Coasting in neutral harmful?
01-14-2011 | 11:27 AM
#31
Seasoned Member
Joined: Nov 2010
Posts: 473
Likes: 2
From: Cincinnati, Ohio
Year: 2004
Model: Grand Cherokee
Engine: 4.0 I6
I know it is recommended for some vehicles with automatic transmission not to coast downhill in neutral. With the price of gas going up again, I am tempted to play the coasting game downhills to save on fuel in 2 wd only.
Anybody know if this can be harmful to the transmission?
I own a '97 4.0 w/ auto. Thanks, Henry
Anybody know if this can be harmful to the transmission?
I own a '97 4.0 w/ auto. Thanks, Henry
01-14-2011 | 11:28 AM
#32
Seasoned Member
Joined: Sep 2009
Posts: 273
Likes: 1
From: Coventry, CT
Year: 2000
Model: Cherokee
Engine: 4.0 high output, Alabama Cylinder head, 60mm bored TB
If you have an automatic, shifting to neutral will save you absolutely no fuel. You may even get better mpg coasting in drive. Theres been many tests done on this just search google. A manual it may gain you some mpg since they don't coast in gear like autos do in drive.
Its a jeep though, the little money you save putting it in neutral (if any) will be needed when your NSS wears out.
Its a jeep though, the little money you save putting it in neutral (if any) will be needed when your NSS wears out.
01-14-2011 | 11:29 AM
#33
Seasoned Member
Joined: Nov 2010
Posts: 473
Likes: 2
From: Cincinnati, Ohio
Year: 2004
Model: Grand Cherokee
Engine: 4.0 I6
You're actually HURTING your gas mileage by shifting into neutral.
Here is why:
When you coast in gear, the injectors are shut off.
When you coast in neutral, the injectors have to supply enough fuel to maintain an idle.
Not to mention the damage you can (and will) cause to your transmission syncros switching back and forth while at speed. You also lose the ability to engine brake. There is also the frightening possibility that you might put the transmission in reverse, which would not end well.
As for the transmission fluid pump working in neutral - it does, but only to the torque converter.
Here is why:
When you coast in gear, the injectors are shut off.
When you coast in neutral, the injectors have to supply enough fuel to maintain an idle.
Not to mention the damage you can (and will) cause to your transmission syncros switching back and forth while at speed. You also lose the ability to engine brake. There is also the frightening possibility that you might put the transmission in reverse, which would not end well.
As for the transmission fluid pump working in neutral - it does, but only to the torque converter.
01-14-2011 | 06:22 PM
#34
CF Veteran
Joined: Nov 2008
Posts: 7,874
Likes: 98
From: Northern Ontario, Canada
Year: 1990, 1999, 2000
Model: Cherokee
Engine: 4.0
your torque converter seal won't last long when coasting in neutral with the engine shut off. it needs to be running to get lubed.
happened to me when i was trying to get my xj home from wheeling while it was overheating. i thought i would just throw it in neutral and shut it off when it got hot. the temp would drop dramatically upon restart, but only took a few times until it started leaking tranny fluid onto the exhaust, thus covering everyone behind me with a cloudy oily film.
got home and swapped out tranny's and put in a new rad.
happened to me when i was trying to get my xj home from wheeling while it was overheating. i thought i would just throw it in neutral and shut it off when it got hot. the temp would drop dramatically upon restart, but only took a few times until it started leaking tranny fluid onto the exhaust, thus covering everyone behind me with a cloudy oily film.
got home and swapped out tranny's and put in a new rad.
01-14-2011 | 08:18 PM
#35
Senior Member
Joined: Sep 2010
Posts: 905
Likes: 1
From: Llewellyn, PA
Year: 1998
Model: Cherokee
Engine: 4.0L I6
When you're going down a hill backwards with no power and traffic is flying up the hill behind you, yes it's scary. When you just lose power on a regular 1 or 2 lane road and you have somewhere to pull off, then no it's not scary
Going back on topic, I don't think this would hurt your vehicle unless you are shifting form neutral into drive while moving, then I think it might do some damage to your transmission. As for gas consumption, if your RPMs are lower when you are coasting (which they should be) it should then use less gas.
Going back on topic, I don't think this would hurt your vehicle unless you are shifting form neutral into drive while moving, then I think it might do some damage to your transmission. As for gas consumption, if your RPMs are lower when you are coasting (which they should be) it should then use less gas.
