Starting an automatic with a dead battery
Thread Starter
|
Junior User
Joined: Mar 2005
Posts: 53
Likes: 0
From: Washington
Starting an automatic with a dead battery
A few years ago I was taking a vehicle in for its license inspection. A young fella in a pretty yellow truck was in front of me... Don't remember the make and model but he was fixing it up.
As he was leaving the motor killed and his battery was shot. I told him I'd give him a jump when they were done with me.
He said if I'd push him that'd be just fine. I said - but you've got an automatic? He said yup but it was tight enough that he could compression start it.
So, if I remember right, we both pushed it backwards a few feet. Then he jumped in the cab and I pushed him forward - like six inches and vroom he took off waving.
Now I might have some of this a little turned around since it was a few years ago. But I've since wondered how that truck started.
Can someone explain it to me?
Mike
As he was leaving the motor killed and his battery was shot. I told him I'd give him a jump when they were done with me.
He said if I'd push him that'd be just fine. I said - but you've got an automatic? He said yup but it was tight enough that he could compression start it.
So, if I remember right, we both pushed it backwards a few feet. Then he jumped in the cab and I pushed him forward - like six inches and vroom he took off waving.
Now I might have some of this a little turned around since it was a few years ago. But I've since wondered how that truck started.
Can someone explain it to me?
Mike
Postmaster
Joined: Jul 2003
Posts: 2,628
Likes: 0
From: Calgary, Canada
I wouldn't think it possible with a torque convertor between the crankshaft and transmission. If you put your auto vehicle in gear, on a hill and let off the brake does the engine turn as the car rolls down the hill?
FTE Leadership Emeritus
Joined: May 2004
Posts: 18,787
Likes: 30
From: Melbourne, Aus
hmmm...
This has me bemused, I have never tried it, purely because I never thought it would work.
I spose though in theory if you got enough road speed up, and then put it in the 1st selector it should work, shouldn't it?
This has me bemused, I have never tried it, purely because I never thought it would work.
I spose though in theory if you got enough road speed up, and then put it in the 1st selector it should work, shouldn't it?
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
The only automatic tranny I know of that could be roll started was the old 2 spd powerglides in the late 50's early 60's chevies. This is because it had two oil pumps. One was up front driven from the torque convertor like every automatic has, and it had another on the tailshaft, which could be turned if the car was towed. It would build enough pressure up in the system to activate the tranny circuits if you pulled it up around 20mph.
Do not have a clue what happened in your situation. If you do not have any pump pressure, how can you lock the planetaries so power is transferred through? Even if power was transferred through, you would still have to get some rpms up, to compensate for torque convertor slippage.
Do not have a clue what happened in your situation. If you do not have any pump pressure, how can you lock the planetaries so power is transferred through? Even if power was transferred through, you would still have to get some rpms up, to compensate for torque convertor slippage.
Posting Guru
Joined: Jul 2003
Posts: 2,210
Likes: 2
Originally Posted by furball69
I wouldn't think it possible with a torque convertor between the crankshaft and transmission. If you put your auto vehicle in gear, on a hill and let off the brake does the engine turn as the car rolls down the hill?
The torque converter isn't the problem. As long as it is full of oil it will transfer torque in either direction.
The problem is that without the engine running (on most automatics) there is no pressure to engage the clutches and/or bands that are needed to spin the engine. Some transmissions, and they are rare, have a pump on the output shaft that will create pressure to engage the clutches/bands without the engine running. If the trans has an output pump you can push start it.
Last edited by Casey; Jun 5, 2005 at 08:27 PM.
Senior User
Joined: May 2003
Posts: 455
Likes: 0
From: Alaska
If the car was made in the fifties or earlier, it may have a rear pump in the transmission and may be capable of push starting, none of the automatics since then have a rear pump and cannot be push started.
That said, there may be one that I'm not aware of.
That said, there may be one that I'm not aware of.
