Been a while since I posted here but here is my situation. I am getting extremely high tranny temps. I'm talking upwards of 240* and even 260* when I am driving up the hill towards my house. Even when I am driving around town I am getting 220* on the temp gauge. The fluid is full and fresh. Where should I start? I am thinking either stuck valve or blown cooler. If it is a valve where is it to swap it out? If it is a cooler, I know the recommended one is off the 6.0. A list of parts and instructions would be greatly appreciated. Thanks guys

 

What is the condition of the cooler itself? Are the fins clean?

 

Sounds like the cooler bypass is stuck closed ...

 

Second on the bypass stuck open. Of course the bypass may be open due to a plugged cooler and doing what it is supposed to do. That is WAY too hot. There is definitly something wrong. You should be able to check the cooler temperature when the truck is running, trans oil hot. If it is circulating through the cooler, it will be just as hot. Simple check.

 

You could check for plugged cooler or obstruction by disconnecting the fluid return line from the transmission and check return flow. About a quart per 15 seconds or so I think.

DND58

 

Whats the condition of the gauge itself? Try and find an IR thermometer and see what the pan says.

 

Ford Super Duty 4R100 Transmission - Four Wheeler Magazine

 

Thanks for the help guys. I will break out the Chiltons when I get home today and do a check on the cooler and the valve. If the bypass is stuck closed then what do I need to do? Order new one and replace it or service the old one? thanks again

 

Replace it. If you looked at my link read up on it!

 

Please excuse my ignorance and lack of knowledge in this matter. I read the article and it did not explain how to replace the line. It said how to add spacers or braze the banjo bolts. That is what I'm asking. Is the line easy to get to from underneath the truck? Or do I need to drop the tranny to remove the line, like the picture had? As far as the cooler is concerned I tried to check the lines yesterday and on my 99 7.3 I have what seems to be a secondary cooling system in front of the radiator and the tranny cooler is in-between these two. I coudnt get my hands down there to unhook the lines. Thanks for the help

 

Go to ford parts in your area.Yes the cooler bypass line is on the pass side of the trany.Easy to install just keep things clean.Lines are about 16in long might be an exhaust pipe in the way.Start here first with your over heat.

 

After you change the cooler lines out double check for oil output flow on the return side. You dont want restriction here.I have seen where this replacement has cured overheats. Except for the early 99 psd needing the air to air cooler plus the lines replaced.

 

Thanks for the help Chop. I will go by NAPA today and get the parts. Would it be a good idea to get the aluminum spacers to put on the banjo bolts to block the holes, that way the fluid always goes into the cooler? Or just not worry about it. Thanks again.

 

The spacers would be my last resort.

 

Also did you check to see if your trany gauge is reading correct?