NO Damage to auto transmission by EOC
 

I have an '07 Toyota Tundra and am getting 21-22 MPG (combined -- 85% highway driving) by using basic hypermiling techniques. The sticker said 16/20.

I'm looking to do some EOC, but WAS concerned about damage to the automatic transmission. I talked to the service department at the Toyota dealership, and the guy said I will do NO damage to the transmission by coasting with the engine off for a short period of time (ex. down a hill) or by shifting in and out of neutral.

As far as EOC goes, he agreed that, since the engine is off, the transmission isn't doing anything. There's no damage to be done.

Does anyone have any contrary information? People talk a lot, but often know very little about what they are talking about. It's really amazing. If anyone KNOWS that this information I got is wrong, by all means, speak up. I really want to try the EOC, but don't want to fry a $4,000 transmission in the process.

Thanks in advance for any input you may have.

Scott

Welcome to the site ScottC33.

The same rule goes for all vehicles. Check your owners manual to see if your vehicle can be flat towed or not.

Since you are moving, and your wheels are rotating, and the wheels are directly connected to parts of the transmission which are then also rotating, parts of the transmission are moving and it is possible they are not going to get lubricated properly with the engine off.

Ding ding ding ding ding!!!
That's the best answer I've ever heard regarding this issue. Seems so obvious now. :P

The most comprehensive list I've seen for vehicles that CAN be flat towed is Motorhome Magazine's towing guide:

Dinghy Towing Basics

The Tundra is NOT on the list for 2007 vehicles.

I know only time and repair bills wil tell, but EOC vs Flat tow are to completely different subjects. Other than the extreme EOC'ers here I couldn't imagine anyone EOCing for more than a mile at a time and if they do they probably have manual tranny's.

I for one, EOC an Automatic also, the longest stretch I have EOC'd is 3/4 of a mile, I have no hills here. Therefore I have convinced myself that with synthetic oil in the tranny pan, there is enough sloshing around the tranny to keep it safe for short distances.

But again, that is an untested opinion, but if I'm wrong then I will simply switch to a manual tranny and be done with it ..

Same here, I don't EOC on the highway though, glides are too short.

I only EOC in town... Gotten out and pushed too:turtle:

I've never seen a manual say that coasting in neutral with the engine on will void a warranty. If people are concerned about EOC, they can still use neutral. It won't be quite as efficient, but it will be close. I will continue to EOC, however.

I EOC for more than a mile (1.2 miles) at least once a day.

I know for a fact that Chyrsler trannies when coasting in neutral with the engine shut off can be ruined fairly quickly if coastibg at over 25 mph.....the engine must be runing for the pump to be circulating the fluid....if you see one being flat towed they have hooked up an electrical pump to not have any troubles. The longest EOC I did was about8 miles at one time....leaving Rock City.

And you won't because;
-It's impossible to prove a failure as a result of Coasting
-Until someone gets hurt doing it, sues and wins, you won't see it printed.

The best example of this is the customer who bought an RV, set the cruise control and left the wheel. Obviously crashed, then sued the RV company and won because it didn't say she had to stay behind the wheel while in cruise control. It says it now ... LOL

I used to EOC in an old Metro before it finally bit the dust. The auto tranny was crapped out and you had to shift using the gear shifter. Simply putting it in D would not work. Sometimes it would start off in 2nd gear and do 0 - 60 in about 30 seconds. Anyway, I was hoping I could kill it off for good using EOC... nope. I think EOC is fine in automatic as long as you're not coasting for extreme distances. I would be weary of distances over a mile, but distances less than that not so much. From my understanding, the transmission is not getting vital oil and lubricants during when being flat towed. Unless you're coasting for extremely long distances I doubt you would have enough time to burn up the transmission.

Of course my opinion is untested as well.... just don't come knocking on my door if your tranny bites the dust.

Uh is this for towing a Tundra behind an RV, or towing an RV behind a Tundra? :D

I wonder if anyone ever uses the towed vehicle to add power for accelerating? Ie, when pulling into traffic or going up a hill, the towed vehicle starts up and adds power, then shuts off the engine.

