Transmission cooler layout/operation?
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Laughing Gas
Joined: Oct 2013
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Transmission cooler layout/operation?
Can anyone explain the transmission cooler layout in our trucks? Is it oil to air, or is it oil to water, using the engine coolant to cool down the transmission fluid? I searched and all I can find is threads about people using 6.0 coolers on 7.3s. No real info about the 6.0 transmission cooler in a 6.0 truck.
Frmr Ford Trans Engr
Joined: Aug 1999
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From: SE Florida
There is both an air to oil as water to oil cooler. First it goes through the cooler in the radiator where engine coolant lowers the temp, the to an air to oil where it is cooled again.
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Laughing Gas
Joined: Oct 2013
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I was confused because I thought it was oil to water due to where the connections are, but my Trans Temps stay 20F under the coolant temp when cruising on the highway towing 6000lb, which made me think oil to air.
Plus the 7.3 guys using these coolers meant it almost had to be oil to air.
So is the risk of mixing coolant and Trans fluid worth the cooling an oil to water cooler provides?
Laughing Gas
Joined: Mar 2012
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From: Portal, AZ
I have had many vehicles over the years with tranny oil to water cool never had an issue.
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Laughing Gas
Joined: Oct 2013
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It just seems odd that my trans Temps stay under the ECT when towing, if it's oil to water. Does it go thru the rad cooler and then thru the air cooler?
Maybe it was just a frontal area limitation for the cooling system group. I've heard they always seem to be fighting the designers who are responsible for aesthetics and aerodynamics.
Frmr Ford Trans Engr
Joined: Aug 1999
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From: SE Florida
The ATF never sees coolant at engine temperature. The cooler is on the cold side of the radiator. This side of the radiator can be as much as 100F colder than engine temperature. The coolant goes through the radiator to be cooled, right? The ATF is in the side that's already been cooled.
The radiator cooler is especially important when there is little airflow. This happens when backing a load. If you don't have a radiator cooler, the air to oil cooler is be unable to keep the trans cool in this condition.
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Laughing Gas
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Wow, 100f. That would make all of this make sense. I just didnt think it would be that much. Your explanation about low airflow situations makes perfect sense. I'm used to construction equipment without a fan clutch... so 100% fan speed relative to engine rpm all the time.
I am involved in dyno testing of Cummins QSB 6.7 engine installations at work, and when we do a cooling system test, the bottom radiator tube is usually within 10 or 20f of the top tube. These are full power runs, ran until Temps stabilize. The log I'm looking at now was 32 minutes long at 100% load. The greatest difference between top and bottom tube temp was 19.9F. And we only use oil to air transmission coolers. I've noticed competitors machines that have oil to water coolers though, and they are much smaller than our oil to airs.
I am involved in dyno testing of Cummins QSB 6.7 engine installations at work, and when we do a cooling system test, the bottom radiator tube is usually within 10 or 20f of the top tube. These are full power runs, ran until Temps stabilize. The log I'm looking at now was 32 minutes long at 100% load. The greatest difference between top and bottom tube temp was 19.9F. And we only use oil to air transmission coolers. I've noticed competitors machines that have oil to water coolers though, and they are much smaller than our oil to airs.
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Frmr Ford Trans Engr
Joined: Aug 1999
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From: SE Florida
You'll see 15-20 degrees difference across the radiator on a stabilized full power run. It didn't sound like that's what you were talking about in your truck.
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Laughing Gas
Joined: Oct 2013
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Right, I was talking about highway driving with a trailer, and I guess it was unfair to compare that to a full power dyno run. I don't have any experience with partial load cooling tests.
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