Changing Fluid in a Transmission

[Gary Mintz]

Hey Gents and Ladies

I have a question concerning Step 2, If doing a complete fluid replacement.

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Step 2. Disconnect the oil cooler line from the oil cooler. As you may not know which is the pressure side and which is the return side, have both directed so the stream of fluid will be directed toward a receptacle.

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First increase the length of the transmission lines with clear hose then once you figure out which is which, couldn't one place the return line in say a 2 1/2 Gal Jug of new fluid and the pressure side in a empty 5 gal bucket and allow the transmission to draw it in as opposed to.

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Step 3. With another person, be prepared to add ATF to the fill area as it is being pumped out of the oil cooler line.

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Or sense it is a closed system is it a one way thing. I suspect it is this way but figured it wouldn't hurt to ask.

Gary

 

[2002 Maxima SE]

I have heard of folks on the Maxima.org board doing the old out/newk in method through the cooler lines. This should work fine.

 

[johnd]

I used to change the fluid in my '62 Pontiac using this method. I pressurized the "new fluid" jug with 2 lb. of pressure. Putting it up 6-8' in the air would have probably acomplished the same purpose. I put as much fluid as the trans would hold in the full jug and go until it was empty and the other full.

 

[Gary Allan]

On number 2.

I think that you're gonna end up with a static new fluid jug and a full used fluid jug. The pump pickup in the trans is a gravity fed system. There is no "pump suction" so to speak anywhere else in the system. The exchange systems use the pressure of the outgoing fluid to push a piston that is pushing in the new fluid. Kinda like a syringe ..but the plunger is pushed by the exiting fluid (it's a very big syringe).

It would be nice if there was an outside tap to the suction side of the pump that you could hang a hose in ...and a plug on the pan to just drain away the returned fluid. Then you could just attach a suction hose to new fluid and drain the pan into a container. The cooling line deal is the best DYI alternative.