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Discussion Starter #1
New build, full manual valve body C6. Tranny likes to run 195 just running down the freeway with 85 degree temps outside. That is pan temps. Ive got a factory sized 2wd pan, 20K cooler in front of radiator and am bypassing the radiator. It seems to me that it should be running much lower than that when not being worked real hard. These are not flash temps or anything, just cruising.

trans builder wants a larger pan and a combo radiator/tranny set up. That doesnt jive with experience in 90's fords where we bypassed the rad to drop E4OD temps. Says an additional cooler wont help, but thats where Im leaning.

Anyone have any suggestions as I prepare for the wheeling season? Dont worry about the temps, or yeah, Id try and solve it somehow....
 

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Bypassing the radiator cooler is not a good idea. This same garbage is spewed around by alot of people who don't understand how things work.

They think because the engine cooling system typically runs at between 180-200 degrees, that it will heat up the tranny fluid and thus you will never get below whatever the thermostat is.

This is wrong, for 2 reasons.

Firstly, when the thermostat opens at (lets say 200 degrees), it allows coolant to enter the radiator via the radiator inlet, therefor coolant entering the radiator is about 200 degrees, makes sense right? Well when the coolant exits the radiator, the coolant temperature can possibly get down to around ambient... this also makes sense because a radiator is designed to cool.

Every single transmission cooler built into a radiator is in the outlet tank, after the radiator has cooled the coolant. Therefor, the transmission cooler is not being affected by the 200 degree inlet coolant, its being cooled by the near ambient coolant that's just about to exit the radiator.

Secondly, transmission fluid temperatures can rise to well over 350 degrees, EVEN IF the radiator could "only" cool to 200 degrees, its WAY below the potential 350 degrees. In reality, the 350 degree transmission fluid is being cooled by near ambient coolant. Water also cools far better than air, you would need a huge air cooler to offset the loss of cooling potential caused by not using your radiator cooler.


Hook your radiator transmission cooler back up and dont ever unhook it, laugh at anyone who tells you otherwise. External transmissions coolers are AUXILIARY coolers, they are not meant to replace the primary radiator cooler.
 

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Nailed it! Also, having the trans bolted to the engine that is running at 195, the transmission (being aluminum) will somewhat act as a heat sink.
 

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Bypassing the radiator cooler is not a good idea. This same garbage is spewed around by alot of people who don't understand how things work.

They think because the engine cooling system typically runs at between 180-200 degrees, that it will heat up the tranny fluid and thus you will never get below whatever the thermostat is.

This is wrong, for 2 reasons.

Firstly, when the thermostat opens at (lets say 200 degrees), it allows coolant to enter the radiator via the radiator inlet, therefor coolant entering the radiator is about 200 degrees, makes sense right? Well when the coolant exits the radiator, the coolant temperature can possibly get down to around ambient... this also makes sense because a radiator is designed to cool.

Every single transmission cooler built into a radiator is in the outlet tank, after the radiator has cooled the coolant. Therefor, the transmission cooler is not being affected by the 200 degree inlet coolant, its being cooled by the near ambient coolant that's just about to exit the radiator.

Secondly, transmission fluid temperatures can rise to well over 350 degrees, EVEN IF the radiator could "only" cool to 200 degrees, its WAY below the potential 350 degrees. In reality, the 350 degree transmission fluid is being cooled by near ambient coolant. Water also cools far better than air, you would need a huge air cooler to offset the loss of cooling potential caused by not using your radiator cooler.


Hook your radiator transmission cooler back up and dont ever unhook it, laugh at anyone who tells you otherwise. External transmissions coolers are AUXILIARY coolers, they are not meant to replace the primary radiator cooler.
This.

Every time I here about someone having problems keeping a trans cool I find out that their "trans guy" told them to bypass the radiator because "coolant hot". :shaking:
 

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Im running two coolers one in front of the radiator and the other one under my bed linked above. Solved my problems. I'd go bigger pan. And I'd think you could build that same tranny cooler as above with junkyard parts after seeing mine. The cooler looks to be a similar size to some obs Chevy tranny coolers with a fan bolted on it.
 

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add a 2 gallon reservoir tank inline with one of your cooler lines, better than reducing your ground clearance with a deeper pan imo, use a check ball if you have to mount the tank up high
 

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Discussion Starter #11
im borderline on engine temps already. If I can avoid a heat exchanger, I would like to.

Ill look into the reservoir tank idea.........

my understanding was tube and fin are not the best for tranny coolers, and stacked plates are better. I built a shroud and fan set up for my current 12x12 LPD tru cool cooler so I could mount it in the back, but it ran even hotter ther (moved to try and lower engine temps prior to installing a larger radiator, and no this radiator doesnt have tranny line options either).
 

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I ran two large stacked plate coolers in my bronco with a manual valvebody c-4 with a 3000 ish stall convertor, it would keep it down to 200ish most of the time.

I only had one cooler on it at first and it would run 220-240 most of the time, second cooler did help.

I have a manual in it now but that is coming out soon for a c-6 and I plan on a large stacked plate cooler with a fan and hope to add a cooler to the rad or use another water to oil cooler of some sort. An external filter may help add some volume as well but will cut flow if it gets plugged, not sure if it's really a good idea or just seems like it in my head.
 

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Then get the cooler above. It takes a huge cooler if alone.
I would not run the cooler above. He already has a much better stacked plate cooler with spal fan. A heat exchanger is a good idea, I have the CBR cooler shown above with a 40 plate plate cooler. I added the heat exchanger and it dropped temps but not a ton. You can find Orem heat exchangers from dodge diesels I think for a decent price.
 

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Bypassing the radiator cooler is not a good idea. This same garbage is spewed around by alot of people who don't understand how things work.

They think because the engine cooling system typically runs at between 180-200 degrees, that it will heat up the tranny fluid and thus you will never get below whatever the thermostat is.

This is wrong, for 2 reasons.
I'd add another reason to the mix. The operating temp of an automatic happens to be the same as the operating temp of an engine. So long as the cooling system is working right, it will maintain both at proper temp. The heat exchanger thats in the radiator works both ways. When the trans is cool, heat will transfer into the ATF and warm up the transmission and vise-versa when the trans is warm.

ATF begins to break down at about 250*F which happens to be the temp that engine oil begins to break down. Most modern vehicles have cooling systems that have sufficient capacity to keep both the engine and transmission cool with some extra capacity to spare (depending on GVWR)

Ed
 

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I run a similar remote mounted tranny cooler with fan in my Ranger. Warmed up 306, C6 with a 3000 stall PTC converter.
My trans temps will not get over 185* ever. Fan comes on at 175 and back off at 150. I wheel in warm southern summers without issue.
Before I swapped this cooler/fan combo I had a typical cooler in front of the radiator (Volvo fan) and the temps would easily spike over 220* under heavy load or when beating on it.
Pics of fan mounted and pic of rig for reference
 

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I say remote/auxiliary cooler because of the location of the heat.

Yeah, lets put all the really hot stuff in the same damn spot.
 
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