Trying to do the fluid exchange trick in my '03 FX4 with 4r70W, where you tap into the line returning ATF from the cooler to the 4r70W, and then run the engine to pump out old ATF, meanwhile adding new, until all fluid replaced. Sounded great in theory, but I'm a Mechanical Idiot, and as soon as I got under my truck it started to look harder.

First, there is no damn room to get at the fittings on the side of the 4r70W-- exhaust heat shield right there:



The two lines travel forward from tranny to cooler, one clamped directly above the other, in same relationship as they came out of the 4r70W:



When they get to front, weird s**t goes on. One branch goes to radiator, one goes to ATF cooler. I've flipped views-- the front of truck is to the left, the fan shroud is above, and the lines are separating to go to their different destinations:



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This shot is looking straight down next to radiator on driver's side. The line from the transmission plugs into the radiator (I think that is it at the top) and then another line emerges from the radiator (you can barely see it way down below) and goes to the ATF cooler:



This shot shows all the lines. One from radiator to cooler (top left of photo), one from tranny to radiator (top right of photo, traveling below the other on its way up from the tranny), and one from cooler to tranny (bottom of photo, traveling above the other line back to the tranny).



My questions are:

1) Is the line in the bottom of the photo, traveling direct from cooler to tranny (clamped above the other line and entering tranny above it as well) the "ATF return line" that I tap into?

2) Why in Hell does ATF go to radiator, anyway? I am mystified by that

3) Since it looks like a royal PITA to access the fittings on the side of 4r70W, can't I just tap into the ATF return line by loosening the fitting on the cooler? (hidden behind the soft line in the photo towards bottom, but you can see the other fitting on the line between radiator and ATF cooler, above)

4) What is under that fitting on the cooler? A ferrule on the line end and some kind of receiver for it on the cooler? Any way I can get a line plugged into that cooler to guide the ATF to a big 'ol bucket sitting next to the front of my truck so I can measure and observe what I am pumping out? Or do I just put a tub under the cooler and let her rip?

5) If I want to put a Magnefine filter in the system, would it be Ok to do it in that chunk of soft line that makes the curve between the ATF cooler and the hard line that travels back to tranny? How do I do it? There's not enough room to just splice the filter into the soft line in that curve. I'd need to make some kind of extra loop of soft line? With what kind of hardware?

6) Is it possible to disengage those factory fittings from soft to hard line, or is the only way to tap into system to cut the soft line in the middle and then splice in some sort of hardware, the filter, and a loop of soft line?

7) At what point do I drop the drain pan and inspect and replace the tranmission filter, before I start pumping fluid?

Any help, advice would be much appreciated!

k9dr

 

2. warms atf when cold. also heat exchanger but not good enough to have no trans cooler.
3. yes
5. yes i would use a remote filter with a fl1a.
6. no have to use tubing cutter. hoses are crimped together.
7. never, no point it never clogs up. remote filter will keep the fluid clean. http://www.supermotors.net/registry/4970/17326

 

Thanks very much for response!

OK, mystery solved.

I gather I've got the return line figured out correctly.....

Whats a fl1a?

Another dumb question: What size are these hard/soft lines? 3/8"? I gather they are gauged by inside diameter, so I am wasting my time with my attempts to figure it out from outside diameter....Thanks for your patience-- just starting to learn how to work on trucks......

k9dr

 

To cool it. The transmission cooler is in the cool side of the radiator. The coolant there has already passed through the radiator so it is cooler than engine temperature. Contrary to public opinion, the radiator transmission cooler NEVER, NEVER, NEVER warms the ATF. It does NOT happen.

 

A FL-1A is an oil filter - the one used by most older Fords and very commonly used by aftermarket remote oil filter systems.

 

Here's what I have done on every vehicle (auto trans) that I have owned for 30 years....

At 20k miles, I change the filter (due to possible residual/initial wear particulates that may be floating inside) and either drain the torque converter (if so equipped with a plug) or disconnect the trans cooler line at the radiator, fill the pan with fresh fluid, my wife starts the engine and when 2-3 quarts drain into a bucket, she shuts it off, I refill the pan and repeat until the fluid is clear and in case of the f150, 14 quarts of fresh fluid is in.

I change only the fluid after that (unless I determine substances/contamination in the oil). The intervals vary depending on the type of trans, type of fluid and conditions, but in general, every 30k miles. Heat is a killer on automatic trans fluid and when we lived in the desert area, I changed the trans fluid at the end of summer every year.

In regards to filters, oem is fine, but I typically use Wix.

In regards to trans oil, both in sticks and autos I have always used Valvoline.

I have also never had a trans failure in any vehicle I own and typically keep my vehicles for 10+ years, with over 100k on the odometer.

 

Thanks for replies.

So my trans fluid cooler system in my '03 Fx4 with 4r70W actually has two heat exchangers/coolers in series? One integrated with the radiator on the driver's (cool?) side, and then another small cooler behind the front bumper, and then the cooled ATF goes back to trans? Wow. I am amazed at the stuff I don't know about my truck until I start looking.....

Sounds like I'm doing the right thing with the ATF exchange, pumping new after old until all old out, and best way to do it is by uncoupling the fitting on the cooler that connects to the line carrying ATF back to the trans. And I read something saying that in an older truck the remote filter should be after the cooler. But still trying to figure out how to splice a filter in there.

Any takers on the question of Magnefine magnetic filter versus a Fl-1a setup?

And can I get somebody to tell me what the inside diameter of the soft and hard lines is, and what kind/size of hose and barbs and clamps I buy to splice my filter into the system?

k9dr

 

Yes, that's how it works.