In theory, this would allow one to use a smaller more efficient engine on the towing vehicle.

That would be an awesome idea for RV'ers, the problem is that the dingy would have to be automatic and probably the size of a full size truck in order to move an rv from 0- whatever. I can't see a yaris making much ground on a full size bus RV ..LOL

Then of course you have 99.9 percent of all automatic tranny's can't be towed behind an RV.

Good point - the wheels on the towed vehicle would need a freewheel/ratchet installed - it can then push forward, but when turned off, the transmission wouldn't move.

Would be useful even if the towed vehicle was just accelerating its own weight.

I tried EOCing in my 2005 Chevy Cobalt once, and despite it being on that dinghy towable list, I won't be trying it again. I was on a long down-sloping stretch of country road with nobody around, so I popped it into neutral and shut the engine off. I was rolling at about 40mph, brakes and steering felt ok, so I kept going until I got to the stop sign at the bottom of the hill. I kicked the engine back on so I had my power brakes back and came to a stop at the sign.

When I pulled away from the stop the car was acting like a manual trans. with very poor clutch work. Shifts were hard and jerky, and coming to a stop the RPMs would drop to around 500 shaking the whole car before it popped out of gear. It did this the rest of the way home. The car sat for about 30 minutes before I needed it again and the problem was gone, I think it just drained too much fluid from the torque converter, and it never got a chance to refill, or something. I don't know all that much about transmissions. It hasn't been a problem since then (3 months).

How long did you EOC adrive? Good to hear nothing bad happened permanently.

It was probably .75-1 mile tops.

Your service manager probably wants your money when you burn up the tranny.

The tranny gets it's lubrication pumped from the spinning of the engine. When you put it in N and shut off the engine, the drive shaft is still spinning gears inside the tranny. This is why in manuals they say the car should never be towed above 25-30 mph for short distances in N with out the drive shaft pulled out.

Leaving the engine on and coasting in my '90 Firebird along with other driving style changes shot from an average 12 mpg to 20 mpg. Keep the engine on and keep cash in your pocket.

You guys are freakin' me out about the EOC. :eek:

I read a couple of days ago that Ford's next version of - I think it was the Fusion - will be flat-towed capable.

Okay... my 2004 Nissan frontier 4x4 is on the list of cars that can be flat towed, but only when the 4wd selector switch (in my case, shifter) is in "neutral"... so... yeah... i have to shift through "4wd Hi" and "4wd Lo" to get to the "N" on the shifter, and i dont think that it has shift-on the fly capabilities... and even if it did i wouldnt want to go through them going ~50.

any ideas?

I have EOC-ed in neutral (the neutral on the automatic tranny, not the 4wd selector) in the truck before, but i got immediately nailed with the consequences.. after doing it three times, the truck wouldn't start when i turned the key back, so i had to coast it to the side of the road and get my friends to come give me a jump... and the battery is a little over a year and a half old, with no extreme usage of it. i havent EOC the truck since then

That does sound VERY strange! Prolly pissed off something computer-wise.
Lack of fluid in the torque converter would just not want to go.

Check to find out if your 4WD system is vacuum actuated or electronically actuated... if it's either, it would be VERY easy to make a switching system to put it in neutral without shifting the lever at all.

That sounds like my car after disconnecting the battery. A few drives later it all gets back to normal. If it did that after EOCing, I wouldn't do it again either.

The only experience i had with EOC an Auto was with a rental car. Comming down off a bridge to an exit - shift to N - keyed car off - then back on ( just like the nissan) - engine dies and i coasted probably about 1 mile at about 60 MPH.
near the end i could smell the fluid cooking so i quickly restarted the car - exited and drove on site streets to keep overall speeds down.
Maybe it was the car ( Fusion V6) maybe it was the Speed ( i was at 60) or something else. But i convinced myself NOT to try it again.

Steve

*bangs head* Dammit! Should have got the insurance!

