Why do you think this? Besides wasting fuel, you give a truck thief an easy target. The high idle feature was designed for quicker warm up from cold and extended idle periods when someone is in the vehicle and needs to stay cold or warm, depending on the season.

 

No, it does NOT circulate the same in park as neutral. The 48RE DOES NOT circulate fluid in park unless the VB is modified. Feed to the TC and the cooler are both 0 psi. Extended idling in park will destroy the pump gears and the TC hub.

The quote from the manual references power flow NOT fluid flow. Check the FSM, it clearly defines fluid flow in all the gears and what components are used.



Here is what happns when you idle too long in park:

 

So the high idle is a gimmick by DC to blow our trans.???

 

Huh, lets see. I get going in the am and it is 15 degrees outside. I drive a ¼ mile to the barn to load up, takes about 10-20 minutes. Then I go ½ mile to drop off the items and see what’s going on, takes 10-20 minutes. Then I go back to the house to get more coffee and make a phone call, 5-10 minutes. Then off to work 30 minute drive and shut it off for the day.

My question was about idle in P or N.

 

I think it's pretty clear for the 48RE. Idle in Neutral (with the parking brake on). Or better yet, get a better flexplate, converter and tranny with a valve body that will circulate the fluid in Park (and take a lot more HP and TQ). Then everybody's happy.

Tony

 

Now why would they make us idle in park...and being in the arctic we idle quite a bit and have never seen the above happen.

 

LVTony is not the first person I have heard about this from. Had several rebuilders tell me the same thing about a Dodge, Do Not idle in Park or risk your trans to what happend in the photos above. BTW this is why they say to check your trans fluid in N as the pump don't work in Park! It's been this way on all Dodge trannys from the 727 all the way up to our RE48

JMHO

 

If you're in conditions that warrant High Idle then why would you be concerned about keeping the tranny cooled? If the truck isn't pulling anything and is sitting in cold weather I would think you want to put some heat IN the tranny?

 

Thats probably why we never hear of it...also I leave my truck pluged in after I start it (when its cold - 20 or lower)till I'm ready to go.

 

The problem is only partially with cooling. The other part is lubrication. Those are steel gears in a steel housing. The snout of the converter runs in a brass bushing. With the trans in park there is no circulation of fluid in or out, the pump and converter sit there and spin in the same fluid constantly and generate heat in less than a pint of fluid. What happens when you over heat ATF?

The cooling is needed for the pump and TC snout not for the rest of the transmission. Beside, on the 3rd gen trucks the fluid never gets to the cooler until the fluid temp reaches a certain point. It simply routes back into the pan at the junction on the side of the block.

Obviously there is going to be a lot less heat held in that area at -40 than there will be at +40 degrees. The environment is going to play a large part in how soon damage can occur so this probably doesn't happen as often in the northern climes as it would in AZ. Even if is cold enough to keep things from overheating you still run the risk of hot spots developing where the oil film is not as good due to the lack of pressure.

Bottom line is the stock setup is not good for extended idle at any time or temp.

 

Okay, based on the schematics in the service manual (the hydraulic schematic shows pressure to the TC in Neutral), I understand that there is no fluid pressure to the TC in Park, and the only lubrication and cooling fluid available is what's already in there - not much.

I will idle in Neutral... unfortunately, my high idle doesn't work in Neutral.

So I may as well just not take the time to idle in the mornings at all - just use the block heater and drive off.

 

Nice, were these from your truck?? I'll bet that made your day!!

 

My high idle works in Neutral on my 2006 and yours should too.

 

i think now DC wants you to leave it in neutral, and use the "stick & seat" trick on the brake pedal

it just worries me to pull in with a HEAVY load on it at a rest stop, and leave it in Neutral to circ fluid thru the tranny while i run in. hate to chunk it in park & let it set there at pulling temps, with no fluid circ'ing

FWIW, this gets posted up about once a month, but the diagrams & pics are the best data i have seen so far.

 

i have also been told they do not circulate fluid in park which i do believe to be the case. my tranny temps will go up 20 degrees almost instantly-from shifting from neutral to park-when idling!