[fyrffytr1]

This is a general question about automatic transmissions. A friend of mine told me that when a transmission is in neutral the pump doesn't push fluid through the cooling lines and the trans could burn up. I said the pump starts working when you crank the vehicle up and only stops when the vehicle is shut off.
Does the pump push it with more pressure the higher the engine rpm or is it pretty much the same throughout the RPM range?

[SRR]

Your friend is wrong.

[Sirrotica]

Tell your buddy to put his car in neutral and disconnect the cooling line, then start the car up. I bet he changes his mind in about 1/2 a second....................

As the RPM increases so does the volume and pressure.

He could be talking about towing a car in neutral with the engine not running, there is no circulation in almost all automatics. A few of the really old ones had rear pumps, and could be push started, no late model cars that I know of have rear pumps.

[Dens71TA]

Many Chrysler automatic transmissions don't pump fluid in PARK but I've never heard of an automatic that doesn't move fluid in neutral.

[Scott Thelander]

Brad
I just about choked till I was blue on my sandwitch

exactly !! thats how I change the fluid on my trucks .... fire em up and pump em into a 'milk jug till they spit
add fluid ... repeat ....

yah I bet he will change his mind !!

[Sirrotica]

Originally Posted by Scott Thelander

Brad
I just about choked till I was blue on my sandwitch

exactly !! thats how I change the fluid on my trucks .... fire em up and pump em into a 'milk jug till they spit
add fluid ... repeat ....

yah I bet he will change his mind !!

[fyrffytr1]

Thanks for the replies. I was talking about a vehicle being driven, not towed. While on the subject here's another question; does it hurt to put a vehicle in neutral when going down hill at cruising speed say 55-65mph?

[Sirrotica]

Originally Posted by fyrffytr1

Thanks for the replies. I was talking about a vehicle being driven, not towed. While on the subject here's another question; does it hurt to put a vehicle in neutral when going down hill at cruising speed say 55-65mph?

I do it all the time, I have been for many years, never had any problem in my 05 GTO, 4L60E 140,000 miles, 1993 k3500 dually, 4L80E, 265,000 miles. 1999 Grand Prix, 4T60E, 108,000 miles. All original transmissions. As long as the engine is idling, the parts have fluid flowing to them keeping them lubricated.

[fyrffytr1]

Again, thanks for the reply.

[66sprint6]

Originally Posted by fyrffytr1

Thanks for the replies. I was talking about a vehicle being driven, not towed. While on the subject here's another question; does it hurt to put a vehicle in neutral when going down hill at cruising speed say 55-65mph?

Mexican Overdrive.

[TAKerry]

Originally Posted by Sirrotica

I do it all the time, I have been for many years, never had any problem in my 05 GTO, 4L60E 140,000 miles, 1993 k3500 dually, 4L80E, 265,000 miles. 1999 Grand Prix, 4T60E, 108,000 miles. All original transmissions. As long as the engine is idling, the parts have fluid flowing to them keeping them lubricated.

Why would you do that? When im moving forward i put the car in D and go. P when i park. I have a buddy that was a truck driver. He has a unique way of driving an auto trans. Puts it in low everytime he starts and shifts through the gears. I thought he was going to kill the thing but he swears he has always drove that way with on ill effects.

[Ben M.]

Originally Posted by fyrffytr1

does it hurt to put a vehicle in neutral when going down hill at cruising speed say 55-65mph?

The only issue I'm aware of is if you need to make an evasive move due to something in the road or some other dumb#)) in your way, having it in neutral makes it one more move you have to remember to correct before getting out of the way. Beyond that, I don't think so. I did it for years in a TH400 car and it never had an issue.

[Sirrotica]

Originally Posted by TAKerry

Why would you do that? When im moving forward i put the car in D and go. P when i park. I have a buddy that was a truck driver. He has a unique way of driving an auto trans. Puts it in low everytime he starts and shifts through the gears. I thought he was going to kill the thing but he swears he has always drove that way with on ill effects.

