kudos to "greasyfingers" on thedieselstop forum for posting.

has anyone tried this DIY transmission fluid exchange

http://www.google.com/url?sa=t&rct=j...92vC6EK109XFvw

 

Nice write up but not sure I want to go to all the trouble of trying to build this rig for changing out my fluid. Plus, I have very limited welding experience especially on propane tanks.

 

It's a homemade heated flush machine. Cool!

 

It is a really good idea!!
Although I would use a new vessel of some kind not one that is contaminated. I wouldn't run LPG residue through my tranny.

 

I did see one thing I disagree with in his procedure. He says to start the truck and let it run until both the engine and trans gauges are in the middle. This will only guarantee that the trans is above 50F, nowhere near warm enough to do this procedure even with a heated machine. The truck needs to be driven, and possibly with the trans cooler covered with cardboard to get the trans warmed up.

 

My local dealer charges $170 for a Torqshift transmission flush. I'm not sure it's worth the trouble of building the device.

 

If you can't build something like that for less than $170 you lose your google rights. Propane tank is $30 brand new if you can't handle a used one. Heater element is $20. Surely the other crap can be put together for less than $120. Even if you had to pay a guy to weld it that shouldn't cost much. Honestly I probably have 90% of that crap laying around the shop.

Of course the real savings comes when you do it more than once. And the fact that I won't take my truck to the dealer for anything out of principle alone...

 

Or drain, drop the pan, clean off magnet, re install pan, refill. Drive 10 miles drain again and refill. $75 of fluid. Of course this will work for a standard service change interval not a trans with a grossly over due fluid change or heavy contamination. Still $170 isnt all that bad...IF you can find a dealer with the heated flusher.

 

If you do this, you've changed half the fluid if you are lucky. Take half of that used ATF that comes out and mix it with half a new quart. It will still be very dirty, and that's what's left in your trans. I see no reason to bother taking the pan off if that's all you are going to do, the magnet does not need to be cleaned regularly.

If you've kept your trans clean with regular drains/fills from the pan you probably don't need to worry about this. If you've let your fluid get dirty, or, bought a truck that is dirty, just draining the pan will take many many cycles to actually make the fluid clean.

 

I really like the concept, but I don't like the lack of precision for the fluid being pumped back in.

Would you be able to set up a sealed recovery tank that you plumb the old fluid into. Connect a vent line to the top of the tank and run it to the top of the new fluid tank. As old fluid is pumped into the tank from the transmission the displaced air would flow through the line to the new fluid tank and build pressure. That pressure would force new fluid back through the return line and back into the transmission. If there were no leaks the exact amount of fluid that was pumped out of the transmission would be pumped back in, assuming of course the temperatures of the fluids were the same.

What do you guys think?

 

I think that's how the commercial machines work. I've wondered if you could modify a water pressure tank with a bladder inside like you would use for a well. Not sure if it could take the heat...

 

That is more or less what my post suggests.