More Turbo
Joined: Aug 2004
Posts: 577
Likes: 15
From: Georgia
Franklin2 is correct about the older powerglides. My dad, one of his friends and myself went fishing at Lake Seminole, Ga back when I was in high school. He had a 1956 Oldsmobile which he used to pull our 17' boat. We had just launched the boat at dusk to drive it to our lake side campsite and he tried to start the car to pull the boat trailer out. Starter went south. He got one of the park rangers to pull him out of the water with a tractor. The ranger pulled him around the park until they got up enough speed and the Olds engine roared to life. We drove it into town and was very lucky to find a mechanic willing to work after hours to install a rebuilt starter. Our fishing trip was not delayed.
Trending Topics
Fleet Mechanic
Joined: Sep 2002
Posts: 1,769
Likes: 7
From: Gretna ,LA.
I have started a Ford vehicle by pushing it about 45 mph, I cant remeber, I believe it was my 63 galaxie.But I remember growing up it was widely known you could start automatics by going 45 or faster.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Rezvani's Latest Post-Apocalytic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
Thread Starter
|
Junior User
Joined: Mar 2005
Posts: 53
Likes: 0
From: Washington
I wish I would've paid more attention but I had no idea the truck would actually start.
If I were going to make my best guess: The truck body was GM - looked early 70's - but he'd just painted it and had no trim or moldings on it to speak of. I have no idea what he had for a drive train - It was definitely a project for the kid. He'd just got it to the point where he could drive it and needed to get it licensed. The interior was still tore apart.
Here's another part I might have confused... I can't remember whether we pushed it forward first and then it started when I pushed it backwards or vice versa.
I also don't know whether it was in drive, low, reverse or what.
I do know I wasn't pushing him at 45+. So far still a mystery.
If I were going to make my best guess: The truck body was GM - looked early 70's - but he'd just painted it and had no trim or moldings on it to speak of. I have no idea what he had for a drive train - It was definitely a project for the kid. He'd just got it to the point where he could drive it and needed to get it licensed. The interior was still tore apart.
Here's another part I might have confused... I can't remember whether we pushed it forward first and then it started when I pushed it backwards or vice versa.
I also don't know whether it was in drive, low, reverse or what.
I do know I wasn't pushing him at 45+. So far still a mystery.
Postmaster
Joined: Oct 2004
Posts: 4,155
Likes: 0
From: Southern Louisiana
My cousin pushed started an 85 f150 auto. He was being towed with no battery in the truck and he slammed the shift from neutral to first and the dang thing started. I was sitting right next to him and didnt think it was possible. I have since tried reproducing it and could never do it.
Senior User
Joined: Jun 2003
Posts: 150
Likes: 0
From: Milpitas, C.A.
My friend had an AMC pacer that loved to eat up batteries. It would sit in the garage most of the time until we felt the need to relive the adventures of Bill and Ted 
. To get it started we would put the car in drive and just push it down his driveway. Granted he had long driveway that was slanted downward. By the time we reached the end of his driveway we would have mangated to get the thing started and we would just drive off.
. To get it started we would put the car in drive and just push it down his driveway. Granted he had long driveway that was slanted downward. By the time we reached the end of his driveway we would have mangated to get the thing started and we would just drive off.
Laughing Gas
Joined: Apr 2002
Posts: 845
Likes: 2
From: Bakersfield Ca.
Interesting thread.
If I remember correctly, I had read sometime back in an automotive Q&A column this very question. The answer was the same as some here, that one had to get the vehicle going about 40mph in order for it to work.
Here's another angle. If one has two gas tanks and one of them runs out of gas on the highway, the engine is dead. Switch tanks and the engine comes back to life. So, if the engine is dead then it's not driving the transmission but the transmission is driving the engine. Would this follow the same theory as coast starting an automatic? I've switched tanks on my truck going as slow as 30mph and had enough speed for the engine to fire back up after the fuel as reached the carb. Thoughts?
If I remember correctly, I had read sometime back in an automotive Q&A column this very question. The answer was the same as some here, that one had to get the vehicle going about 40mph in order for it to work.
Here's another angle. If one has two gas tanks and one of them runs out of gas on the highway, the engine is dead. Switch tanks and the engine comes back to life. So, if the engine is dead then it's not driving the transmission but the transmission is driving the engine. Would this follow the same theory as coast starting an automatic? I've switched tanks on my truck going as slow as 30mph and had enough speed for the engine to fire back up after the fuel as reached the carb. Thoughts?
Last edited by DailyDriver; Jun 7, 2005 at 02:05 AM.