I fill the trans with a cheap 1 gallon Home Depot weed sprayer. I cut the spray nozzle off and used a heat gun to bend the tube into a u shape. Fill with 4 quarts, pump it up, and pull the trigger. Using those bottle pumps sucks some serious a**

 

To do a triple flush, I dropped the pan and cleaned it up. I found where the filter sits. It installs in the transmission case, but is also sandwiched in with the pan. Avoiding where the filter sits, and looking for space, I added a drain plug, as jimbob8915 shows in post #23.
The “bung” I used is McMaster-Carr #12555K81. There are probably available elsewhere, but I shop there a lot. I drilled the hole and prepped it, but had a welding dude do the weld.

Why do this? I wanted to drop the pan just this one time to add this drain plug and change the filter. This way it is easy to drain most of the fluid from the pan without having to take it off. On the A8 transmission, it is difficult to reach the back pan bolts and re-install/re-torque. You have to jack the transmission up some to get to those bolts. So, dropping the pan 3 or more times was not appealing to me. Plus, whenever I feel like it, I can do a "fluid only in the pan" change.


McMaster-Carr bung Drawing


Bung picture


Bung in pan / Outside



Bung in pan / Inside

I didn’t want to mess around with the fill plug and hole, so I made my own adapter to fill through the level-check hole. On my A8, that hole is 6mm x 1mm thread. I used McMaster-Carr #1859N185. This straight thread will not seal in the threads like tapered threads (such as NPT). So, I added an o-ring on it for a little seal. Just screwed in by hand. I wanted a shutoff valve and used a quick connector common in my work, so the whole thing got a little complicated, but the key is to adapt 6mm x 1mm to whatever connection you want.
Warning: Not all GM pans use the same 6mm thread. I did the same on my daughter’s Camaro, with a 6L50 transmission, the thread is 12mm x 1.75


Fill tool

You can also buy fill tools from other sources. Search the internet for “gm transmission fill adapter”. One example I found was CTA tools #7431. I wanted to make my own adapter, again for the added "extras" I put on it.
Just watch for the correct thread size!

To fill, I used a pump which screws into the Mobil fluid bottle. I used Sta-Lube #SL4344, from Napa, but there are many different brands. Just watch hose sizing and that the pump fits on the bottle thread size.
To go through that many drain/fill cycles, and bottles, is a workout.

In answer to jimbob8915, post #29: GM used to put drain plugs in some transmissions. Like my 2001 Tahoe. But, even in the “old days without bean counters” they didn’t always do so. If I bought a new car, I would gladly pay for the option.

In answer to Dreamer2, post #31: I feel the proper DIY triple flush is done by draining the pan and refilling a number of times. Bulletin # 18-NA-355 reads that way. During each fill, you run the transmission through Park/Reverse/Drive to get the new fluid into the body and torque converter. This exchanges the old hygroscopic fluid for the new improved fluid.

Dan

 

Welding a bung in a tin pan is well and good, but what if you have an aluminum pan?? Putting a bung with a nut on the back side, would this seal good? I have a oil extractor, pump it a few times and your done I use to extract the oil out of the jet skis. Just stick the tube in the fill hole and it sucks the fluid out. Holds about 2 gal.
This is just a thought for filling. What if you put a length of 1/2 plastic tube into the fill hole, ran the tube above the exhaust pipe out to the side of the car and up higher than the transmission, then stuck a funnel in the end and filled. I was thinking about this while trying to get to sleep last night. Didn't work.

 

Now I am curious. Are you saying there was no way to get the fluid into the transmission?

 

No, I did not say that. It's like sex, there are many different ways. Just some are easier than others.

 

Machine broke on the mechanic. He struggled to get done. Didn't know how exactly and forgot to ask.