Forget the late model Ford only argument as the test was performed on an early model Ford, GM, and a Toyota transmission also.
To refresh, with every vehicle except the '05 Mustang and the 95 Camry there was an engine restart if the key was turned back on within a few seconds.
If 4 or so seconds passed there was NO restart.
I did a test on the '05 Mustang and Camry which I did not post.
With the shifter in DRIVE the key could be turned off and instantly back on followed by an engine restart.
Even with a 10 second delay an engine restart would occur.
However, if the time frame was extended to 15 seconds there would be no restart.
If the shifter were placed in NEUTRAL first followed by quickly turning off the key and turning it back on and THEN dragging the shifter into DRIVE quickly then there would be no restart from the get-go.
This places those 2 vehicles in a slightly different situation than the others.
This leads to a question.
It’s commonly stated that an automatic transmission vehicle should never be towed with the drive wheels on the ground due to the risk of burning a transmission up due to an inoperative transmission oil pump.
So by the logic here, does this mean one could place the shifter in DRIVE and tow the vehicle clean across the country and back with drive wheels on the pavement and do so without harm since the logic here is that the oil pump in the transmission would be operative? Why or why not?
(Keep in mind that the speeds involved in those tests I performed varied from 30 to near 70 MPH and there were no restarts even at 60+ MPH)
The above statement “So by the logic here, does this mean one could place the shifter in DRIVE and tow the vehicle clean across the country and back with drive wheels on the pavement and do so without harm since the logic here is that the oil pump in the transmission would be operative? Why or why not?” is rediculous because in that senerio the engine would be dead and probably cause much harm. However in the case that I present, the engine is turning and so is the tranny and drive wheels.
Now the other statement “If the shifter were placed in NEUTRAL first followed by quickly turning off the key and turning it back on and THEN dragging the shifter into DRIVE quickly then there would be no restart from the get-go.” is equally stupid because in neutral there would be nothing turning the engine and we all agree that a dead engine with automatic cannot be started by pushing it.
How did you get grease under your fingernails or get busted lnuckles??
The only thing stupid here is someone trying to do something stupid just to prove a point.
I certainly hope you generate work for your local mechanic.
Please Man-up and tell your mechanic just exactly what you were doing, so he doesn’t waste time trying to determine the chain of events leading to a mechanical failure.
Olderwrench, when I create a problem with my transmission, I will come on here and address a post directly to you. Going wownhill with the ign OFF (in my van) is little different than having the ign ON. I am my own mechanic!!
You don’t think it is stupid to drag a car across the country in Drive??
You don’t think it is stupid to coast downhill in neutral then turn ON the ign and put it in drive and expect it to start? (Not unless it is 45 to 50 years old.)
Have you read the posts on here testifying that after coasting in Drive for several seconds then turning on the ign and the engine fires right up?? That means the engine has been turning all the time. NOW I know this doesn’t work on many transmissins, but it does on mine and several others.
the question was “can a torque converter reverse drive an engine.” The term “reverse drive” was not my term, but used by the most respected transmission man on Car Talk, who said it would never happen.
If it will make you feel any better I will back out of this post and any post you create in the future. Even the simplest of questions to you have not only received no answer at all but I’ve come to the distinct conclusion that you are not even comprehending anything I’ve said.
Based on your prior comment to me about not using any long words such as “ludicrous” to you I can no longer converse in 1 or 2 syllable words combined with a series of caveman grunts. I would say adios but that’s one of those annoying 3 syllable words you seem to take offense to so I’ll just leave it at gud by.
Yeah, it seems that you haven’t comrpehended anything I have said.
The question was, “can a torque converter reverse drive an engine?” Answer: Yes it can as several people have and myself have proved it. We just can’t prove it to some guys on here.
Here is some of the comments that confirm what I have been saying:
An automatic transmission will reverse drive an engine. You can push start a vehicle with an automatic transmission. I’ve done it many times. Only with an automatic transmission the vehicle has be going 30-35 MPH in order for it to work.
