Shifting into neutral kills tranny! What?

thanks for finding that post Jester243 from Chris. That would make sense with the pump. Guess it's all down hill from here, in DRIVE, that is.

 

holding gears is not a good thing. I've had to get on it before to get up onto the freeway, I was going 65-70 and I was in 3rd I think, well once I got to the speed I wanted I eased off the gas. Normally this would tell the tranny to shift into the next gear dropping my rpm's down to about 2k. well it held in 3rd for a few mins and eventually changed. How would this be a good thing? I even lett off the gas and it still held 3rd..

 

Chris should be on later if you wanna ask him a more detailed question it was just the first response I could find from him on it. Good luck

I am still curious to hear about this 9 mile thing your dealer came up with. That is the first time I have heard that.

 

When coasting, keeping it in drive helps your gas mileage. Putting it in N hurts it.

Specially with manuals, the forward motion of the vehicle is transferred to your engine and actually turns your engine. In a manual, coasting in gear causes your gas supply to actually shut off, until your engine reaches a certain RPM (usually ~800-1000). Im not sure how well a torque converter works in this case, but if my memory serves me correctly, at least the 1st gen truck have a lock up clutch.

However, at least for manuals, this can introduce a lot of stress. As the stress is opposite from the force applied by driving, the two forces acting in opposite direction of each other can slowly wear the metal down, creating stress cracks, etc... over a long period of time (kind of like taking a metal bar and bending it back and forth. Eventually it will snap, as opposed to just bending in one direction.

 

If my gas pedal ever sticks, I think my biggest problem would be coming to terms with the fact that I was wrong about that entire scenario being a gigantic overblown hoax, and then I'd probably take the opportunity to try some movie stunts (or SPY HUNTER!)

 

To get technical there is only a mechanical linkage when in overdrive on the 2nd gen 5 speed autos. In the other four speeds it's connected with a torque converter which works with fluid to transfer the power so there is no mechanical linkage.

as far as the pump not working in neutral here is why

The Pump
Automatic transmissions have a neat pump, called a gear pump. The pump is usually located in the cover of the transmission. It draws fluid from a sump in the bottom of the transmission and feeds it to the hydraulic system. It also feeds the transmission cooler and the torque converter.



Gear pump from an automatic transmission


The inner gear of the pump hooks up to the housing of the torque converter, so it spins at the same speed as the engine. The outer gear is turned by the inner gear, and as the gears rotate, fluid is drawn up from the sump on one side of the crescent and forced out into the hydraulic system on the other side.

from http://auto.howstuffworks.com/automatic-transmission12.htm

 

I think what the service writer was trying to pull out of the left side of his ass is that the transmission learned my driving habits w/ N. And a reboot would have trans relearn habits. Not sure about the 9 miles (right side, I guess) other then I'm guessing if it's being towed flat, around the 9 mile area the tranny starts to over heat or something.

 

Now, torque converter in my experience with aircraft engines means, that no matter how fast/slow the engine is going, the TC spins at a constant speed, other wise known as a CSD (Constant Speed Drive). Maybe this is why it didn't make sense to me as much. So I was basically thinking that no matter how fast the engine is moving the TC would make the pump spin at normal op speed.

 

The fluid pump (front pump) in an automatic transmission is run by the outer housing of the torque convertor (the slotted part going into the transmission) which is directly bolted to the engine via a flywheel or flexwheel assembly.
As long as the engine is running, & the front pump isn't damaged or hasn't lost it's prime, fluid is supplied at a specified pressure to the transmission.
If the pump has lost its prime (via a faulty 'check valve'), then while parked for a period of time at certain angles the torque convertor may drain it's fluid back into the transmission thru the pump creating a condition in which the vehicle will not move at all..

Service Advisors are salespeople, not mechanics.. they tell you what they think will make them look smarter then you to either get you to go away, or buy the job they're selling..

Hope this helps you out..

 

Yeah, in hind sight I wasn't thinking when I posted that.

What if you drive 8½ miles? Does the truck round up?

 

shoulda' got a manual if you wanted to shift gears.

 

...And the winner IS!

(that means, rep for you)

I especially like the part about the "Service Advisors". Greatness.

 

So are you saying as long as the engine is running it's ok to put it in neutral when coasting because the outer housing is still spinning?

 

The next Taco will be a manual, however Atlanta traffic sucks ass.

 

Man you tell the truth KENNESAWTACO. Speak it with passion.

 

now couldn't all this be avoided if toyota put a transmission temp gauge in the truck

 

I always thought the fuel shuts off when coasting. The engine/trans does all the breaking as oposed to the brakes when coasting, so wouldn't you be doing more wear to the brakes then just letting the truck coast?

 

The pump in every modern automatic transmission I have seen has been immediately after the torque converter--it is driven from the input shaft. If the engine is running, the pump is pumping, no matter what gear is selected or not selected.

Neutral might dump pump pressure to some internal components, but I have not looked through a hydraulic function diagram for this transmission to see.

Personally, I think the dealership guy was pulling that "9 mile void warranty" line right out of his ass.

 

What he said. If the engine is running then the pump is running. The impeller inside the torque converter is what transfers power to the internals of the trans. Fluid sheer inside the converter is where most of heat is created so if your not in gear and the impeller doesn't have to turn anything, then the heat load should actually go down.

I'm not positive what Toyota does about the rest of the trans but I know that they still send fluid to the cooler in neutral. They might just dump the fluid back in the pan and starve the rest of the components. That might be the reason for the warning.

As for towing, if the drive shaft is turning then other components in the trans are also spinning and creating heat. Since the pump is not running 'cause the engine is off, the fluid overheats and burns up the trans. If you see a RWD vehicle on a front wheel dolly it either a) is a manual b) has the driveshaft out c) is being towed by a moron who needs a new trans.

 

As the 2 posters above said. Engine running in neutral means the pump is pumping. And it's pointless to coast in neutral, and a waste of gas. As for casuing progamming issues, only a tech could clear that up.