Yeah i just looked, my car says NO to flat towing so i guess no ECO for me, but I don't mind, I like zipping around in neutral all day anyways and not having to start my car over and over.

I started checking out some mild EOC in Cara... never more than a few hundred feet, always at low speed (< 30 MPH), while coming to a stop at a redlight or something.

So far, based solely on observation, I think I've actually gotten worse MPG's. I'm only going on my average mileage by the time I get to 1/2 tank on the gauge, which isn't wholly accurate, but so far it's off by about 50 miles.

If I had to chance a guess, I'd say I'm either getting close to the same old 27.5 ish, or maybe a little less.

Anyone care to submit some analysis of the situation?

Which vehicle, the GP or the van? The GP's, and anything with the 3800, hate EOC with a passion. The transmission isn't designed for it, and there are a lot of systems that get stopped along with the engine when you key-off. I hear the ABS doing a self-check every single time mine starts, so I don't stop the engine for anything under 30 seconds.

My fiancee's Honda Fit AT can be flat-towed. I'm looking forward to trying EOC in that car. If she lets me.

Not with Granny, with Cara... the first time I thought about trying it with Granny, we found out that she's not the most reliable starter... solenoid problem that I don't care to fix.

Granny also has a problem with her "Range selector switch" and some EGR issues, neither of which, again, do I care about.

I didn't read the whole thread, but in case it hasn't been mentioned, many automatic transmissions run the oil pumps off of the input shaft, so if the engine isnt running the transmission isn't getting any lubrication. BMW's are designed this way. Doing this for any period of time with a transmission like that will leave you stranded sooner or later. Another thing to consider is the additional wear induced by shifting in and out of gear. That wont leave you stranded unless your transmission was already on its last legs, but it will cause additional wear and premature failure.

You use so little fuel when coasting anyway, especially with newer cars which cut fuel entirely during engine braking, I doubt you'll see any measurable benefits.

Shifting in and out of gear doesn't harm much as long as the engine's running.

As far as measurable benefits, my ScanGauge shoots up ~20-30 mpg when neutral coasting with the engine on. And I coast further since the engine isn't slowing the rotation of the moving parts in the transmission. My engine RPM's during a coast with the transmission engaged are about 900-1000, vs. 650 at warm idle. Plus my old-school pushrod V6 doesn't have any sort of fuel cut, only a drop back to idle consumption.

I EOCed in my automatic tranny Corolla.. for a while on the highway and not on highway... it was bad news. i mean the parts are still turning but there's no lubrication.. in the end, i was lucky to have gotten a maintenance check anyway, and i had no transmission damage, BUT my tranny oil was so fried it wasn't even the same color. i had it replaced and haven't used EOC since. btw, i researched after, and my car cannot be flat-towed

On a site about DIY EVs, there was a discussion about using a cheap fuel pump as a pump to maintain transmission fluid pressures in an automatic for EV use. Maybe someone can try that idea?

EOC in neutral with a manual transmission is fine, right? Or do manual transmissions have oil pumps running off the engine too?

It's not fine with all transmissions, it can still be damaging, depending on which shaft is immersed in oil.

As long as the output shaft of the transmission is the one that's slinging lube all over, or if it's a pressurized oiling system, with either an electronic pump, or a output-side pump, you're fine.

If you're unlucky enough to have a tranny w/ the input shaft slinging oil, you're probably still good for awhile, since it's just gear friction you're worrying about... The viscosity of the oil will make it hang out for a good while before it actually needs to be exchanged for fresh oil to cool and lube the bearings/gear faces, but there are claims out there that it can damage your transmission if you have an input-fed oil system, in a manual transmission.

If you have a shift on the fly 4wd system, put the xfer case in neutral, not the transmission. Just about all vehicles with SOTF 4WD can be flat towed as long as you shift the xfer case into neutral. While the xfer case is in neutral, the transmission can be put in any gear there is, since no part of it is moving anymore.

This won't work on older stick-shift xfer cases, though, as they're not even close to synchronized, and won't go back out of neutral until you come to a complete stop. (Unless you're really good at gear/speed matching.)