I though I might do a write up since I haven't seen a how to with pics.
This procedure with allow you to flush all the fluid from the tranny, converter, lines, cooler, etc. I did drop the pan and change the filter and seal. If you don't wish to, then skip over those steps (
They'll be in yellow). The meat and potatoes of this procedure was taken from here
http://denalitrucks.com/forum/viewtopic.php?f=2&t=50. I added pictures and video (beware, they're big).
Let's begin with the supplies. We all know how frustrating it is to be in the middle of something and need a tool/part.
If you're changing the filter, get p/n 24208576. It's a kit that comes with the filter, gasket and seal.
Be safe and get 15 quarts of ATF. It may take less, but you want to be sure all the old fluid has been flushed out and you've got enough to top it off. I used Dexron VI ATF from GM.
You'll need to pick up a fitting for the radiator and some clear tubing.
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The fitting is a 3/8" inch brass trans cooler line fitting. I picked this one up at O'Rielly's. I did see where PepBoys had it as well. Just don't get the one that looks similar from Home Depot. It won't fit.
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The clear hose is just some 3/8" ID tubing from Home Depot on the plumbing isle. The tubing I got was ten foot in length.
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Next, you'll need a small hose clamp, flare nut wrench and something to catch the fluid in. As you can see, a 5/8" flare nut wrench fits perfectly...or you can use a cresent wrench like I did. I picked up a 5 gal bucket and lid from Home Depot. They were on sale for crazy cheap.
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Now, on to the procedure!
Locate and remove the upper transmission line from the radiator. It's located on the passenger side. If you have similar lines on the driver's side, then you have EOC provisions (good for you).
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To remove the fitting, pull back the black plastic bracket to prevent damaging it. It is protecting an E-clip (Do Not Remove). Now use a wrench to loosen the fitting. Have a shop towel handy. However, very little fluid will drip.
Once removed, put in your brass fitting. I used a little teflon tape for good measure. Next, attach one end of your clear tubing and use the hose clamp to secure it and to ensure no leaks.
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Then, route the tubing and tape it to the bucket to secure it. I did mine this way since I was by myself and needed to see the fluid while starting/stopping the engine.
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At this point, you're going to start flushing the system. Now I planned on changing the filter. So to help with the fluid in the tranny pan, you can go ahead and pump out the fluid down there. It will be much less messy. Be careful when you lower the pan, there will still be a little fluid left in there.
The sequence is as follows. Start the engine. Fluid will start pumping out the tube into the bucket. Watch the tube until you see bubbles or hear a bubbling sound and immediately shut the truck off. It will take about 30 seconds and will pump out 3-4 quarts of fluid. Add 3-4 quarts of new fluid in the trans dipstick tube to the full line on the dipstick and repeat.
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You'll do this a total of 3 times. You should see the fluid change color to a bright red/pink. Especially if it was dirty. This is when you know you've changed all the fluid.
Here's what mine looked like after the final flushing.
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Here's what the original fluid looked like. Kind of a dark purple.
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...and here's a video for Denaliano.
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At this point, I'll go over how to change the filter.
As I mentioned earlier, you'll want to pump out the first 3-4 quarts to make dropping the pan less messy. Once you've done that, you can begin loosening bolts on the pan.
Some folks use a pry bar to move the shift linkage out of the way to drop the pan, but I chose to remove the rear screw and loosen the front screw on the bracket so I wouldn't damage anything. Use a size 40 TORX bit on a 3/8 drive ratchet.
The shift linkage is located on the driver's side of the trans. The two Torx screws are on the top looking at it from the ground towards the rear of the trans. Those of us with a 4WD or AWD will need to remove the front D-shaft from the front axle to gain better access. It will rest on the exhaust Y-pipe. Some have done it without removing it, but I couldn't tell you how.
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Remove the pan bolts and snake the pan out. You'll see this. Obviously, be sure you've got a catch pan for any residual fluid.
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Now it's time to change the filter and filter seal. Pull straight down on the filter. You may have to twist it a little. Be careful because there will be some fluid in there. Once removed, look at the hole that the tube on the filter came from. You'll see the seal that matches the one in the kit. It's a huge PITA to get out. Some just inspect it and leave it alone if it looks good. I chose to replace it. Most folks use a hook tool to get it out. Mine didn't feel like cooperating. So I used a small flathead screwdriver and a light touch with a mallet. Once I got the edge away from the wall, I used needle nose pliers to get it out. Denaliano said anyone could borrow his reverse pliers to get this thing out (nice to know that now). He'll even pay for shipping.
In all seriousness though, be VERY careful not to damage the metal wall. It needs to seal tightly around the filter.
Here's what the filter seal looked like once I got it out.
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To place the new seal, coat it in trans fluid and use a socket of the same diameter on an extension (to give you something to hold onto) and tap it into place. The bottom of the seal should be flush with the bottom of the hole. Now, just seat the filter and be sure you've got it oriented correctly. It should look like this.
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Let's turn our attention to the pan. Here's a shot of mine after removal.
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Remove the old gasket and clean the pan and magnet. Use a couple of bolts to orient the new gasket and secure the pan back to the trans. Replace the remaining bolts and get them finger tight. Torque them to 97 in-lbs. Next, replace the rear Torx screw on the shift linkage bracket and tighten the front one.
Just clean up any spilled ATF (especially from the exhaust) and that's it for the pan/filter.
Back to the flush procedure.
Once you've completed the flush/fill cycles, just remove the hose, replace the fitting with the transmission line, fill the transmission to full cold line on the dipstick, start the truck and warm up the trans. When hot, check and fill to line on dipstick.
Congratulations! You've just changed ALL of you trans fluid. This is not a back-flush and will not dislodge any particles in the tranny. It is completely safe and easy to do. It may sound difficult, but once you get the fitting made, you can do a complete flush in less than an hour for only the cost of the fluid.
A big thanks goes out to Butch at dt.com for sharing the idea.
Enjoy.
