Transmission flush question...

[yourleftnut1]

I own a 4.3L with 70k miles on it. Decided to do a transmission flush just using the internal pump. After doing the transmission thermostat bypass MOD using the tap method, I hooked up clear hoses to the cooler. Started truck and let the pump do its thing. I've only managed to get about a total 8 quarts out including the fluid left in the pan. From my researches, a simple drop pan should get around 6 quarts and a flush should get almost all of it out. Somewhere in the neighborhood of 12 quarts if I'm not mistaken.

I checked the fluid level before the flush at normal operating temperature and it was on the HOT side. Did I get a false reading and i've always been low on fluid? Trans does NOT have any leaks.  I filled her back up with 8 quarts of valvoline synthetic ATF (red jug) after replacing filter and seal. It's on HOT and runs fine after a week now..

Gonna do another flush and see if I get the same amound..

[yourleftnut1]

i've done this to other cars before and I have gotten almost close to the max capacity specified by the manufacturer. 

[CamGTP]

I just suck the fluid out the dipstick, then I'm never wrong with how much I take out and put back in.

[Black02Silverado]

You can't pump it all out at once. You watch what is going into the bucket and when it starts to spit air you shut it off and add more fluid. This keeps the system from being completely drained and possible damage to the pump.  Once you pull out 12qts doing it this way you should be good but it is a good thing to add 2 or more qts. That way you pretty much have exchanged all the fluid.