By this logic, it means that one can take a socket and breakover, place it on the harmonic balancer bolt, and the engine cannot be rotated by hand due to the drive wheels locking to the pavement.
Not that I agree with that logic; just sayin’…
This here shows just how stupid you are. There is a lot of difference in a stopped engine and transmission than a moving vehicle in Drive and the engine running. Hell no turning the engine with a wrench will not turn the power wheels. Don’t you know that when you stop, the engine keeps turning although the wheels have stopped?
It might be that as long as the engine is turning, the trans is being lubricated whether the engine is on or off. I can’t say, don’t know. But towing an automatic with the wheels turning and the engine off will burn up a transmission I believe.
Read this carefully, so you will no longer be confused.
For some reason, Transman said that an automatic transmission could in no way keep an engine turning while slowing down or coasting. I said that Mine would. He said that he was a Professional Mechanic and it could not. I took my '96 Dodge van V8 Automatic to a hill I use a lot and turned the ignition off and I did not loose power steering or brakes, and 40 seconds later, turned the ignition on and resumed on down the road about 2 miles to my destination. Transman got pretty ugly with me for disputing him. Frankly, I don’t care much for the guy.
Read what chunkyazian Duct Tape Specialist has to say about it.
August 26 edited August 26
An older, hydraulically controlled automatic might drive the engine when the ignition is shut off at speed. The hydraulic computer works as long as the transmission is driving the engine fast enough to power the oil pump.
Hmmm, I gotta say that I was going 70 mph in my Riviera on the freeway when the crank sensor went and lost all power. I had to muscle it to the side of the road so quite sure the transmission was not turning the engine over yet. It was just dead dead.
What say we keep the discussion to the car-related parts, and not impugn forum members who 1) have a better reputation for expertise than we do and 2) aren’t here to defend themselves?
Well, EllyEllis impugned me on page 4 by stating “just shows how stupid you are”.
Again, just like earlier in this thread and the one from months ago I’ll ask EllyEllis to explain it to the dolt. (me)
Give me a technical explanation of how a direct drive is maintained from crankshaft to drive tire contact on the pavement OR;
Provide a link explaining it to me.
I’m stupid and with no clue. With your help maybe the light switch will flip on.
When you clue me in I’ll also let my friend who has 40 years in overhauling transmissions know because he was curious too. Apparently he’s as dumb as me…
1:27PM One more time I say, "the argument was not about “push starting”
If you are rolling down a hill with the ignition off, but the vehicle’s automatic transmission in a forward range and the engine is turning, how is this different than pushing the car at the same speed as rolling down the hill with the ignition off?
I don’t think an automatic transmission completely free wheels when coasting, so it must supply some power back to the engine. I did once start a 1952 Dodge with the “Gyromatic” semi-automatic transmission by rolling down a steep hill with the transmission in low range. At the same time my parents owned this Dodge, they also owned a 1954 Buick with a manual transmission. The Buick did have more “engine braking” than the Dodge and I could push the car by hand with the shift in neutral, jump in and pop the clutch and the engine would start. Now I know that there was slippage in the fluid coupling in the Gyromatic transmission of the Dodge and there is slippage in the torque convertor of modern automatic transmission. However, the automatic transmission of modern cars has the lock-up feature. If the lockup is engaged, I can see where the drive wheels could keep the engine turning over with the ignition off.
I have had the engine stall on my 1971 Ford Maverick while turning a corner at low speeds and I did lose the power steering, so the engine obviously wasn’t turning. ( Maybe this is a good argument for electrically assisted power steering). I think that there must be some power transmitted back to the engine through the transmission at higher speeds–enough to keep the engine turning, but not at lower speeds.
Triedaq Senior Grease Monkey
If you are rolling down a hill with the ignition off, but the vehicle’s automatic transmission in a forward range and the engine is turning, how is this different than pushing the car at the same speed as rolling down the hill with the ignition off?
I think you are talking about pushing a car who’s engine is still, in order to start the engine.
The difference is in the first example, the car is moving and the engine and transmission are both working. In the second example, the engine and transmission are not moving.
@ok4450 yeah, actually my comments were pretty much directed at Elly. I’ve been known to hold some legendary grudges but. . . Wow. Just let it go, especially when the person you’re still warring with hasn’t been seen in months.
