Regarding the comment about the oil pump in the transmission not pushing fluid, resulting in premature transmission failure, this statement is indeed true. While an engine does have an oil pump, a transmission also has an oil pump. True, it could also be referred to as a “transmission fluid pump,” but it’s all the same. The only automatic transmission that will put up with being coasted (or towed) all the time is a Powerglide two speed since it has the oil pump attached to the output shaft, so the fluid is flowing any time the wheels are turning. Therefore, unless the OP has a Powerglide or a manual transmission, automatic transmission damage is an additional concern.
Regarding your question about harming the electronics by having the ignition on, they couldn’t care less. The key is on when you’re driving the car, also. It won’t hurt them. Your starter will likely suffer gravely from this behavior, though, among other things.
I still have a hard time believing you can get that much of an increase by turning the engine off during a time when a vehicle is using the least fuel possible (zero fuel in late model cars). I can’t help but think that your light-foot for the rest of your driving is coming into play here. I guess we’ll agree to disagree.
Your other comment about a transmission oil pump is incorrect. The transmission does have it’s own front oil pump which is driven off the engine turning. If the engine isn’t turning, the trans oil pump isn’t turning. Just ask any tow truck driver about why they don’t tow a vehicle with the drive wheels on the ground.
Boy are you talking out your tailpipe. Whether you call it transmission oil or transmission fluid, automatic transmissions have pumps, and coasting, even in neutral can damage most of these transmissions because of the lack of fluid circulation.
If I recall correctly, didn’t all automatic transmissions built up through the 1965-67 timeframe have both front and rear pumps?
I worked in a gas station then. We learned the hard way that car manufactures no longer used a rear pump (driven off the wheels). We had always successfully been able to push start automatics. We began to get a few that we would push and push (for several blocks) and they just wouldn’t start. It was then we learned about the cost-saving step of no longer including a rear pump.
Of course, this thread probably annoyed the OP so much that we’ll probably never know whether it is an auto or manual. I’m sure tho that this wasn’t the OP’s question either.
I’m not sure if they did or not. I know the Powerglides did. I know the Turbo Hydramatics and TorqueFlites I’m used to dealing with do not, and I believe they were largely unchanged since they came out in the sixties. Powerglide is the only automatic I’m aware of that had front and rear pumps.
To Ron-man: I thought I was pretty clear that I was referring to automatic transmissions in the above post and sincerely hope I did not create any confusion by omitting one adjective from my post. The specific type of transmission is cited throughout the rest of my post. The lack of a fluid pump in a manual transmission is probably considered common knowledge in the automotive repair world, as it is a completely mechanical device.
harming the electronics by having the ignition on, they couldn’t care less.
I’m not completely convinced of that. Probably not a problem for a limited duration as the OP states, but I believe it could be a problem for certain designs if left on for extended periods. What I’m thinking about is certain ignition system designs that are not meant to handle 100% duty cycle power dissipation. For example, in a simple ignition circuit with an ignitor and ignition coil, the ECM provides a signal to the ignitor to disable the primary circuit (generating spark energy) when it receives an RPM input signal pulse from the pickup coil. If that signal is not running, then the primary side is always ON and dissipating power in the coil and ignitor. Under normal use, it’s not going to sit in this condition for extended periods and so the parts are not designed to handle it. Even if it can handle it for short periods, it might suffer some kind of cumulative effect, kinda like eating burgers every day for 10 years. It doesn’t kill you immediately but takes a toll each time you do it
If there’s something wrong with this logic, I’m sure someone will be quick to point it out…
Yes, you could melt the coil and the ignition modules in early 80s Fords by doing this. I strongly suspect that this is no longer a problem for any car new enough to have electronic distributor-less ignition.
Honestly, I think a lot of these ‘hypermiling’ techniques are ridiculous. Coasting with the engine on and the tranny in gear uses ZERO gas in a late model car. I do a lot of driving, and it is very rare to get into a situation where I could coast a significant distance in neutral with the engine off. I wouldn’t do this anyway as I think that restarting the engine (properly, without over revving the starter pinion) and putting the car back in gear creates a distraction, and most of us have enough of those already. Just my opinion, but being trained as a professional driver, I do think my opinion has some validity. And yes, I do wring pretty good mileage out of my cars.
Not using a mech dist just means the pickup signal is coming from the crank or cam sensor. Still has to perform same basic functions. As pointed out people inclined toward these extreme practices probably have the most basic model of car. And the trend has been to make everything as cheaply as possible so designs get more marginal every year. So I’m not convinced the issue doesn’t exist anymore but who knows, you could be right.