Last edited by Griff94; 01-14-2011 at 08:23 PM.
01-14-2011 | 10:39 PM
#36
Newbie
Joined: Jan 2010
Posts: 22
Likes: 0
From: Pittsburgh,Pa
Year: 2000
Model: Cherokee
Engine: 4.0L
I kick mine into neutral while rolling to a stop all the time. Not to save gas but to go a little easier on the brakes. Years of driving a manual I guess. I have never had a problem with my AW4.
01-15-2011 | 09:07 PM
#37
Member
Joined: Nov 2010
Posts: 194
Likes: 0
Year: 1994
Model: Cherokee
Engine: 4.0
Originally Posted by Urbncby
I kick mine into neutral while rolling to a stop all the time. Not to save gas but to go a little easier on the brakes. Years of driving a manual I guess. I have never had a problem with my AW4.
01-16-2011 | 01:14 AM
#39
CF Veteran
Joined: Sep 2010
Posts: 1,992
Likes: 0
From: West Bloomfield,MI
Year: 1996
Model: Cherokee
Engine: 4.0L, CAI, Edelbrock Breather, Optima Yellowtop
I started doing the neutral shift thing last month as a result of seeing that I was getting 12mpg city. I calculate my fuel efficency every time I fill up now and I'm getting about 15-16 city just as a result of coasting in neutral.
There is nothing wrong with doing it and it really does no harm to your AW4. Chrysler actually recommends shifting from drive to neutral when using shift on the fly 4wd. I doubt a manufacturer would tell you to do something harmful to your vehicle lol. So don't be worried, you'll be fine!
There is nothing wrong with doing it and it really does no harm to your AW4. Chrysler actually recommends shifting from drive to neutral when using shift on the fly 4wd. I doubt a manufacturer would tell you to do something harmful to your vehicle lol. So don't be worried, you'll be fine!
01-16-2011 | 03:43 AM
#40
Junior Member
Joined: Jul 2009
Posts: 96
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From: Ireland
Year: 1995
Model: Cherokee
Engine: 4.0 H.O
A 25% decrease in fuel consumption seems a little optimistic to me.
Also regarding the rolling in neutral thing... yeah you may go further but 9/10 times you will use your brakes therefore negating any distance advantage you gain from rolling in neutral.
Also regarding the rolling in neutral thing... yeah you may go further but 9/10 times you will use your brakes therefore negating any distance advantage you gain from rolling in neutral.
01-16-2011 | 03:14 PM
#41
Seasoned Member
Joined: Nov 2010
Posts: 473
Likes: 2
From: Cincinnati, Ohio
Year: 2004
Model: Grand Cherokee
Engine: 4.0 I6
01-17-2011 | 12:04 AM
#42
Senior Member
Joined: Sep 2010
Posts: 905
Likes: 1
From: Llewellyn, PA
Year: 1998
Model: Cherokee
Engine: 4.0L I6
Unless your like my mother who drives way too fast, brakes way too hard, and her brakes only last for about 1200 miles. She also wears them down until her brakes grind and then she not only needs pads but new calipers also. Lesson to be learned from this, when the pads get low change them before you destroy your calipers
01-17-2011 | 12:30 AM
#43
Senior Member
Joined: Jan 2011
Posts: 627
Likes: 2
From: Bedford, Pa
Year: 2000
Model: Cherokee
Engine: 4.0
Originally Posted by breakthecycle128
Has yours ever just died? 125,000+ miles between my 2.5 and 4.0 and they never died while drifting in neutral (I did it all the time with the manual). Maybe I'm lucky, and of course anything could happen, so I sort of see your point. But getting to the question I don't believe that drifting in neutral creates any direct harm to the tranny, manual or standard.
01-17-2011 | 12:45 AM
#44
Senior Member
Joined: Sep 2010
Posts: 905
Likes: 1
From: Llewellyn, PA
Year: 1998
Model: Cherokee
Engine: 4.0L I6
I don't shift into N before going into/out of 4H, should I? I haven't had any issues yet.
01-17-2011 | 12:50 AM
#45
Senior Member
Joined: Jan 2011
Posts: 627
Likes: 2
From: Bedford, Pa
Year: 2000
Model: Cherokee
Engine: 4.0
Originally Posted by Griff94
I don't shift into N before going into/out of 4H, should I? I haven't had any issues yet.