Tester
Tranny needs a rear pump for this to work…But lots of older cars HAD rear pumps just for this reason…Torque converters, fluid couplers with a stator, will indeed reverse drive to a certain extent…not very efficient but they WILL transmit torque in either direction…
Simpler test - go down a hill in N, then in D with no gas. Big difference = engine braking = engine being spun by the torque converter.
You cannot push start a modern vehicle, as the transmission has no rear pump to generate fluid pressure and engage the transmission’s clutches. On some older vehicles <1965, you can.
However, the transmission will ‘drive’ the engine. If it couldn’t, then you couldn’t use a lower gear for engine braking, such as when descending a hill.
Flag comment as inappropriate
So long as you left it in gear and were going fast enough, turning the key off does not stop the engine from spinning…no matter the type of auto. If the engine spins, the front pump spins and the clutch packs remain pressureized
1
2
3
4
5
The answer is YES if the transmission is already engaged, you don’t put it into neutral and you don’t slow down to the point that the so-called “reverse drive” causes the engine to stall…yes the literal use of the word stall…stop spinning regardless of cause. I’m betting that would occur somewhere between 10 to 20 mph. Go ahead, give it a try.
Um, I believe you’re incorrect. I’ve had many vehicles over the years that didn’t even HAVE a lockup TC, and you could still initiate engine braking by downshifting the automatic to a lower gear. (or just watch the tach rise momentarily on each downshift)
If the TC could not transmit torque both ways, engine braking would be impossible. It may be more efficient transmitting torque from the engine to the transmission, instead of the other way, due to the turbine design, but it still transmits torque.
All 3 of our cars have automatic transmissions and tachometers. When traveling (say) 55 mph and I see a light turn red up ahead I immediately take my foot off the gas and start to coast. I notice that the rpm’s continue to hover around 2000 even tho’ my foots off the gas
I am a Master ASE Tech with 37 years experience. I overhaul automatic transmissions. I don’t believe in abusing a device that was not meant to be used in such manner.
80% of vehicle repair is owner induced.
What are your professional mechanical qualifications? I don’t consider a person who fixes a leaky faucet a plumber. How many years have you worked “The Line”?
I have similar credentials: Master heavy truck and master auto. I let them expire long ago after getting out of the repair and into the engineering (industrial controls) back in '98. Back then, I did my several hundred overhauls of the Ford auto of the time…E4OD, C6, A4LD, AXOD, AXODE, AX4S, ATX, AOD, AODE, 470RW and 4R100 and a couple of the Mazda ones they put in the newer Escorts…forgot what its called. For the rear drivers, I could disassemble, evaluate and write out the complete part numbers I needed for the thing…Yea, I did them enough that I knew the complete part number for most every gasket, snap ring, gear and whatever else…pretty sick but it made it convenient to just drop a list at the parts counter and not have to muttle around on microfilm for two hours. Anyhow, at that level of experience, you can more or less “feel” what’s wrong w/o any shop manual. That also says something for the quality of those transmissions…not very good on the late 80’s and early 90s. Ford managed to keep thier own design right through. Chrysler and GM gave up and subbed out the heavier transmissions…they no longer make them at all.
Oh, and BTW, it’s just a piece of machinery. It has no feelings. Do what you want with it. Hell, its belongs to you. Take it out and take it apart if you’ve got the time. The premise of the original question seems rather insignificant.
There is one thing I can say if question is meant to imply that you can start the engine with the transmission. The answer is absolutely never, no, no-way,no-how…no matter the forward speed. You will not find a modern, planetary-based auto that does that. The dual shaft autos that are just coming out may be different as perhaps they have electric pumps…I don’t knwow. I do believe that planet based autos are doomed and will be replaced by dual shaft(ZF has trashed Allison in the heavy truck market on this already. Other than that, most drives will be elctric servo motor.
