Transmission cooler questions

What is the difference if I drain the transmission 1 or 2 quarts at a time by using the return line or draining 1 or 2 quarts from from the pan? What am I missing? Why doesnt that accomplish the same thing?

 

Much less mixing of the old fluid (from the return line) back into the system (because it goes into a bucket). To the point where you only need to do it once- not multiple times to cycle out an overall majority of the existing fluid.

Did you watch either of the videos that Timmy posted?

 

Thanks Andy, that makes sense and yes, I watched them and @Timmah!’s transmission fluid flush video too. Since the external cooler is installed that was the most relevant. Since I’m working by myself I think l’ll skip the flush and just do a drain and fill.

 

I really think that's the wrong move if your goal is to replace all the fluid. Get a 6 pack (for afterwards) and invite a friend over.

 

You're always taking a risk when changing atf on a truck you dont know.....
Scotty says the safest way is to take the old out and save it.....
If tranny is too old and its gone too far ......your screwed....
It that case you'd have to put the old back in.......recent video he had an Impala 400K w/orig factory atf......

Gasket on my pan was after market so figured mine had been serviced in past....
BUt I used the lucas tranny conditioner as a safety measure..

 

Truck only had 92K on it when I bought it 3-1/2 years ago and I just hit 95K in August. I wouldn’t even consider changing the ATF but it looked pretty nasty when I did the transmission cooler. That and the seller told me her late father used to tow a little camper to go hunting. It says “no replacement under normal use” on the transmission dipstick but I figure what he did wasn’t normal so here we are.

 

Did the flush like @Timmah! did in the video. Fluid started to look better at 7 quarts (4 from draining the pan + 3 by running and pumping out) and I figured I would leave well enough alone and stop there. Everything went well until I knocked over a container of the old ATF and dumped nearly two quarts on the floor. The cardboard I had under the truck in case I dribbled caught most of it but it still made a mess. Quick test drive to get everything up to temperature, fluid level looks right and it seems to shift smoother although I never thought hard shifts were a problem to begin with. I’ll just feel better knowing I have mostly new ATF.

 

I installed the Hayden 697 Transmission Cooler with hoses attached horizontally. In from radiator on bottom, and out to transmission on top. @Timmah! mentioned in his video to do it this way so that as the ATF enters the cooler it fills up from the bottom, displacing the air out of the top hose. If it was reversed the air bubbles would potentially get caught in the cooler. I also flushed the transmission oil using the @Timmah! method, added an inline magnetic filter, and replaced the filter in the transmission oil pan. Afterwords my MPG went up from 16.2 to 18.8!