Hey guys i have a 2000 f450 dump truck with 166,000 miles on it. I tow anywhere from 5,000 to 15,000 lbs every day with this truck and since i live in florida, you can imagine the transmission gets pretty hot in stop and go traffic, especially in the summer. I read a ton of good reviews on the dorman 6.0 upgrade tranny cooler , so i decided to install one on my truck. Before the swap i was hitting 212* after driving usually about 30 minutes in a urban area in fl. According to the lovely lady on my dp tuner , she would always remind me that my transmission temp was to high, Ha! For those of you who don't know, she sounds like siri on a iphone. At any rate I installed the cooler last night and drove her all day towing my dump trailer as usual. The load i was towing today was no where near a heavy load, maybe 8 - 9,000. With that said , my highest temp i reached today was just under 200*(195 or so). Granted i didn't hit 212* like i usually do but i also was towing a lighter load. I honestly thought i would be reaching temps around 170* or so with the new cooler in.
Can anyone shed some light on this ? Does this sound normal?
Just so im sure i ran the lines correctly, the route goes as follows:
There is a line that comes out of the front of the transmission, goes up to and in the radiator, then comes out of the radiator and goes into the passenger side of tranny cooler, then comes out of the driver side of cooler and routes all the way to the back side of the transmission.
If this is the correct route, then why am i getting such high temps?
Thanks for any input guys, if you have any questions , fire away!

 

That routing is correct. I don't see high temps here at all, even before installing the new cooler.

It is possible that the bypass is leaking. A rebuild kit for the bypass is somewhere around $25. Summit has one on their website. It's easier to install than the cooler was.

 

Im not sure what the bypass is?

 

I think trans is Ok up to 230 dg or less.

 

Thanks for your input Mark, Can you please let me know what bypass you are referring to, and also i was going by my temp gauge on my tuner. the gauge shows it going into red at about 212 - 215*. What would you consider high temps for a rebuilt 4r100?

 

Here's an older thread where Mark explained it pretty well


https://www.ford-trucks.com/forums/8...ut-advise.html

 

The cooler lines attach to the trans on the passenger's side of the trans. There is a tube between those lines that is called the bypass. It has a pressure controlled valve that will open if the cooler circuit gets restricted. The valve can relax and bypass the coolers at too low of a pressure.
I consider the yellow zone to be between 220°F and 250°F. Red is above 250°F.

 

Great, thanks for clearing that up Mark. Glad to know i havent been running her to hot. Is there a way to tell if that bypass tube has gone bad? Or is it best just to fix it as preventive maintenance?

 

Your slightly warm trans is something of a test. I imagine devising a real test would take more time than simply replacing the parts. Not much to it, aside from keeping trans fluid from making a mess.

 

The tranny fluid exiting the radiator will approximate the same temperature as the engine coolant. If the tranny fluid is above the coolant temp, it will cool down; if below coolant temp it will warm up. The purpose of that additional tranny cooler is to supplement the cooling happening in the radiator when the radiator cannot provide sufficient cooling. So in a warm climate, it would be impossible to have tranny temps below 200 degrees when towing, especially if the torque convertor is unlocked (a major source of heat). The pumping of the fluid creates a lot of heat similar to an air compressor making hot air. The convertor spinning in an unlocked condition creates heat.

 

To test if the bypass is "leaking" is fairly simple.

• Disconnect the cooler hose from the hard line on the RF frame rail. You want the REAR hardline connection. This is important. Must be the REAR trans line.
• Put the hose from the cooler(s) into a bucket or catch container. (If it's clean, you can re-use the fluid you capture).
• Put a scrap piece of hose on the hard line, and route into the catch container.
• Have someone else start the truck at idle. Just let it idle.
• Observe the hoses. There should be NO fluid coming out of the hardline (rear transmission side) hose. If there IS, the cooler bypass valve is leaking.
• Don't run it longer than it takes to observe the flow.
• Put the cooler hoses back to normal configuration, refill and check trans level.

It's not tough at all.

 

I understand what you're explaining, but you're overlooking a few things.
The in-radiator cooler is in the bottom tank. The "cold" side. The lower tank temp is probably 20-30degF cooler than the "engine temperature".


The oil-air trans cooler is after the radiator. The 6.0 cooler brought my temps down ~30degF from the little 7.3 cooler. So even at 200degF trans temp, the 6.0 cooler was capable of at least 30degF of Delta-T. So the cooler lowers the temp another 30degF from what it was when it left the lower tank cooler.


So by my rough math, I feel it IS possible to have trans temps in the 160-180 range even in hot weather, with the radiator cooler.


The radiator cooler was added to provide transmission cooling when airflow through the air-only cooler wasn't high enough to provide adequate cooling. Like in snow-plowing, or low road speed such as hill climbing or off road.


I think the OP has an open cooler bypass valve. The big cooler should have lowered his temps about 30 degF from what he is accustomed to seeing.

 

Not sure I agree with that, I live in a desert and I my TFT never went above 185 summer and 130 winter even with ECT temps at 200 plus. Then I installed a Derale thermostat now I see 195-205 summer and winter.

 

"Then I installed a Derale thermostat now I see 195-205 summer and winter."

Pretty much the same here. We can get 100* + in summer and as much as ~ 15-20 below in winter.

 

This is totally incorrect.

The transmission cooler in the radiator is on the cool side of the radiator, after it has already cooled the coolant. The temperature inside the radiator near the trans cooler (I've measured this, I'm not guessing) is anywhere from 20°F to 150°F cooler than the engine temperature. When the engine is at max load, such as climbing a grade when loaded to the max, you'll see the smaller difference. The trans is also working hard, so both are making a lot of heat.

The purpose of the transmission cooler inside the radiator is to be the main source of transmission cooling. I've measured the heat rejection from the radiator cooler and the aux cooler.