And the answer is, I also drove big trucks for 7 years, 2005-2012. I drove super 10 to begin with, and regular 10, then some automatics. Shifting gets to be second nature when driving big trucks, you don't even think about it. Once moving in any stick shift vehicle, I never use the clutch anymore to shift gears.

Coasting increases the MPG in the 05 GTO 4L60E that I can actually see because it has a fuel usage average monitor. Back when gasoline was between $3.50- $4.00 a gallon I could get about an extra 1/2 mile per gallon from shifting into neutral when either slowing down for traffic signals or descending hills. Now I just do it from habit. Commuting 60 miles per day to and from the job saved a little bit of fuel, and every little bit helped defray the cost of 300 miles a week commuting.

I usually don't move the lever into low when starting out in anything unless I downshifted to slow down. I do sometimes move the shifter into a lower gear to slow down, depends upon the situation and what I'm driving.

The K3500, 4L80E below 45 MPH will disengage because it is designed to free wheel to save fuel, so downshift it for engine braking is kind of useless, and shifting to neutral is already covered by the transmission design of disengaging below 45 MPH. I know for a fact it saves fuel, because it shows up on the monitor in the GTO, and GM engineers made it as part of the engineering in the 4L80E in the K3500.

Anything with low final drive, 3.46 in the GTO, and 4.10 in the dually, let the idle speed drop back to roughly 600 RPM when coasting from 1500-2000 RPM if left in gear. It doesn't do nearly as much engine speed drop in the 99 GP because the final drive ratio is 2.86, I rarely shift the GP in to neutral unless I'm descending a longer grade straightaway. If it's a steep grade with switchbacks I'll downshift it to slow for the turns.

Driving a big truck as a profession, definitely will change your driving habits. I was in my 50s when I changed to driving truck, my driving habits and awareness to my surroundings have changed immensely. Because I drove fuel tanker the last 5 years the company's emphasis was always safety, and I attended many driver improvement schools during that time. With 8000 gallons of gasoline going down the road, you tend to be thinking ahead at all times, because the end result from an accident, you usually don't walk away from.

Professional drivers are usually safe drivers, but as with any profession you get the A holes that stand out to others on the road. The A holes are the ones that people remember too, they're also the ones that cause accidents, and ruin all professional drivers reputations.

[73LeMans]

Keep in mind, coasting is not legal in all states.

[Sirrotica]

Originally Posted by 73LeMans

Keep in mind, coasting is not legal in all states.

I'm from PA originally, and it has always been illegal in that state. I never checked into OH but it's probably illegal here too, but how would a cop ever prove it in court? Funny thing is it's legal to tow a disabled car in PA with a chain, providing there isn't more than 15 feet between the cars, and you pretty well know that the second car is coasting with no ability to stop from the lead car, other that rear ending it to stop.

Consider many late model cars with automatics go into free wheeling mode when you foot is off the gas and the vehicles speed exceeds the engine speed to save fuel. The old add on overdrives also had the same feature that they would free wheel if the engine returned to idle and the vehicle speed increased beyond the engine speed. It would be almost impossible for a cop to prove unless the engine was shut off while coasting. I do believe that that was the original intent of the archaic laws, not coasting while the engine was still running.

I'm not worried about violating that law because I never shut the engine off, be stupid to do that with almost every vehicle on the roads has power assist brakes and steering, not a good place to put yourself into shutting the engine off.

I'll ask, has anyone reading this ever been ticketed for coasting or have they known a instance of anyone that's been ticketed with the engine running? Post it up so we can all become educated.

[73LeMans]

Be pretty hard to prove a lot of the stuff written into the laws now- a-days. The texting crap made it pretty evident the lawmakers have no clue what the enforcing officers actually go through. I just wanted to put it up there for the OP so they can be fully informed about any choices they make.

[Simple Man]

Originally Posted by Sirrotica

And the answer is, I also drove big trucks for 7 years, 2005-2012. I drove super 10 to begin with, and regular 10, then some automatics. Shifting gets to be second nature when driving big trucks, you don't even think about it. Once moving in any stick shift vehicle, I never use the clutch anymore to shift gears.