Well, I am going to let this go, several guys have agreed with me but the others refuse to believe them or I. Some are too stupid to understand what I have been talking. AS they say, “you can’t fix stupid.” The fact is , Some automatics will drive the engine if going forward at city speeds with the engine off or on. This is what all this was about.
Stop calling people stupid. It’s not nice, and it’s against the board rules:
3.1 (b) Be courteous. You agree that you will not threaten or verbally abuse other Service users, use defamatory language, or deliberately disrupt discussions with repetitive messages, meaningless messages or “spam.”
3.1 (d) Debate, but don’t attack. In a community full of opinions and preferences, people always disagree. CarTalk.com encourages active discussions and welcomes heated debate on the Service. But personal attacks are a direct violation of these Terms of Service and are grounds for immediate and permanent suspension of access to all or part of the Service.
If you are rolling down a hill with the ignition off, but the vehicle's automatic transmission in a forward range and the engine is turning, how is this different than pushing the car at the same speed as rolling down the hill with the ignition off?
It’s a system that exhibits hysteresis: the properties of the system change in different configurations, so what is true in one, is not necessarily true in another.
Let me give you an example using a slightly simpler system exhibiting hysteresis…one simple enough that I actually “get” it. A scooter-style centrifugal clutch could NEVER be bump-started: there’s no connection between input and output; I don’t care if you’re doing 130. HOWEVER…if you get the engine up to a speed where the clutch engages, then cut the power on a sufficiently steep downhill–you can remain in gear as long as you have a hill to descend.
I have taken the “transmission challenge” thrice: my 1988 Dodge Dakota remained up on RPM for as much as 30 seconds; my 1992 Olds Cutlass would have the engine stop within 2 seconds, no matter what I tried; my 2008 Cobalt actually downshifts!
I’m not really all that knowledgeable about ATs; if I had to make a guess, I think it has to do with what happens to the Lockup Torque Converter when you cut power. If the TC remains engaged, I can see how the AT continues to spin the engine.
I was hanging back because when there are longstanding forum members who get a little heated, I like to give people a chance to sort it out among themselves.
This thread started as a tribute of sorts to somebody who isn’t around anymore, and it evolved into a tranny discussion (kind of a fitting tribute to a transmission guy, yes?) and now you’ve managed to turn it into something mean-spirited and fractious. @EllyEllis, please stop with the name-calling. @shadowfax cited the applicable forum rules, because simply being asked to stop didn’t work.
3.1 (d) Debate, but don’t attack. In a community full of opinions and preferences, people always disagree.
Yes people have the right to disagree about debatable subjects, but 2X2 = 4 and 4x4 = 16 and that is not debatable. My '96 Dodge 1/4 Van would keep the engine turning going downhill until it slowed to nearly stopped, with the ignition on or off, and that is not debatable and not disagreeable. It is not open to opinions, preferences.
@meanjoe75fan–Your explanation clears it up for me. In the example that EllyEllis gave about turning off the ignition at the top of the hill and then turning it back on and the engine restarting instantly, this makes sense with your example with the centrifugal clutch. However, had he shifted into neutral, turned off the engine, and then shifted into Drive or a forward range on the automatic transmission, the engine would not turn over no matter how fast he was rolling down the hill.
Thanks for your post.
@meanjoe75fan–I was going to test your illustration of the centrifugal clutch. My rototiller has a centrifugal clutch and I wanted Mrs. Triedaq to spin the tines to see if it would crank the engine. However, she doesn’t want to cooperate with this experiment.
When I think about the illustration in my owner’s manual for the 1948 Dodge I once owned for the way the fluid coupling worked, one was to picture two identical electric fans facing each other. One fan was switched on and the other fan not powered. The fan that was not turned on would turn approximately as fast as the fan that was powered. The transmitting medium in the fluid coupling was oil instead of air, but the principle was the same. The torque convertor is similar to the fluid coupling, except that it multiplies the torque.
Therefore, it must be in the transmission unit itself that serves as the centrifugal clutch so that the power from the rear wheels will not turn the engine if the engine is not already spinning over.
EllyEllis, go to the top of that hill, stop the van, turn off the ignition and then let the van roll down the hill in gear. Let us know if the engine turns then. So far your example is apples and oranges.
Personally I don’t care who is right on this debate, but if you want to make a case, you must have ALL the parameters the same, you cannot change two parameters and get a valid result (unless you know how to set up a Taguchi array).