I have never said that you could start the engine with the transmission. I know that for several years this was impossible. However, with the engine running and going 20 to 80 MPH, I can turn off the ignition and the enine will keep turning and the front pump keeps turning and the clutches continue to hold annd the engine will hold back the vehicle until it slows down enough that the converter no longer can turn the engine and it will die. I don’t know just how slow that may be. That is because, and you know this, the converter slips more pushing the engine than it does with the engine pushing the converter. It dosen’t hold back as much as it holds with the engine doing the pulling or pushing. I know that you know this, I am just letting you know that I also know this. Now with the ign OFF many cars will not do as mine will, but many will. Mine is a '96 Dodge V8 4 speed automatic.
In your humble opinion, will a torque ever “reverse drive” an engine? That is the question. The term “reverse drive” is not mine but one that Transman came up with. A simple yes or no will suffice. All other explainations are immaterial.
OK. Humbly. The torque converter will drive the engine but only in the dircetion it normally spins. The reverse part of that needs to be nixxed…it has an ambiguity that also implies it will drive the engine backwards. That will never happen. Many large electrical motors in industrial equipment also use torque converters. E.G. cement/concrete mixers. They use them for increased starting torque and as a slip coupling if the mixer is jammed. If the operator doesn’t take care of that and just lets the converter stall against the mixer, there is a lead plug that will melt and allow the fluid to spill out, rendering the fluid coupling uncoupled and the 40 or so HP electric motor happily spinning unloaded and safe from overload. Sorry to throw that example in there but I think it may be helpful to see that torque converters are used in many other contexts than automatic automotive transmissions. Would the mixer drive the electric motor? Yes. If you turn the electricty to the motor off, then the converter will drive the motor for a short time…at least that removes the complexity of gears and valve bodies.
I told you that the term “Reverse Drive” was not my invention. Transman, came up wit it. I assumed it meant just the opposite of the engine driving the converter. Now someone has to come up and throw another derailment in the argument.
Let me say all I have said, or meant to say is this! A torque converter will turn the engine in some vehicles. I know that you cannot push start a modern car with an automatic. Evidently many cars will only do this for a short time, a few seconds. My Dodge V8 4 speed transmission will do it even with the ignition off for at least 24 seconds. I have never tried it longer because I haven’t found a long enough hill. The engine continues to turn, brakes and steering continue to work and when I turn the ignition ON the engine fires up (without using the starter}
This is the point I have tried to get across. And some of you guys think I am crazy.
EllyEllis:
The sad part of reading through this thread is it could have been a productive and interesting discussion, if you had only approached it differently and didn’t keep pulling it into the gutter.
I think the sad part is with several men testifying that a torque converter can indeed drive an engine, that some knuckleheads still deny it, and imply that I know nothing about what I am talking. In fact, I was told that very thing. (on a different thread, “turning off your car at 55”
I know now that if I ever need any information, I surely won’t ask Car Talk!
lawsaga, with all that experience and knowledge then you know full well that a converter can drive the ehgine. Why don’t you say so and we will be on the same page.
As said before, I have repeatedly done this in my '88 Dakota, most recently for a (counted) 30 seconds, exiting a freeway on a downhill. Leave it in D, turn the key back 1 notch (to ACC), wait 1/2 min, turn key back to IGN, drive away.
As stated before, if the TC couldn’t “reverse drive” the engine, there’d be no point to downshifting an AT for descents.
I’m rather flummoxed by ok4450’s insistence that this isn’t happening. Either he believes that there are 2 separate people so invested in a pet theory that they’re making up experimental data, or he’s in “doubting Thomas” mode, and won’t believe any result he didn’t personally observe.
Remember, “absence of evidence is not evidence of absence.” Just because one car (or many cars) fail this test, it does not follow that it is impossible to occur; yet, if one or more cars behave in this manner, it DOES prove possibility.