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[guncharmer]

Hello,i have searched the forum and asked questions on threads but am none the wiser. When i change the atf in my auto box i would like to get all the old fluid out. i realise just dropping the sump wont empty the torque convertor and also realise if i change what comes out,run the engine/box and change again and again and again that eventually i will get to a nearly all new fluid change but the mathematics on that procedure means i will get through gallons of atf.
So the question is, are there pipes the main dealers or specialist garages connect to and pump all the old stuff out or is there some sort of other procedure to empty all of it?regards.

[sparkyw666.]

the only way i would think it to take the box off and tc out and drain it that way . Also you would need to drain the oil cooler as well.

[feeutfo]

you cant get it all out without magor surgery as said, you'll only be able to swap out about two thirds of the fluid by dropping both sumps.

[Bionic]

Everyone please read this.
I have the same problem inasmuch as I want to change the ATF completely due to its brown colour. I also put out quite a lot of questions to various other clubs and helplines but the only one that appears to be without risk and makes any sense is to either drop both sumps time and time again until the ATF looks near enough the right colour - ie reddish, or to drop the whole thing including the torque converter.
One suggestion I got was to disconnect the flexy pipe that goes to the oil cooler in the main radiator and to briefly run the engine until the fluid stops.
This sounds risky to me and although it would probably work I  am hesitant to do it in case it damages the gearbox. On the other hand and while driving I suppose it would be no different from sustaining a burst pipe to the cooler and it being pumped out while the car was in motion - you would not know about until it lost all its drive I suppose?
I have worked on coaches with auto boxes that had lost drive after they had lost all of their ATF do to a component failure (usually the torque converter rim seal going) and all that happened was that the failure was repaired, the box refilled and bled and it was as good as ever.
Who is right?
Anyone done it before?

[Kevin Wood]

Running the engine until the fluid stops will do exactly the same as dropping the sumps. The ATF in the torque converter will not drain unless you remove the torque converter. It's effectively a large round container on its' side and the only way for fluid to go in or out is through the centre!

A partial fluid change will drain 6 or 7 litres of fluid IME. That leaves another 2-3 litres or so. In my opinion, that's diluted the old fluid enough. Do that every 60K miles and the box will be a happy one.

I have seriously considered putting drain plugs in my gearbox sumps though.

Kevin

[unlucky mark mv6]

Can you get some kind of gearbox flushing agent like you do with the engine,as this may help a bit. :-/

[VXL V6]

I have seriously considered putting drain plugs in my gearbox sumps though.

Kevin

Had them fitted to mine. Simplifies the job no end.
However i'd still be tempted to drop the sumps every 100K (I change the fluid every 40K using the drain plugs) as well to clean the magnet and filter..... At least dropping the sumps with no fluid in them is less messy!

[Kevin Wood]

Can you get some kind of gearbox flushing agent like you do with the engine,as this may help a bit. :-/

Since the automatic gearbox contains a load of wet clutches the fluid and its interaction with the friction material is critical. I wouldn't put anything other than the specified ATF in it.

Kevin