Opened Auto Trans Fill Plug to top off Trans, but tons of ATF came out... Question

[maxplanck736]

When I Opened my Automatic Transmission Fill Plug to top off the ATF, a lot of ATF came flowing out (The Fill Plug is the upper plug on the large sump). I had assumed that since I know my ATF level is low, the ATF level in the large sump would be below the level of the fill plug. (I lost some of the fluid when I accidentally disconnected the AFT lines where they connect to the ATF cooler.)

Can I refill my trans by simply pumping ATF into the large sump fill hole until it begins to overflow? Or do I need to remove the small sump, fill it up with ATF, reattach it to the trans, and THEN fill the large sump until it overflows from the fill hole?

I don't want to bother with changing the ATF filter yet because I want to have the transmission flushed using an ATF replacement machine in a shop (supposedly it will suck the gunk out of the trans and clean it really good, so hopefully I will avoid having the trans die from crud that's knocked free by the ATF and filter change). I just need to get the trans filled with ATF so I can drive this car to the shop.

[roberttran]

http://www.pelicanparts.com/bmw/techarticles/E36-Tranny_Fluid_Auto/E36-Tranny_Fluid_Auto.htm

This is a good article to read. The car must be on and warmed up while topping it off.

-Robert

[choffa]

If the engine was off, all of the fluid drained back to the sump. As said above & in the Pelican DIY (same as shop manual), the fluid must be checked at temperature, in neutral (after cycling through all gears), with the transmission pan level (elevated to gain access). No need to check level of small pan.

Read through the end of Pelican's write up & follow it to the letter. These transmissions are notoriously sensitive to proper level (and a pain in the a$$ to check unfortunately).

[jamin325i]

normally to topup auto tran. warm up car about 20minutes-driving it is best.
with car running you can remove fill plug without excessive fluid loss-if there is loss probably because it was previouly topped up while too cold and now fluid has expanded-not your problem though.
no need to remove small sump.
i do not know how far to your shop.
so, if you are convinced you are as much as a couple quarts low from your fluid loss you might go ahead and top it up running but cold, before driving it to check level at proper temperature.
pulling the large sump to change the filter at some point is good, when i did mine i never tore apart my old filter-it is enclosed. however, i had much gray mush-couple tablespoon fulls-clinging to the sump magnet. so i assume that the filter was clogged. this likely was my cars 1st. filter change.