Deeply confusing transmission leak

I’m really stuck here. I have a 2008 Explorer 4.0 V6, and a couple of weeks ago, I had a shift solenoid/wire harness failure. I replaced the solenoids, filter, pan gasket, and wire harness, and added new ATF. It drove fine for about a day, then started shifting roughly. I checked the fluid levels, and it was really low. I’ve filled it back up two more times, but it always drains out, stopping about half a quart low.

What’s strange is there are no puddles on the ground, no ATF in the radiator, no smoke in the exhaust, no ATF in the vacuum tubes, and I can’t see any leaks anywhere. I don’t understand how it’s using about half a quart in less than 20 miles.

Any ideas? Right now, my best shot is at gremlins.

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Could it be air bubbles possibly? How are you measuring the trans fluid levels though?

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I’m filling the transmission, running it until it’s warm, and then pulling the T30 screw inside the drain plug. Every time, I have too much fluid at first, but after I pull the plug, it’s completely dry. I’ve lost about three quarts in total, which seems like a lot for just an air bubble.

Earlier, I checked the transfer case and it’s normal, so it’s not leaking through the input seal. When I first did the repair, I had the pan off for a couple of days, and I think it kept dripping during that time. Is it possible the oil is just getting pumped further into the transmission? All the info I can find is about the pan capacity, not the total system capacity.

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i do really hop that someone else will share their input. It’s possible that some fluid stays in the pan and doesn’t drain out. The fill procedure for the 5R55S can be tricky. Check out YouTube for ‘5R55S transmission fluid’ videos to see what I mean

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@Lyod Keep me posted because mine has a similar issue. I was just quoted to replace the whole unit, and it costs twice as much as the car

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My current theory is that during the three days I had the solenoid pack out, the entire transmission drained. The whole system holds around 12.5 quarts, so every time I fill it, the pan looks full. But as soon as the car starts shifting, the fluid gets pumped through the gears and the pan empties quickly.

the other night, I added a gallon of ATF, putting in about one quart at a time to fill the pan. I stopped in between to shift through the gears until the pan was empty again. I don’t think I added enough, but it’s running better on the highway, so it helped. If you’re going to try this, keep your pump connected and use vise grips to pinch the output hose to stop it from draining