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Unread 08-13-2010, 08:57 PM   #1
will21190
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coasting in neutral w/ a manual...good or bad for the engine

I have a 5 speed and was wondering if this would hurt the engine...im trying to save on gas, and i figured it woul help just a lil.

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Unread 08-13-2010, 09:01 PM   #2
Sweeney
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It won't hurt a thing.
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Unread 08-13-2010, 09:02 PM   #3
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lol
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Unread 08-13-2010, 09:02 PM   #4
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Originally Posted by Sweeney View Post
It won't hurt a thing.
x2 I do it a lot when im goin down a hill.
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Unread 08-13-2010, 09:10 PM   #5
adudenamedsean
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I was under the impression that coasting in gear actually saves more gas because while in neutral it requires fuel to keep the engine running. On the other hand, coasting in gear just uses the engines resistance and shuts off the fuel. Or am I totally off base here?
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Unread 08-13-2010, 09:17 PM   #6
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Originally Posted by adudenamedsean View Post
I was under the impression that coasting in gear actually saves more gas because while in neutral it requires fuel to keep the engine running. On the other hand, coasting in gear just uses the engines resistance and shuts off the fuel. Or am I totally off base here?
Turn the key off and see what it does.

OP; Coasting in neutral for short distances won't hurt anything.
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Unread 08-13-2010, 09:21 PM   #7
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Originally Posted by will21190 View Post
I have a 5 speed and was wondering if this would hurt the engine
No engine damage will occur from this.

im trying to save on gas, and i figured it woul help just a lil.
Not enough savings will be noticed to make it worth doing, so don't bother. See below.
Quote:
Originally Posted by adudenamedsean View Post
I was under the impression that coasting in gear actually saves more gas because while in neutral it requires fuel to keep the engine running. On the other hand, coasting in gear just uses the engines resistance and shuts off the fuel. Or am I totally off base here?
On fuel injected vehicles, the air fuel ratio is determined by the amount of air passing through the engine (along with many other factors) so as long as the RPMs are happening fuel will be provided.
Coasting out of gear or "free-wheeling" is a lousy habit to develop. Should the need to accelerate or decelerate suddenly happen you'll invariably struggle to figure out what gear to be in or how to quickly respond.

You should ALWAYS be in the correct gear for the speed of the vehicle, no exceptions.

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Unread 08-13-2010, 09:29 PM   #8
adudenamedsean
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Gotcha. Thanks for clearing that up, Max.
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Unread 08-13-2010, 09:31 PM   #9
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I've been driving vehicles with a standard tranny for nearly 40 yrs, and agree totally with Mean Max. Plus, engine-braking is a wonderful thing when trying to time traffic lights!

Here, at 4900 ft above sea level, on pure gas, 15-17 mpg combined city/highway in a 2001 5-speed, 4.0L TJ is easy.
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Unread 08-13-2010, 09:43 PM   #10
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Originally Posted by adudenamedsean View Post
On the other hand, coasting in gear just uses the engines resistance and shuts off the fuel. Or am I totally off base here?
Off base? yep...
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Unread 08-13-2010, 10:14 PM   #11
RUBtjICON
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My Jeep slows down when I put it in neutral. It wont coast/free wheel for chit.
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Unread 08-13-2010, 11:51 PM   #12
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Originally Posted by Knuckelhead View Post
Off base? yep...
That is odd because there was an article in car and driver or some other car magazine I read that too on that myth specifically. They had an engineer from Toyota say that any vehicle produced after 1995 would benefit most from being in gear because it would use 0 fuel to keep the engine alive and you need fuel to keep the engine at idle when coasting. I don't remember 100% what he said about carb engines, but I believe it was something to the effect of it using fuel proportional to the RPM of the engine.

Maybe that Toyota engineer was mistaken.

Anyway, the point about always being in the right gear is what I have learned and stick to. It was first taught to me by my dad many years before I started driving (when I was learning about how manual transmissions work and shifting), then reinforced by many others over the years.
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Unread 08-13-2010, 11:52 PM   #13
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Quote:
Originally Posted by LuckRider View Post
That is odd because there was an article in car and driver or some other car magazine I read that too on that myth specifically. They had an engineer from Toyota say that any vehicle produced after 1995 would benefit most from being in gear because it would use 0 fuel to keep the engine alive and you need fuel to keep the engine at idle when coasting. I don't remember 100% what he said about carb engines, but I believe it was something to the effect of it using fuel proportional to the RPM of the engine.

Maybe that Toyota engineer was mistaken.
See that's what I thought too I think I got it from that same article.
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Unread 08-14-2010, 12:14 AM   #14
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I was driving a 5 ton Dodge flatbed from Kamloops, BC to Vancouver and there was a looong stretch of road with a steep downhill. Even with manual 5 speeds and a 2 speed rear axle it had a top speed of 55 mph boot to the boards, so I put it in neutral for Mexican Overdrive (we were hauling an asphalt ripper for a D9 cat)
After about 3 miles of coasting, we discovered (the hard way) that a bolt had fallen out of the trans, and the lack of oil caused 2nd gear synchro to weld engaged.... at 70 mph. Ever ride a bucking bronco? Piece of cake compared to this ride! Quickly thinking, I jammed in the clutch and tried to shift (loads of clashing noises, but no synch) but it stopped bucking till I let the clutch out again.
I had to hold it in till we coasted all the way down to Merritt. We tried to break it loose, but gave up and started heading the rest of the way home. Almost to the top of the pass, the clutch blew up and I spent 3 1/2 hours with my foot on the brake, awaiting a tow truck big enough to handle the load (they sent a 1 ton, a 3 ton, then finally the semi hauler and IT was working hard on the trip home!)
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Unread 08-14-2010, 12:24 AM   #15
buddyfilek
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Think about it. If you take it out of gear and coast your Jeep idles i.e. uses gasoline. Leaving it in gear lets the momentum of the jeep keep the motor turning through the wheels. Beyond fuel consumption, you have to consider that without engine braking you use up more brakes and you aren't in complete control of the vehicle. Any driver worth their salt keeps it in gear unless they are at a dead stop.
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