This is a really good topic. It should be a sticky.
I'll consolidate some of my old postings here for completeness...
To remove the notorious transmission filter gasket, I sharpened the end of an old toothbrush into a chisel shape. Plastic won't harm the soft aluminum valve body. With a hammer, I drove the tip between the gasket and the housing until the gasket was deformed enough to grab with needle-nose pliers and it came right out.
The following is my own method of removing old transmission fluid. It circulates the entire system the way it would under normal operation, and delivers fresh fluid to the pump, torque converter, cooler(s), lines, rotating parts (gears, shafts, clutches etc) and valve body. This method does a good job, but requires a lot of fluid. To be any more thorough, the torque converter would have to be drained, and the transmission would have to go through all the gears while in motion, several times etc.
Keep in mind that you will never get all the old stuff out, and you don't need to. I talked to several transmission mechanics who say that under normal circumstances, doing a pan and filter service at the manufacturer recommended interval is all that's needed, (48,000km IIRC) and I agree. Those fancy machines they hock at quick-lube places were meant to flush your wallet. Only do a full flush if the transmission has had heavy use, or was not serviced in a very long time.
Under normal driving conditions, the ATF fluid is very durable. It mainly functions as a hydraulic fluid to transmit power through the torque converter and pressure through the valve body which is the brain of the transmission that actuates all the shifting mechanisms. It also cools, lubricates, and transports debris to the filter. Unlike engine oil, It is not exposed to combustion contaminates. Doing a pan service will replenish the oil additives that the transmission needs.
Anyway, onto the flush. Start with the pan and filter out per Lifted's instructions.
- 8 feet of clear vinyl tubing - 3/4" to 7/8" outer diameter. 1/8" thick.
- 1 large funnel - Bottom opening roughly 3/4" OD.
- 6L Dexron III ATF for OEM system. More for additional coolers.
- Large tray underneath transmission to catch the draining ATF
1. Thread one end of the tube into the funnel and jam the other end into the filter gasket (which you have already installed). You can double flare the end of vinyl tube with a bit of heat to make it fit snugly. It gets slippery once oiled.
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2. Hang up the funnel with a bungee cord.
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3. Fill up the funnel all the way and let the fluid settle to prime the pump so it doesn't run dry.
4. Start the engine. The pump will begin to quickly suck the fluid from the funnel, and a torrent of ATF will gush out the bottom of the tranny and into your pan.
5. Keep pouring fresh fluid into the funnel; It will disappear as fast as you can pour. When that transmission starts to make a slurping sound, shut the engine off.
According to my calculations, 6L should push out all the old stuff and send some extra through. Some old fluid will remain hanging in the TC and other parts but dont be concerned.
Reassemble per Lifted's instructions. I topped it off with another 5L (5 quarts) of fluid.