High Trans Temp

The engineers decided that anything under 260*F was OK.

FYI.

ATF+4 is a full syn fluid and good for all Chrysler transmissions built after 1990 if I remember correctly. Will double check later, right now the $#&%$+@ pager is going off agian.

Don

ATF+4® is approved for use in older transmissions and is currently utilized in newer Chrysler®, Jeep® and Dodge® vehicles. The previous MOPAR ATF+3® formulation was discontinued in 2005 and ATF+4® is recommended for all transmissions filled with ATF+3®.   Only certified ATF+4® is recommended for service of Chrysler Group LLC vehicles. The use of automatic transmission fluids other than ATF+4®, including those claiming to be like ATF+4®, could result in lower levels of performance, jeopardize transmission life and void warranties.   

amxpress wrote:
A quality synthetic ATF helps, too.
It stands up better than Dino oil at high temperatures.

Some synthetics will damage the seals on older transmissions and this is not good advice. If the temperatures inside the transmission are that high it is better to address the problem directly.

ATF temp should run about 60 degrees about the ambient air temperature. If it is 100 degrees out the fluid should be in the 160-170 degree range. If it is 60 degrees and the fluid is at 170 degrees there is a problem. It may be low ATF level or it may be a problem with the lines to the cooler or too small a cooler (if vehicle was not bought with the "tow package"). One relatively inexpensive fix is to have the pan replaced with a larger capacity one. That give the transmission roughly double the fluid and double the heat reservoir when going up a steep grade.

Worst case for the trans cooler is when the transmission is working hard as the vehicle is towing a load up a grade and you are going at a lower MPH so there is less airflow over the cooling fins (even worse at high elevations). Tow Haul mode is designed to minimize torque converter slipping and keep the transmission running cooler. If you have this use it.

If you do have the ATF temp showing above 220 degrees it is not going to damage the fluid which is good for temps over 300 degrees. Nonetheless I would pull over and let the trans cool down and check the fluid level unless it was nearing the top of a long grade in which case the downgrade will be very effective in cooling the fluid. My trucks fluid never gets above 178 degrees even last month when I was at high elevation with air temps as high as 113 degrees but I still kept an eye on it being a little paranoid when it comes to things automotive.

With my 2011 truck I set the trans in Auto and turn on Tow Haul and the smarts of the vehicle work impressively well - far better than any other tow vehicle I have driven in the past 40 years.

On my 2500 Dodge Diesel, when in 3rd gear with the torque converter not locked up the temperature rises to 200-205 degrees. If the TC is locked it never gets over 180 degrees.

This is towing a 10,000# trailer

I wasn't aware that the "tow" mode kept the TC locked in lower gears......Good to know!

You already have good quality synthetic fluid from the factory and as was said before, 230 is not a problem at all for it in a modern trans.
At 260~265 the trans will drop out of OD automatically to help prevent damage and cool the fluid better.

230 is no big deal for a few minutes. I've had mine to 250 before for short durations. I would do nothing but service the trans yearly.

Check to see if the trans. cooler needs cleaning.
I put TranSynd tranny fluid in mine - synthetic fluid. It can handle higher temps. The fluid is for an Allison transmission,

Look for a synthetic ATF+4 fluid - recommended by Dodge.

You will find it in many brands - here is one:
TRANSMAX ATF+4®
CASTROL TRANSMAX ATF+4® AUTOMATIC TRANSMISSION FLUID IS CERTIFIED FOR USE IN CHRYSLER VEHICLES.
Full Synthetic formula exceeds ATF+3® requirements

#1
Make sure that your TC is locking. Being a 2005, with T/H enabled you will get TC lock in 3rd and 4th, and if you manually select 2nd gear it will lock the TC faster than 25mph (if you are going slow enough to be in 2nd, manually select 2nd with the shifter to get it to lock). If the TC is not locking it will throw a code if being commanded to lock.

#2
Check the thermostat on the transmission cooler. They are prone to plugging up and getting stuck in the bypass position so only some/no fluid is being passed through the cooler. Mine is doing this now and I see 195* with no load running down the highway.

Here is a link on what to do. CumminsForum 48RE Overheating Issue

The stock trans cooling system on our Dodges works pretty good; it has to with the super sloppy torque convertor and marginal valve body :R
Remember that on a stock valve body, no fluid is circulated when in Park. If/when idling the truck, place it in Neutral to help cool it!

A quality synthetic ATF helps, too.
It stands up better than Dino oil at high temperatures.

If You have a problem at slower speeds get a big cooler with electric fan. This will help when not enough air is flowing thru the grill. You can also overheat a Trans quickly backing into an uphill site or a long backup situation. No air is flowing thru the grill and trans TC is unlocked. Having a Gauge will help you decide if any changes are needed over what you have in place.