Push starting an automatic car

[OilUzer]

I always avoided auto trans cars but was finally forced to drive one regularly a few years ago ... by choice lol. The v8 I liked only came with auto. Not bad since it forced me to learn a little and paying attention to how auto trans works. I still prefer 5 speed manual. if not, 5 speed auto. Mine is 6 speed. The 6th gear is basically useless unless you are on the flats and doing 70 with no load! Not sure why some new cars come with 10 speed auto! Hope I don't have to ever buy one of those.

Just curious, can you push start an auto? Push it or let it roll (e.g. a slight downhill) in N and once rolling, shift into D?
Would the torque converter engage and start the car?

 

[Hall]

No

 

[mk378]

Automatic cars can't be push started because the gears will not engage without fluid pressure from the main pump. The pump is driven by the engine. Turning the wheels with the gears not engaged will not turn the pump.

 

[Dave Sherman]

Nope. Usually the engine has to run to provide hydraulic pressure to engage the clutches, otherwise it's always in neutral. I've heard a few have an additional hydraulic pump driven by the driveshaft, but most don't. The driveshaft driven pump is mainly to keep it lubricated if you have to tow it, and since most transmissions these days are electronic, I'm not sure the ECU would activate the solenoids to engage the transmission if it knows the engine isn't running.

 

[dishdude]

There are some older autos that can be push started as the wheels moving will also turn the pump and they have no electronics. I don't know which ones though! Before my time.

 

[atikovi]

Originally Posted by OilUzer
Just curious, can you push start an auto? Push it or let it roll (e.g. a slight downhill) in N and once rolling, shift into D?


Not any automatic made in the last 50 years or more. I recall thumbing through some owners manuals from cars of the 50's and they did show how to push start an automatic. Not sure how late a model it would be possible on. I did have a Smart you could do it on but it has an automated manual transmission so doesn't really count.

 

[supton]

Old GM Powerglides (pre 1967?) could be push started. I'm sure a few others (MB?) too.

Just because it has 10 speeds does it mean it "has to be" overgeared. The rear end ratio comes into play too. But generally speaking, yeah top gear is going to be crazy high. Think of it this way: if top gear was low enough that you could climb most hills without downshifting, then it's not tall enough for the flats--the engine could be turning slower on flat ground, potentially saving gas.

 

[Donald]

No push starting or parking the vehicle on top of a hill and rolling it down the next day to start.

And you need to read the manual to tow. Best towed in a flatbed these days,

 

[Dave Sherman]

Come to think of it, can you even push start a modern manual? I've always wondered if the ECU would even turn on the fuel pump, fire the ignition, and fire the injectors if the engine just started turning. I know the computer usually turns off the fuel pump if it senses the engine isn't running.

 

[atikovi]

Owners manual says not to push start because unburned fuel could damage catalytic converter.

 

[zorobabel]

Originally Posted by Dave Sherman
Come to think of it, can you even push start a modern manual? I've always wondered if the ECU would even turn on the fuel pump, fire the ignition, and fire the injectors if the engine just started turning. I know the computer usually turns off the fuel pump if it senses the engine isn't running.

The newest car I push started was a 99 Camry with the 5SFE. I haven't tried anything newer.

 

[Skippy722]

Originally Posted by OilUzer
The 6th gear is basically useless unless you are on the flats and doing 70 with no load! Not sure why some new cars come with 10 speed auto! Hope I don't have to ever buy one of those.


Those 8 and 10 speeds are all under drive except the last 2-3 gears. Allows them to get away using crazy tall axle ratios without killing acceleration... my 300 has a 2.62:1 axle, cruises 60mph at less than 1500rpm, but is capable of 0-60 in 6.6 seconds, and shifts faster than any human is capable of.

But no, you cannot push start an automatic.

 

[IndyIan]

Originally Posted by Dave Sherman
Come to think of it, can you even push start a modern manual? I've always wondered if the ECU would even turn on the fuel pump, fire the ignition, and fire the injectors if the engine just started turning. I know the computer usually turns off the fuel pump if it senses the engine isn't running.

I've successfully push started manuals with live batteries. I even drove my 03 tracker around for a couple days with no starter, just parking on hills while we waited for a starter to come in for it. I could see potentially push starting a manual car with a dead battery if you had a big enough hill to get the electrical system seeing some voltage for long enough to get the fuel pump going.

 

[Rmay635703]

Yes modern manuals will push or bump start

Compression is high so expect to need a bit of speed to pull it off

 

[Linctex]

Originally Posted by Rmay635703

Compression is high so expect to need a bit of speed to pull it off


Always use 4th or 3rd, never 2nd gear.

 

[atikovi]

And if the battery is dead, like under 9 volts, it's not going to start no matter how fast you push.

 

[tomcat27]

I believe that some Saturns have the pump driven by the output shaft.

 

[Propflux01]

My brother tow-started his 1972 Challenger while I was towing him with a rope. We were going about 35 mph, he stated he just stuck it in drive and it started.

 

[Hall]

Originally Posted by Linctex
Originally Posted by Rmay635703

Compression is high so expect to need a bit of speed to pull it off


Always use 4th or 3rd, never 2nd gear.

Last car I probably push-started was an '88 Honda Prelude Si and I used 2nd gear. It felt perfectly fine with no jolting or jarring that I recall. It doesn't take much speed at all either as I've done it by myself - pushing the car, jumping in the driver's seat, and popping it in gear to get it running. At those speeds, I think it would stall quicker than one could push the clutch pedal back in if using 4th gear. 3rd gear seems possible though but you'd still have to put the clutch in, I think.

 

[eljefino]

The 40-year-old-design auto trans in 1980s benz diesels would do it in theory. One needed enough speed. I should have tried, when I had mine.

I imagine it could be tricky roll-starting something with Passlock or other transponder anti-theft thingies. One work around might be turning the non-functioning key while popping the clutch.

My 02 camry stick shift roll started. It was a base model with brass keys.