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Discussion Starter · #1 ·
Normally what I would do is unhook the suspect line, start the engine and see which line bleeds. But I can't do that because don't have a radiator, main problem there is the oil cooler lines have aluminum foil over them.
I searched, because I am very sure its been asked before but I can not find it.

On the factory 6.2L transmission cooler setup which line feeds and which one is the return?

My guess is the top one feeds and the lower one returns?
But I cant test it, grrr....

Here is the setup I want to use:
An oil thermostat controls oil flow between the transmission fluid heater (the OEM cooler) and an air/oil cooler.
The transmission heater will heat the trans when its below 0 here and on warm up then the air/oil cooler will do the rest.
I am also going to add a trans filter (reused 10mic hydraulic filter) so I need to know which line feeds and which one returns for there to be any hope for this rig to work right.
 

· Mad (Sean) Max
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I "think" that the top one is the return. I put a hole in the top line once and it seemed to be spurting in the direction of the engine

Not the definitive answer you were looking for, I know
 

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I would advise not to use any type filter in the cooler lines. Just looking for problems. Better to just change the OEM filter once every two years. Any filter you put in there will create a resriction. Ford used a filter on their superduty trucks that does not create resriction but is more or less a bypass type filter. Called a toliet paper filter in the trade. Basically it diverts a small amont of fluid thru a microscopic "toliet paper" filter. Even if it stops up the cooler and the transmission continues to function effortlessly.

Motorcraft FT157 - Automatic Transmission Filter Kit | O'Reilly Auto Parts
Only problem using this filter is that it takes four connections to make it work.
 

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Discussion Starter · #5 · (Edited)
Thanks its backwards from what I thought it would be and that is good because there has been a big ass U-Haul installed transmission cooler installed since I got my suburban, they pulled the top line of the transmission heater and ran it through the cooler before going to the transmission.
I figured they might have tapped the top line since it just happens to be the easiest to get to.

Yes I know what you mean. The hydraulic filter I am using has a built in bypass so if there is more than 10psid across the media it bypasses around the filter, mainly for very cold starts with a high flow hydraulic system.
This filter is rated for 25gmp and was used on a system with an 11gpm pump.
I think the trans cooler system only moves like 3gpm.

I had this filter hooked up from 2007 to 2008 and the only reason I took it out of service was because I changed the filter one day and got a bad filter and it leaked no matter how much I tightened it down.
I couldn't find any new filters so I removed it.
Since then I found a source of filters.
 

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Discussion Starter · #6 ·
Yes you guys were correct. The bottom one feeds.

On another note the only reason I figured this out was because I needed to know which oil cooler line is the supply and which one is the return. I put an oil can on each hose and cranked the engine. Motor oil came out the top engine oil cooler line and to my surprise transmission fluid came out the lower trans cooler line.
 

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granted im not sure how strong the pump is on the 700r4. but on my 04 lightning i have an external filter before my f250 trans cooler.
if i blow the tranny id rather be able to reuse my cooler vs buying a new one.

but not sure of pump flow. but when i had it pulled last time it seems like it can move some fluid.
 

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Discussion Starter · #8 ·
but not sure of pump flow.
Ok you talked me into it, I will test it when I get the truck most of the way back together. :D
 

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I would advise not to use any type filter in the cooler lines. Just looking for problems. Better to just change the OEM filter once every two years. Any filter you put in there will create a resriction. Ford used a filter on their superduty trucks that does not create resriction but is more or less a bypass type filter. Called a toliet paper filter in the trade. Basically it diverts a small amont of fluid thru a microscopic "toliet paper" filter. Even if it stops up the cooler and the transmission continues to function effortlessly.

Motorcraft FT157 - Automatic Transmission Filter Kit | O'Reilly Auto Parts
Only problem using this filter is that it takes four connections to make it work.

That is false, you want to put a filter BEFORE the cooler so if you do have internal damage, all that crap doesn't ruin your expensive cooler.

Raybesto's makes a nice magnetic unit or run a large oil filter type.
 

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Discussion Starter · #10 ·
Plus I figure the hot transmission fluid fresh out the side of the transmission would go through the filter easier compared to filtering after its been cooled off.
 

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Plus I figure the hot transmission fluid fresh out the side of the transmission would go through the filter easier compared to filtering after its been cooled off.

The filter won't even know if its hot or cold. Its better to project the oil going in so if you do have the trans let go, the cooler can be reused.
 

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Discussion Starter · #12 · (Edited)
I am reinstating my hydraulic filter used to filter transmission fluid.
Its been up under the suburban since 2006 I installed it and used it for about 2 years then disconnected it due to a faulty filter seal on a road trip when it developed a leak. I disconnected/bypassed the lines and left the filter in place. I have not touched it till now.



I think most people put the temperature sender in the transmission pan. Since I cant do that at the moment I was going to plumb the sender bulb into the inlet of the filter. The transmission fluid will come out of the transmission and go straight to the filter via a rubber oil line, there it will meet temp sender bulb first before going into the filter.

Will that give me a fairly accurate temperature reading?

I think this might be better than an "in the pan" sender since it gets ran through a pump, plus through part of the trans case it will have the chance to be slightly warmer than whats sitting in the pan.
 

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· Ex- 6BT Square Body Man
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I think most people put the temperature sender in the transmission pan. Since I cant do that at the moment I was going to plumb the sender bulb into the inlet of the filter. The transmission fluid will come out of the transmission and go straight to the filter via a rubber oil line, there it will meet temp sender bulb first before going into the filter.

Will that give me a fairly accurate temperature reading?

I think this might be better than an "in the pan" sender since it gets ran through a pump, plus through part of the trans case it will have the chance to be slightly warmer than whats sitting in the pan.
Factory sensor on the 47rh I am using for my swap is on the outlet line to the coolers. I think it's a good place because that is where the fluid would be the hottest.
 

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Factory sensor on the 47rh I am using for my swap is on the outlet line to the coolers. I think it's a good place because that is where the fluid would be the hottest.
I think the oil pan is a better indication of overall temperature but regardless, its still an ok place to get a temp reading.
 

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Discussion Starter · #15 ·
That sounds good so that is what I will do.
 

· Ex- 6BT Square Body Man
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I think the oil pan is a better indication of overall temperature but regardless, its still an ok place to get a temp reading.
Fluid in the pan is mixed with cooled fluid coming from the coolers, the line coming out is carrying oil from the torque converter where most of the heat is. 30-40 degree difference between pan temps and line temp, guess it would vary on the type if trans but gives a rough idea.

Ideal setup would be 2 one in the and one in the pan, the pan one would tell how good the coolers are working
 

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Discussion Starter · #17 ·
Oil in the pan is mixed with cooled fluid coming from the coolers, the line coming out is carrying oil from the torque converter where most of the heat is.
That is what I was thinking.
If the coolers are working good then the peak temperature should never get into the danger zone anywhere in the system.
 

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Fluid in the pan is mixed with cooled fluid coming from the coolers, the line coming out is carrying oil from the torque converter where most of the heat is. 30-40 degree difference between pan temps and line temp, guess it would vary on the type if trans but gives a rough idea.

Ideal setup would be 2 one in the and one in the pan, the pan one would tell how good the coolers are working
Exactly, or read the cooler outlet line otherwise your reading TC temp and not really the true trans temp.
 

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we run ours in the test port for testing line pressure (4l80e)
 

· Ex- 6BT Square Body Man
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Exactly, or read the cooler outlet line otherwise your reading TC temp and not really the true trans temp.
There are upsides to both locations, on the outlet line you would know if your torque converter is burning up.
 
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