How to flush an automatic transmission yourself.

Posted by 92GSXman, Sep 5, 2004
Automatic Tranny - 4G63 automatic tranny discussions. Sponsored by Import Performance Transmissions

  1. 92GSXman

    92GSXman Proven Member

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    Wilson, North_Carolina
    I read somewhere that you could take the return line off of the transmission cooler and run the car in neutral while adding new fluid. Is this safe? Do you drop the pan and change the filter first? How many quarts of fluid do I need to flush the transmission? Any help will be greatly appreciated.
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  2. bus

    bus Proven Member

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    Alma, Arkansas
    You can take it to some shops (Precision Tune around here) and they will do it for under 50 bucks. Everybody that I know that has done it said it was well worth it. Never hurts in checking it out.
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  3. SlowSpyder

    SlowSpyder Proven Member

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    Los Angeles, California
    Exactly what you said 92gsxman. Do not drain the oil yet. First take the return line off the tranny and put that into a drain pan. run the car for a minute or till no more atf comes out, Which ever one comes first. then drain the rest of the atf from the pan and replace filter/gasket. Might wanna flush the tranny cooler lines with some cleaner if the oil looks real nice and yummy. Start out with 3-4 quarts, then warm up the car and keep adding till full
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  4. 1fast97gsx

    1fast97gsx Proven Member

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    Orland Park, Illinois
    we do this at my work actually. We drop the pan FIRST an change the filter. Put the pan back up. Then we take 1 of the trans lines going to the radiator or trans cooler and pull it off. We then tap into it there and hook up one line going to the flush machine, then another line going from the machine back to the cooler or radiator. We fill the machine with 16 qts or so and start the car. You then leave it running until all 16 qts have flown through the system to flush it out. Check the fluid color and if it's good then disconnect the lines and hook them back up how they should go. Check the level and add more fluid from there if needed. If you literally just drain it and top it back off you are definitly helping the trans by putting clean fluid in, but all the other stuff still in the system will still be dirty and it won't entirely clean it up. It's always best to do the pan and filter and then flush it out for a while.... kinda like doing a coolant flush. You don't just drain it and top it off .. you leave it running and cycle water through the system to clean it out. Then refill.
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  5. BUCK

    BUCK Proven Member

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    Summerville, South_Carolina
    I prefer shops that Flush new Fluid the the OLD Filter - THEN drop the pan - Install new Fluid & Filter.
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  6. 92GSXman

    92GSXman Proven Member

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    Wilson, North_Carolina
    Thanks for the info guys but I'm looking for a way to do this myself. I don't have a machine to flush cleaners through my transmission. If I take the return line off and run the car in neutral, won't that completely empty my transmission of all of it's fluid? That doesn't sound good. Am I missing something?
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  7. 1fast97gsx

    1fast97gsx Proven Member

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    Orland Park, Illinois
    yes it will .. and I don't think you can fill it as fast as it will drain. I've always hear you NEED the machine.
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  8. Microracer

    Microracer Proven Member

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    Felton, Pennsylvania
    OK then, based on what I've read this should work...
    - Remove both ends off the cooler
    - place one end in a bucket (old fluid)
    - Place other end in FRESH ATF (20 quarts or so)
    - Start Car in neutral
    - Run until most fresh ATF has run through system or sooner if fluid
    appears clean (cherry red).
    - replace lines on cooler
    - top off with ATF and test drive.

    Can it be this easy? OR am I missing something? :thumb:
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  9. jasoncitrano

    jasoncitrano Proven Member

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    schaumburg, Illinois
    what i did was just pull the pan off and let the car sit for a long time im talkin mabye over ngiht, let all the crap drain out of there, i got a pretty damn good amount of of it doing it this way. after that i replaced the filter and gasket (pain in the ass) and put about 6 quarts in, unless you use the flushing machine theres really no way to get ALL the fluid out...after this though i did notice alot better shifting from my auto.
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