Coasting increases the MPG in the 05 GTO 4L60E that I can actually see because it has a fuel usage average monitor. Back when gasoline was between $3.50- $4.00 a gallon I could get about an extra 1/2 mile per gallon from shifting into neutral when either slowing down for traffic signals or descending hills. Now I just do it from habit. Commuting 60 miles per day to and from the job saved a little bit of fuel, and every little bit helped defray the cost of 300 miles a week commuting.

I usually don't move the lever into low when starting out in anything unless I downshifted to slow down. I do sometimes move the shifter into a lower gear to slow down, depends upon the situation and what I'm driving.

The K3500, 4L80E below 45 MPH will disengage because it is designed to free wheel to save fuel, so downshift it for engine braking is kind of useless, and shifting to neutral is already covered by the transmission design of disengaging below 45 MPH. I know for a fact it saves fuel, because it shows up on the monitor in the GTO, and GM engineers made it as part of the engineering in the 4L80E in the K3500.

Anything with low final drive, 3.46 in the GTO, and 4.10 in the dually, let the idle speed drop back to roughly 600 RPM when coasting from 1500-2000 RPM if left in gear. It doesn't do nearly as much engine speed drop in the 99 GP because the final drive ratio is 2.86, I rarely shift the GP in to neutral unless I'm descending a longer grade straightaway. If it's a steep grade with switchbacks I'll downshift it to slow for the turns.

Driving a big truck as a profession, definitely will change your driving habits. I was in my 50s when I changed to driving truck, my driving habits and awareness to my surroundings have changed immensely. Because I drove fuel tanker the last 5 years the company's emphasis was always safety, and I attended many driver improvement schools during that time. With 8000 gallons of gasoline going down the road, you tend to be thinking ahead at all times, because the end result from an accident, you usually don't walk away from.

Professional drivers are usually safe drivers, but as with any profession you get the A holes that stand out to others on the road. The A holes are the ones that people remember too, they're also the ones that cause accidents, and ruin all professional drivers reputations.

Popular Mechanics disagrees.
https://www.popularmechanics.com/car...-fuel-economy/

[SRR]

"Bottom line: Don't coast in neutral. It's dangerous and won't save fuel. Turning off the key at traffic lights might."

That's just ignorant. I know some cars are designed to do this but I would much rather not wear my starter out sooner and be able to move my car not to mention keeping the AC/Heat going while I'm stopped.

[Sirrotica]

Originally Posted by Simple Man

Popular Mechanics disagrees.
https://www.popularmechanics.com/car...-fuel-economy/

I'll take real world information over 15 years, and 140,000 miles. I lose roughly 1/2 MPG with the fuel mileage monitor, and fuel average figured when I fill the tank up, if I don't coast, and gain 1/2 MPG when I do. That's for 15 years now, on the same car. When you can go further between fillups, you're gaining fuel mileage, it's hard to dispute that fact. I really don't give a damn what Popular Mechanics prints.

Hypermilers say the exact opposite, and claim that they can gain up to 30% better fuel mileage, just by changing driving tactics. That includes coasting with the engine running, with an automatic transmission..................

http://www.cleanmpg.com/community/in...threads/15044/

Ain't the internet great? You can almost always find two opposing opinions if you want to. Who do you choose to believe now...............

Was it necessary to even contradict me when your link can be nullified with a quick search on the net?......

Didn't some famous celebrity die today that you can post links to? I guess not because you have to follow me around PY just to try to cast doubt on a fact I know to be true. I have real experience, you on the other hand link to someone else's opinion, because you saw it in print on the internet. Popular Mechanics could never be wrong, so it's the gospel..................LMAO

Have a nice day......

[Jack Gifford]

Coasting certainly was popular in the late thirties- almost all the carmakers offered a free-wheeling feature. I wonder if any were sold in the flatlands of Kansas, etc.?