I have 30k on my 05 2500 Ram with a Hemi, automatic transmission and I am going to change transmission filters. I would like to replace as much of the old tranny fluid as I can when I change the filter.

First I was thinking about replacing the tranny filter and fluid in the pan. Then I would take the oil cooler return line off at the transmission and then start the truck to pump the new fluid from the pan through the cooler and catch it at the transmission. While I am doing this I would have to be adding fluid at about the same rate as it is being pumped out.

I don't know if this would work or if this is the correct way of doing things any help is greatly appreciated. If this would work which line on the tranny is the return line from the oil cooler?

Thanks

Yes it will work just fine. You will probably need a helper though. One to sit in the truck, one to be under to watch the tranny fluid coming out and one to be pouring new fluid in. I cant remember which line is the return but when your under there with the wrenches it wont be hard to find out.

Know a mech that does that with a good clean 5 gal bucket, just fills it halfway with trans fluid, adds an extension peice of hose from the line pulling trans fluid in and adds fluid as it needs it till good clean fluid is comming out.