Idea for true transmissions flush, good idea?

[Laser411]

So, I want to change out my transmission fluid but I never liked the idea of changing it several times to get mostly fresh fluid.

So here's my idea, get 2 airtight 3+ gallon containers. One is gets connected to the return line of the transmission cooler, the other gets connected to the output of the trans pump. A hose is run between the two buckets as I assume the pump won't suck the fluid up without some positive pressure.

So how this works, as the transmission pumps the fluid out, it displaces the air in the container which forces the air into the other container causing a higher pressure in the container with the fresh fluid (return hose must be at the bottom of the container or else you just get air into the return line) forcing the fresh fluid into the return line.

Basically, you are bypassing the trans cooler with another container with air in it to prevent contaminated fluid going back into the transmission. Does this sound like a good, workable idea?

 

[SilverSH0]

I'm going to guess that the air will simply compress and not feed into the return line. The transmission cooler works because fluid is incompressible but when you add 3+ gallons of air into the system there's plenty to compress before building enough pressure to push the fluid up. I think you would have better luck hooking a pump up to the return line so you're pumping fluid into the return line or lifting that 3 gallon bucket as high into the air as possible and letting the fluid flow down.

 

[Laser411]

Will the return line have a negative pressure if disconnected from the trans cooler in general? I guess I could use my new mityvac to create a positive pressure on the return line... Are the cooler lines easy to get at?

 

[SilverSH0]

Will the return line have a negative pressure if disconnected from the trans cooler in general? I guess I could use my new mityvac to create a positive pressure on the return line... Are the cooler lines easy to get at?

I've never done it this way so I cannot speak on first hand knowledge. However, I have asked the same question before and the answer was no it won't suck up new fluid in the return line. I've toyed with the idea of hooking up my pump to the return line and seeing if it would work that way. No idea how easy they are to get at.

 

[Johnbigdog]

A flush machine does what you are asking,but there is no such thing as free energy. The flush machine usually has a pump to help the process. The pressure that the cooler line creates will likely not have eough pressure to put back in the transmission. You would have to pump it in.

The cooler circuit is a separate circuit that feeds back to the sump. You could in theory use the cooler line to dump fluid out and pump fluid in through the fill/dip stick. But to get the right ratio is a good guess.

You could bring it to a shop. Have them use the flush machine but make it VERY clear to not use any other chemicals and to flush out any old fluid from the machine. A little bit of Macon V is Lily not going to hurt the 6F55.