4T80-E fluid capacity

[hjb981]

I am planning on changing my automatic transmission fluid (ATF) by dropping the pan, opening the drain plug that is in there to drain the side cover, replacing all possible filters and then refilling with fresh ATF. I am not sure how much ATF I should buy. I have the factory service manual (FSM), and as far as I can see, there are two volumes that could apply in my case: 7.5 or 10.4 L. This information is written in the FSM:

FSM, Book 1

0B-9 Maintenance and lubrication

Approximate fluid capacities

Transaxle pan and side cover: 7.5 L, 8 Qts

Transaxle (overhaul): 12 L, 12.6 Qts

FSM, Book 2

7-6 Automatic Transaxle 4T80-E

Fluid Capacity

Bottom pan removal (requires drain plug removal): 10.4 L, 11.0 Qts

Complete overhaul (with existing converter): 12.0 L, 12.6 Qts

Dry: 14.2 L, 15.0 Qts

What is the difference between "Transaxle pan and side cover" and "Bottom pan removal (requires drain plug removal)"? Does the first one imply that the side cover goes off, but the internal drain plug for the side cover is not opened, leaving some ATF in the bottom of the side cover?

Maybe someone has done an ATF change, and knows how much comes out (and subsequently needs to be replaced with new ATF). As a sidenote: is it possible to also drain the torque converter (after removing the bottom pan) in an easy way? Have I understood thing right that I can easily replace the two scavenger screens, but not some internal filter that is situated under the side cover, or can the filter under the side cover also be changed easily?

[KHE]

It is not possible to drain the torque converter without removing it from the vehicle.

Not sure but I seem to recall dropping the pan and removing the drain plug takes around 6-8 quarts. My practice is to put the old ATF into 1 gallon milk jugs so I can measure the exact quantity drained. I then fill the transmission with the same amount I drained out so I do not overfill it. After shifting through all the gear selector lever positions and pausing after each one per the shop manual, I road test the car to warm up the fluid. After that, I add additional fluid if required.

The scavenger screens are visible once the pan is removed. The side filter is not servicable unless the transmission is out of the vehicle for overhaul or other reason. Then the side filter is accessable.

Be sure to use the OEM (or equivalent with steel bushings) pan gasket - not some POS cork gasket. Cork gaskets WILL leak - it is not a matter of if but when... GM sells a kit that contains new scavenger screens, the pan gasket, and the o-rings that retain the scavenger screens. It used to be cheaper than just the pan gasket alone but that may have changed.

While the pan is off the transmission, after cleaning it, I use a Sharpie (marker) to number the bolt holes with the torque sequence. That makes it MUCH easier to follow the sequence when laying on a creeper under the car. After the pan is torqued, some laquer thinner on a reg will remove the marker numbers.

[hjb981]

Thanks for the tips, I will definitely pick up on the idea to number the bolt holes. And when it comes to filters and such, I prefer to stick with the OEM stuff, so I will get that kit. I just checked on rockauto, and the kit is 30 dollars, compared to 27 for only the scavenger screens (I could not find only the gasket sold by itself, but I need the whole kit anyways, and I doubt that I would find the gasket only for less than 3 dollars). My only question now is how much ATF to buy. From KHE´s answer, I guess that the line "Transaxle pan and side cover: 7.5 L, 8 Qts" is the one that applies if one does a normal "drop the pan and open the drain plug" fluid change. It would be nice to get some confirmation on this, though. I would rather be safe than sorry (buy 11 L of ATF if in doubt), but if I can know for sure that 8 L is enough, I definitely prefer not to buy 3 L that will just sit around and age.

Measuring how much goes out is a good idea. How did you collect the used ATF in milk jugs? Did you use a really large funnel, because I imagine that it will spill all over when I do it, since there is no other way of draining it than unscrewing the bottom pan (btw, I will be doing it in a place where any spill ends up in a tank and is properly taken care of).

Is there anything else I should think of, do, inspect etc when the pan is removed? I plan on cleaning out the bottom pan and magnet with break cleaner, is that a good procedure? How do I know if the bottom pan "looks good"? It is the first time I will be doing this myself...

[KHE]

I use a cat litter box to collect the fluid - it is larger than an oil drain pan and is rectangular in shape. The sides are 6 inches tall and it measures about 18x24 inches. Even at that, I place a tarp under the car to keep fluid off the garage floor in case any spills. Once the fluid is in the drain pan, I use a large funnel to transfer it to the jugs.

You could also disconnect the return line out of the radiator and connect a length of 3/8" brake line and let the engine pump out the fluid into a bucket. I haven't tried that method but others have and report that it works well.

After the bottom pan drains, wipe it out with a rag. Brake cleaner spray works well for the final cleaning. Clean the pan bolts and the threaded holes in the trans. with the brake cleaner as well. You will see silver-grey clutch material in the bottom of the pan - that is normal and not a cause for concern. If there are large metal shavings in the pan, that could be a cause for concern.

The o-rings that retain the scavenger screens can be difficult to remove because they get hard with age and heat. Lube the new o-rings with transmission fluid when inserting them.

[hjb981]

I also read about the radiator return line method, and I guess it is a pretty convenient method to change the fluid only, but of course if the pan is going down anyways because of the filter change and magnet cleaning, the benefit would not be as big. Actually, the scavenger pump is supposed to pump up as much as it can from the pan and store it in the side cover anyways, so maybe it would not make any difference at all on how much will be in the bottom pan when it is dropped. I had the fluid changed a few years ago by a shop (including new scavenger screens), so hopefully the o-rings will not be too stuck.