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Discussion Starter #1
anyone know the answer to that ? A friend of mine did that to his car by accident, he was travelling at about 10mph in his 325i automatic.##
 

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booo for body roll.
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uh.. itd prolly damage the engine more. since the drive gear is forcing the engine too operate while the engine is off.. unless when u shut it off the car automatically disengages the tranny from the engine .
 

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ive done that twice before getting outa my car....but it wasnt moving, just stationary and i turned off the ignition...ur friend was movin 10mph and he just turns off the car? i donno about that...
 

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Lying, drunken cheat
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Well, automatics are basically designed to be idiot proof...hence the reason you can't overrev them when downshifting using step mode. I've also noticed it's getting harder to neutral drop them.

Still, I wouldn't do it. I know if you were to turn the engine off with a manual in gear, the car would LURCH HARD to a stop and probably damage something. Did anything like this happen to your friend when he turned the car off?
 

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Discussion Starter #6
akhbhaat said:
Still, I wouldn't do it. I know if you were to turn the engine off with a manual in gear, the car would LURCH HARD to a stop and probably damage something. Did anything like this happen to your friend when he turned the car off?
he was coming to a stop, and the idiot wanted to check if the key would be locked in it's position, (like how when u turn the car off (in neutral) you can't turn the key all the way until the car is put into park) but obviously it wasn't and the engine turned off.. and the car carried on rolling without a jerk at which point he got on the brakes!?

His car seems to run ok, but he's still a bit paranoid. :dunno:
 

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Discussion Starter #7
cheers for all the reply's anyway. I also posted the same question on alt.autos.bmw.

some of the responses have been:

It will do no damage whatsoever. Perhaps what you're thinking of is that most autos shouldn't be towed for long distances or at speed as the oil pump which supplies the bearings etc is engine driven. Your hand book should give details of how far it may be towed without lifting the driven wheels.
Older autos used to have two pumps - one driven off the propshaft, so these could be safely towed or even bump started.


Well first unburnt petrol is sucked into the cylinders and if he turned the ign back on then an explosion might have occurred in the exhaust. Sods Law says it would be in the most expensive part - the catalyst or one of the boxes.
If the ign key had been removed then the steering would have locked and BANG - welcome Mr Tree, Lampost, another car etc.
I have done it on occasions and nothing untoward has happened but then I took that decision.... I cannot advise anyone to do it


in response to the orange post above:

Not even close to correct. All the EFI systems BMWs since the mid-80s won't squirt fuel from the injectors if the ignition is off. Even the L-Jetronic on my '77 530i was ok with this. The K-Jetronic on the smaller engines would squirt until the fuel pressure - which depends upon the ignition switch - ran down. #

and in reply to that

I agree to a point but at some point there will be fuel in the engine and the ign off - no spark. As I said a chance but still inadvisable!

other responses:

At that sort of speed in an auto the engine would simply stop - not be driven along by the car.

Depends on the year of the car. A later model one will lose its transmission program and go into "safe" mode. This is fixed by switching off for a minute or so and then restarting. The car will have to "relearn" your driving style for the trans program. It won't actually damage the transmission unless you thrash it in safe mode.


It is not a good practice, but there is no long term damage that is done by a single instance. Avoid making a practice of this activity, and he will be fine.


thanks to everyone else who replied.
 
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