Car in automatic transmission with gear in neutral position

[skp288]

Can I let a car roll down a hill with the gear in neutral position when it has an automatic transmission?

[qapmoc]

Yes

[Toureman]

Yes.

It is not safe to two a car with an auto gearbox as with the engine not running the oil is not pumped round the gearbox so damage could occur. It is usually reccomended that if a tow is needed do not go over 20mph and only for a maximum of 20 miles

[skp288]

Thank you.

I was told that for a car with auto gear, the gear should always be in the 'drive' position whenever it is moving; that the gear should not at any time be in the 'neutral' position.

I was told further that the gear should not be in 'neutral' position, even when the car is stopped at a traffic light.

Your answers, which are appreciated, suggest that the above is no true?

[qapmoc]

As Toureman says most auto g-boxes have a limit on how far the vehicle can be moved without the engine running and with the box in ''N'' , this is because the auto g-box has an oil pump for the hydraulics/lubrication system which is driven from the engine and if the engine is not running then only the residual oil will lubricate the system and this will allow it to be moved safely for only a few miles at slow speed before excess wear starts to take place.
As for the second question, while it is normal to leave the auto g-box in ''D'' when waiting at traffic lights etc it is certainly not a requirement and there is no reason you could not put it in ''N'' if you want to. I don't see why you would want to unless your handbrake is not good enough to hold the car on a slope with the gearbox trying to creep forward.

[oldhamfan]

That begs a further question - why is there a neutral if it should always be in D (or obviously R) when moving, and P when stationary?!

[qapmoc]

"N" Neutral is just that, no gear is selected and the drive is free to move, for example to roll down a hill.
''P'' Park actually locks the drive mecanically and the drive wheels cannot be rotated so the vehicle cannot move of its own accord. (NEVER EVER engage ''P'' when the vehicle is still moving)

[markja]

oldhamfan, how would you rev the engine when doing repairs/tests to said engine if there was no 'N' ?

[skp288]

Thank you for the discussion.

I drove a manual transmission gear car before my present car, which has auto gear. When petrol prices were high some years ago, I tried to save petrol by letting the old car roll down hill or glide towards a traffic light, by disengaging the gear - in other words, with the gear in the neutral position.

With the present car, which has an auto gear, I did the same, and ended up having to have the gear repaired, twice in the past two years. I was told that that was because of my driving the auto gear car, with the gear in the neutral position. The mechanic told me that that had damaged the gear. Hence the need to repair it twice, expensively, during the past two years.

So the mechanic was wrong?

[markja]

skp228, the car cannot tell the difference between freewheeling down the hill and being towed. mr car maker tells you not to tow your car for more than X miles or faster than X mph for a reason.it boloxes the gear box!
if you wish to find out why, take an engineering course so you understand general mechanical principles and all will become clear. alternatively, trust mr car maker to have done said course and know what he's on about.

[markja]

also, if you car has electronic fuel injection, when going downhill (or rolling along )with the throtle released the car will use NO fuel at all. if it's in neutral the car will use the fuel required to make it tick over.
stick it high gear and take your foot off the throtle on downhills (and mainroads, throtle off early to aviod braking.) only do this safely though!