciter light. I doubt that any regular street car is fitted with one of these.


#11

Roll start a car or truck with reverse? You could, but risk damaging the reverse gear. I’d restrict that to dire emergency only.


#12

Thanks everyone.

Before I posted this question, I searched a variety of sources for “push start” and came up empty. It didn’t occur to me to search for “roll start.” I’ve never heard it called that before, but apparently Tom and Ray recently addressed this basic question in a column: http://www.cartalk.com/content/columns/Archive/2007/February/02.html.

As far as the procedure goes, 1) don’t do it w/out a battery connected to at least suppress alternator voltage spikes, 2) get it rolling in neutral to ~ 5+ mph, 3) pop the clutch in 2nd gear – is that right?

Of course, personally, I would only “roll start” a car if I had a dead battery and no jumpstart options.


#13

It depends on how fast you are rolling. If you got a hill that will get your car rolling up to 20 mph, gently let the clutch out in fifth gear to start the engine. The higher the transmission gear, the easier it is to turn the engine.


#14

Thanks Scudder. I never knew that.


#15

I’ve done it before on my 03 Mustang for sh*ts & giggles. Worked flawlessly.


#16

I’ve always assumed that the reason why a lot of owner’s manuals forbid is because there’s always a chance you can run someone over or crash into a wall or some other imagined mayhem that they don’t want to get sued for.

The “catalytic convertor warnings” sticker on the sunvisor of my '76 Chevy Pickup says not to push start the truck because it will damage the catalytic convertor. I have no idea how this would be, and for what it’s worth, I roll start the thing all the time and the convertor still appears to be working.


#17

In the old days one could push start a vehicle with a near dead battery because the ignition coil could be triggered with very little juice.
With modern cars and the high current draw by the fuel pump, ECM, and a few dozen other things little if any of it will work when the voltage drops below a certain point. Many cars may not start at all when the voltage hits 10 volts or so amd it’s easy to hit that benchmark with a run down or bad battery.

With a good, fully charged battery on a manual transmission I don’t see why it can’t be push started. The real trick is finding something to push with or on since thin plastic so maybe bump starting is a better term. :slight_smile:


#18

On level ground, I used to “scooter start” my old VW. With the door open, I’d use my left leg to push the car along and have my right foot on the clutch. The trick was climbing back into the car and stopping it before it crashed into something.

Maybe that’s the solution for no pushing points on modern cars.


#19

Your owner’s manual is always the definitive authority. The owner’s manual for your Ford says “don’t do this”, so don’t do it, no matter what we say.

The Civic, it depends. Your fuel system needs to be pressurized for your injectors to work properly, so if the car’s been sitting for awhile and the battery is dead you may have a problem doing this. The alternator needs to put out enough to run the pump and pressurize the system as well as fire the spark plugs, all while compensating for the fact that it’s output is all being soaked up by the dead battery trying the recharge itself.


#20

The “catalytic convertor warnings” sticker on the sunvisor of my '76 Chevy Pickup says not to push start the truck because it will damage the catalytic convertor. I have no idea how this would be, and for what it’s worth, I roll start the thing all the time and the convertor still appears to be working.

I believe the issue is unburned fuel collecting in the catalytic converter that then goes kaboom! when the engine finally starts. This is usually considered to be a bad thing for the cat.