Push starting an auto

[rottodiver]

G,day everyone,
After thinking about it I have been wondering if I was to turn my automatic lock up switch on would I be able to push start my troll if I had too??
Scotty

[Alitis007]

No coz the auto uses fluid pressure to engage drive thru the valve body and not mechanical friction like a gearbox!

[taslucas]

No coz the auto uses fluid pressure to engage drive thru the valve body and not mechanical friction like a gearbox!

But a lockup switch locks the drive through the torque converter.

With the TC locked the vehicle will stall without enough revs.

I think there is a possibility although I've heard that if you leave your TC locked and try to start the car you will destroy things.
Interesting though??


FanTapstic!

[Alitis007]

But a lockup switch locks the drive through the torque converter.

With the TC locked the vehicle will stall without enough revs.

I think there is a possibility although I've heard that if you leave your TC locked and try to start the car you will destroy things.
Interesting though??


FanTapstic!

No inside the converter there are fins that the fluid pressure push against to creat the lock up so if the motor is not turning the transmission pump wont creat the pressure to lock the converter to engage drive.

[taslucas]

the "lock up" is created by a solenoid. Wholesale automatics, which manufacture a kit for manual lockup (which is just a bypass switch) say that if you accidently leave the switch locked and try to start the vehicle it will cause major damage. So obviosly theres something in there that is more than fluid presure.

and ill say again; with the TC locked via an aftermarket bypass switch the engine will stall if theres no revs (just like a manual).

Bigrig will hopefully see this soon, he has far more knoweldge than me on the subject

[Alitis007]

The lock up solenoid allows fluid to travel in a more direct path thru the valve body to create lock up that acts like a 5th gear!

If you lock the converter on idle it will over load the motor thus causing it to stall and the damage will be to the converter it self meaning you may sheer off the teeth of its internal drive!!

[taslucas]

The lock up solenoid allows fluid to travel in a more direct path thru the valve body to create lock up that acts like a 5th gear!

If you lock the converter on idle it will over load the motor thus causing it to stall and the damage will be to the converter it self meaning you may sheer off the teeth of its internal drive!!

Cheers mate, thanks for learning me stuff:)

[Alitis007]

Cheers mate, thanks for learning me stuff:)

Dude i almost blew a brain cell trying to remember how it works lmao

No dramas mate !!

[taslucas]

i reckon you should drag tank up and down the driveway and let us know if he starts or binds!!

[rottodiver]

thanks to everyone on there replies...... i have certainly learnt here that if for any stupid reason i was to leave the lock up switch on and stall the car(not that i should ever really make that mistake but stranger things have happened) it is imperitive that the switch gets turned off before restarting the car....
everything aside, autos are really quite a clever invention!!
Scotty

[Alitis007]

The solenoid is like an injector, when power is applied it allows fluid to pass, power off blocks the fluid.

Lock up is the clutches inside the converter meshing together from the fluid that the solenoid that is open.

Scotty's description is right a bout what makes lockup work.

[Bloodyaussie]

Heard of autos being push started many times but not sure with with a 4wd????

Go on George tell me!!!

[taslucas]

yeah ive got a mate that reckons hes done it on an old ford sedan but hes been known to stretch the truth. Maybe next time we're up the rally track and i get an auto going, ill try to "roll" start it

[Bloodyaussie]

I heard you have to get some decent speed up to do it...?

[Alitis007]

I've never heard of an auto being push started ever sorry. I don't know how it would because the converter is what drives the oil pump, an auto works only with oil pressure. I do know that if you tow an auto for more that 2k's you can blow bands and stuff from the wind up.

[NP99]

Just use a porta jump!

[rottodiver]

Just use a porta jump!

I tried using a porta jump on my commodore quite a few months back and it wouldn't start it.. Have you ever tried one?
This was more a curiosity question as I don't really understand how the auto works and after using the lock up switch on the weekend it started me wondering!
Scotty

[NP99]

I tried using a porta jump on my commodore quite a few months back and it wouldn't start it.. Have you ever tried one?
This was more a curiosity question as I don't really understand how the auto works and after using the lock up switch on the weekend it started me wondering!
Scotty

No problems with the porta jump, maybe a dud, dont know!

[Alitis007]

Whats a porta jump??

[NP99]

Portable jump start battery

[rottodiver]

A small battery that plugs into cigarette lighter when you battery is flat and after 5 mins(on memory) it has put enough power into the battery to start the car

Scotty

[taslucas]

Or a jumper pack.
Or jumper leads and a mate.
But that wasn't the question.

Ps, the only time my jumper pack isn't in the patrol is when it's re-charging.
They are great devices:-)

FanTapstic!

[NP99]

Or a jumper pack.
Or jumper leads and a mate.
But that wasn't the question.

Ps, the only time my jumper pack isn't in the patrol is when it's re-charging.
They are great devices:-)

FanTapstic!

Better still, recharge it while driving.....

[Brisat]

towing your jigger too far will bugger the linings on the drive plates in the box and will not start your car
as the oil pump is not working then there is no gears. pull up on a slight downhill, turn the engine and let it roll down the hill and you will see what happens.

[Bloodyaussie]

Conflicting stories when you do a search but it seems the early autos with the Power Glide transmission seem to work as there is a pump before the trans??

Only looked into it quickly but it seems it can work but with only some types??

[taslucas]

Better still, recharge it while driving.....

It takes a long time to recharge them from 12v. If it's dead flat your looking at 10 plus hours to charge off 12v.

FanTapstic!

[taslucas]

Conflicting stories when you do a search but it seems the early autos with the Power Glide transmission seem to work as there is a pump before the trans??

Only looked into it quickly but it seems it can work but with only some types??

That may make sense as to why it's an old rumour. Maybe it could have been done back in the day....

FanTapstic!

[twase]

Auto's work using hydraulic pressure to actuate the friction plates. The pressure is derived from a pump generally mounted on the input shaft directly after the torque converter. Without the motor running you will not have pressure to activate any drive plates. Some early transmissions such as torqueflite had two pumps, one at the front and one at the rear so in theory you could roll start them.

[Bulbous]

I can't see how this is going to work for an auto, hell, it doesn't always work for a manual.
I had a flat battery in my 4.8 (Manual) and even towing it at 40KPH failed to start it.
Seems the fuel pump needs power (probably quite a lot of power considering the amount of fuel it shifts) and if the battery is dead flat then it's just not possible to supply enough to power the pump and start the engine.
In the end I swapped the battery from the running car into mine - started it up and then while it's running swapped the batteries back. Drove straight to the battery shop then.
Next time Nissan tell me my battery is weak I promise to pay attention - they quoted 2/3 of the price I ended up paying.

[douglarv]

The received wisdom around here is that you never try to push start an auto (or tiptronic for that matter) it just doesn't work. We did try push starting a tractor once (I was very young) and destroyed the starter and transmission.