Transmission cooling lines, inlet vs outlet

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scoti

Royal Smart Person
Sep 5, 2019
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And in heat exchanger land, counter flow heat exchangers are more efficient. So I would think setting up the car would be the same idea.
I specifically asked my 2 'go-to' engineering buddies what their thoughts were for an automotive app after making my post. They agreed the system would still function regardless of how it's plumbed. They both also agreed that for optimum heat exchange, flooding from the bottom & discharge from the top is best.

Same @ the transmission. You need to ID the in/Out ports so they're flooding the pump. Aeration/cavitation is a pump killer.
 
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84cutspreme

Royal Smart Person
Jun 4, 2009
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I asked a very similar question to both radiator companies and transmission companies when I put 700r4 in place of 200c because I understood the in/out at trans swapped. Everyone told me it shouldn't matter whether it goes to top or bottom at the radiator and or aux cooler, it will cool either way. I still don’t agree with this because why else would an in/out be indicated for transmissions?
 
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84 W40

G-Body Guru
Dec 9, 2009
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Sure, the governor is on the driver side, but the round accumulator cap on the passenger side should look like yours too. The 200C and 200-4R, I believe, are the only "backwards" flow transmissions GM has with the pressure port on top and the return line on the bottom.

As far as the heat exchanger goes, it kinda doesn't make much difference which line goes where, although generally the return line comes out of the top line, although not always. The radiator is a cross-flow design on a G-body which means the coolant should be about the same temperature coming from the cross tubes entering into the tank whether top or bottom. But, since the coolant flow is down, it makes sense to run the transmission fluid upward against the coolant flow to maximize heat transfer between the two fluids.

As far as mounting an aux cooler, you would disconnect the return line to the transmission from the radiator. Connect one port of the aux cooler to the radiator port, and the other connection to the line going back to the transmission. You're effectively putting that aux cooler in series on the return line from the radiator to transmission. You're done. Theoretically, most aux coolers don't care which way fluid passes through them as it's a cross-flow air to fluid transfer anyway.

4l60e-cooler-line-flow-direction.gif
The picture that 69Hurstolds provided is the proper way of adding a cooler. Connecting the hot line to the bottom of the cooler will push any trapped air in the cooler to the top and the cooler will always be full and dissipate heat evenly.
Having the hot line connected to the top of the cooler does the opposite, acts like a water fall doesn't fill the cooler all the way and creates air pockets less cooling.
 
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G_RIDE_81

Apprentice
Oct 30, 2019
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Connecting the hot line to the bottom of the cooler will push any trapped air in the cooler to the top and the cooler will always be full and dissipate heat evenly.
Having the hot line connected to the top of the cooler does the opposite, acts like a water fall doesn't fill the cooler all the way and creates air pockets less cooling.
Interesting. Ok, I'll flood my aux cooler. Thanks.
 
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G_RIDE_81

Apprentice
Oct 30, 2019
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Everyone told me it shouldn't matter whether it goes to top or bottom at the radiator and or aux cooler, it will cool either way. I still don’t agree with this because why else would an in/out be indicated for transmissions?
I see the logic and how it shouldn't matter. I do believe, thought, that if the oil goes through the aux cooler right before returning to the trans it should be at its coolest temperature which is the whole point of the addition, ha ha!!
 
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