DIY transmission flush?
 

I would like to do my own transmission flush, if possible. When I flush P/S fluid, I remove the reservoir return line and route that to a drain pan. I crank the engine (disabled fuel pump) and turn the steering wheel at the same time. I have a friend fill the reservoir as the pan fills up. On a coolant flush, I follow a similar procedure. I am confident that I have virtually 100% new fluid.

Can a similar procedure be done with a transmission (04 f150 4.6L)? As I figure, I'd have to unhook the trans cooler return line and route it to a drain pan. Then, could I start the truck and cycle it through the gears while someone else dumps new fluid in the filler tube the same rate the unhooked line is filling the drain pan??

The transmission holds 14 quarts, so I would likely cycle the 14 quarts as described, change the filter, and probably cycle a few more quarts through it just to be sure.

Questions:
How fast will the fluid com out of an unhooked cooler return line(engine running)?
Can I fill it at the filler tube or would I have to fill/pump it through the spot I unhooked the return line?
How do the dealers do a flush?
Will I get all the old fluid out or will some of it (as in the torque converter) just recurculate and not get flushed.
Can the dealer do a better job?
Would the dealer have to reprogram or do a flash to my truck afterwords?

I want the best, most complete job possible. I am willing to do this myself if need be. Sorry this got so long!!


TIA -jim

There's a thread about this somewhere...
I worked at a shop, and didn't like tranny flushes.

It would be easier to just drain the pan, then turn the torque converter until you can see the drain hole and drain that, clean up the pan(take the small metal shavings out, most should be on a magnet), change the filter, and add the new fluid. You should be good to go.

I have seen the process you are proposing described elsewhere on the internet, so I think you're on the right track if you want to take the time to do it. If you search "transmission flush" or something like that, I'd bet you find the site(s) I have seen before with that process.

the machines that do the flushes are pretty simple.... just a hydraulic cylinder.... when you hook the outlet of the tranny to the bottom of a cylinder full of fluid, it will just force the fresh oil into the system.... i would imagine that it would be very simple to find a cylinder to use, and just find the right fittings. when i did one several years back using the actual change machine.... it was a rather slow process.... i think the cylinder held like 15 quarts, and it took several minutes to pump it, so i held my foot on the gas pedal to speed it up some. this is a very good way to do it..... if you use a non-differential hydrualic cylinder, then you will only add the exact amount that you take out.... this way you wont have to worry about the fluid level either.