Making A Transmission Exchanger

Hello, My car has no transmission dip stick so I am currently looking at ways to change the fluid (I wont pay 350 to have it changed) I researched a transmission fluid exchanger but they are 5000 bucks. Neither are good options.

I am basically looking for a way to measure the amount of hydrolic fluid coming from one side and ensure that I am pushing the same amount (new fluid) on the other side. Does anyone know how to meter this kind of thing?

Thanks in advance

If you pump new fluid in at the same time as pumping old fluid out will you not be mixing clean fluid with dirty?
I think I would pump ALL the old out, measure the volume and pump that amount of new fluid back in.

you would think but it doesnt quite work like that.

you usually disconnect the transmission cooler which has a line coming from the trans (dirty fluid) and pump the new fluid into the input. Think of it like a big circle where you break part of the circle and replace what you take out.

Interesting problem. You might first have to find a flow sensor that is safe for hydraulic fluid.

I presume this is in the vehicle so weighing isn't an option?

This may be instructive: U.S. patent 9322306B2

If you use the new fluid to push the old fluid out then the amount that comes out must exactly match the amount that goes in - a bit like how a domestic hot water cylinder works. Just catch the old fluid in a measuring vessel and stop when the required volume is reached.

...R

Robin2: If you use the new fluid to push the old fluid out then the amount that comes out must exactly match the amount that goes in - a bit like how a domestic hot water cylinder works. Just catch the old fluid in a measuring vessel and stop when the required volume is reached.

...R

The trick is that the transmission itself has a pump so I would be measuring that pressure (the dirty fluid hose) and then matching that same pressure with a different pump (new fluid).

Basically I am looking to measure the amount of fluid from the dirty hose and then pump the same amount into the inlet using the new fluid. Surely this cant cost $5000 to make

Does anyone have any suggestions on actual pumps to do this?

EverydayDiesel: The trick is that the transmission itself has a pump so I would be measuring that pressure (the dirty fluid hose) and then matching that same pressure with a different pump (new fluid).

Basically I am looking to measure the amount of fluid from the dirty hose and then pump the same amount into the inlet using the new fluid. Surely this cant cost $5000 to make

Does anyone have any suggestions on actual pumps to do this?

That posting really has me confused. This seems to be a function you want to run while the transmission is under power and functioning. But the second part has you measuring the output volume and then putting in the same volume of new fluid.

which is it?

Paul

I think the point is that you can't fully drain a transmission as there are lots of cups and pockets the fluid is trapped in, so you have to spin it to get the old stuff out and shift any particulates. I suspect the exchanged amount is more than the capacity to get reasonable replacement percentage. Just guessing though...

EverydayDiesel: The trick is that the transmission itself has a pump

It sounds like you plan to open the circuit so that the transmission pump can discharge the fluid rather than push it around the circuit.

That leads me to wonder what happens at the inlet side of the opened circuit. Won't the pump just suck new fluid in through that in effect replacing the discharged fluid? (Assuming, of course that the inlet side is connected to a tank containing new fluid :) )

...R

"The trick is that the transmission itself has a pump so I would be measuring that pressure (the dirty fluid hose) and then matching that same pressure with a different pump (new fluid)."

There is NO pressure without a restriction to limit the flow. So, the restrictions would need to be identical in order for the pressures to be equal and then the flow is volume over a time measurement.

Paul

Hi, What vehicle doesn't have a Auto transmission dip stick.

When auto transmission fluid is changed, the transmission is usually given a full service, including filters and gasket and seal changes. When doing this you can ensure that all the fluid and gunk and contaminants are removed before adding the required volume quoted in the owners manual and service manual. (Including checking for metal filings indicating transmission wear) What can happen is the new fluid, due to its cleaning components, will loosen any chunks of gunk and that gunk will block up any fluid galleries causing more than 350 in repairs.

Usually the amount of old fluid is less than the required amount of new fluid.

Unlike an engine, auto-transmissions are not a change oil and filter, jobs done, type procedure.

Tom... :)

New Cadillacs do not have a transmission dip stick...

Ok I didnt want to get bogged down into this level of detail but here is how you change the transmission fluid in an automatic transmission.

  1. Suck the old oil out of the pan and store it in a container
  2. Drop the pan, change the filter(s) and reinstall the pan.
  3. Take the fluid from step one and put back in pan (will not affect filter because the fluid going in the dipstick is not filtered ;) )
  4. The transmission coolant lines are basically a big circle so I would need to interrupt the circle. (see picture below)
  5. The engine would then start which would activate the hydraulic pump in the transmission. This dirty fluid is then transferred through the system to the 'dirty' tank..
  6. I would need to match the psi with the pump that pumps the clean fluid. (why it is done this way I am not sure, it seems like you would be able to just use the suction but that is not the case with commercial transmission exchangers)

here is how they work if you are interested https://www.youtube.com/watch?v=yOXIGYLzef8 https://www.youtube.com/watch?v=Nia2dJPvN3U

|500x478

My original question is this... how do i 1. Measure psi/flow in one hose (only fluid / not air) 2. Match that psi/flow in another with a pump