some weird things i have seen............
water pump ffrom old eng... some years may have impellers reversed.
was fan removed from clutch...seen them installed backward.
lower radiator hose...does it collapse flatten out.
Sure radiator is flowing....cold spots? use IR thermometer.
exhaust restriction...
is temp gauge accurate use the IR therm.
coolng shrouds installed...

try this remove t'stat rad cap off observe coolant flow for direction quanity.....don't rev it

 

It may be true that when your engine goes over 210, it can kick the tranny out of OD in order to reduce the stress on the engine. You will also lose about half your power as well. This is just a by design safety feature of the PCM to prevent you from blowing your engine when it is overheated.

Have you ever checked the radiator to make sure it is not clogged inside? Maybe a good power flushing of the radiator may help?

 

I just swapped my radiator. At 203,000+ miles on the stocker original radiator, I did an autopsy on it. It was easy to cut it open especially around the plastic ends on both side. I was very surprised that other than very lite rust slime, there was zero particles 'clogging' the bottom. I fully expected 2 inches of dirt/junk/etc. Nada.

We cut apart the fin areas and took out a few 12" sections. Light could be seen when shining in from one end to the other looking long way through the fins.

Had I known this in advance, I would have left it in place I think. All in all, it was due a replacement based on age and mileage if nothing else. However, the clogging I fully expected was non-existent.

I will get photos of the e-fan setup posted after the Carlisle reveal this weekend. Working flawlessly!

IndyDurango

 

The PCM locks out the transmission out of OD at that temperature because it will rev the motor so that the clutch fan will pull in extensive air to cool it. Also limp mode will occur if the transmission is too hot. This is usually caused by the engine being overheated and the transmission oil flows next to the antifreeze in the radiator (in it's own sections) is heated to the same temperature. Now the oil takes a long time to cool (not like antifreeze/water) so this is why limp mode was incorporated into this.

There is another section in the PCM as well. If the A/C is on and the truck gets to 210-215 (too hot) the PCM shuts power off to the A/C compressor and this allows the condenser to cool down and get much needed cool air to the radiator. After the engine cools back down it will release it back to engage the system.

This brings up another point. If the transmission gets too hot from (towing or other) there are 2 problems that will/may occur. Now it COULD go into limp mode or shut OD off, but usually the heat takes out the transmission first.