ronjenx

Can you describe the "poor man's flush"?

The RTV method is easy. Do the bead between the bolt holes, and around each hole. Make a small bead so it minimizes what gets squeezed in the the pan.
I've used RTV on all the pans I have installed without a single leak.
RTV will eliminate the possibility of distorting the pan's flange at the bolt holes.

mfrank84

Think I'm going with RTV since I've got it on hand already. Just curious how you added your drain? Looks like the surface has been built up, at least from the photo. I was going to find the spot where I wanted to put it and drill the hole. Then I was going to use the oil drain plug from my Jeep (I added a Fumoto drain valve) and match it up with a nut. Then stick the bolt out through the hole and tighten down the nut and weld it in place. Remove the bolt from inside the pan and screw in the bolt outside the pan and hopefully I'll be good to go.

The poor man's flush is a way to replace the tranny fluid using the transmission pump on the vehicle. I've used this method on several vehicles, most recently a Nissan Xterra and a Toyota Tundra with great results. Fortunately both had transmission pan drain plugs and that made it a whole lot easier.

First thing to do is do a drain and fill on your transmission pan (perfect timimg when changing a filter). Theory being that this new fluid will replace the old fluid in the transmission as it's pumped up and through the transmission. If you have an auxiliary cooler, it's really easy to do. Just disconnect the outflow hose from the cooler to the transmission. Add a piece of hose/tubing to the outflow fitting of the cooler and place the other end in a collection bucket, marked with graduated quart readings. Have your replacement fluid ready. Have someone turn your engine on and watch the fluid being pumped into your bucket. At two quarts, turn the engine off (pump stops too). Add two quarts through the dip stick hole and repeat as many cycles as necessary to replace all the fluid (depends on transmission capacity). If the fluid you're replacing is old and dark, you can actually see the change when your new fluid starts to get pumped out. You'll know you've gotten just about all of it out.

For me, since I didn't drop my pan, I pumped three quarts out initially, and replaced it. Then I started the above cycling (five additional cycles) to get the rest of the old out. I bought twelve quarts of Walmart +4 ATF for $54. Considering the slight mixing of the old and new at the beginning in the pan, I probably replaced 95% of the old fluid. That's good enough for me. Once everything was set up, it took about thirty minutes to get it done. It really is easy.

ronjenx

The drain should go in the center of the low spot in the center of the pan. It's were the factory plug would be if the manufacturer had not gotten greedy.

Mine isn't built up. It's a bung and plug from a parts store. I picked out the lowest profile combination I could find.
Next to the plug is welded a tab I made to make it possible to safety wire the plug.

spartan99

Great thread.

I just learned how to do a poor man's flush and how to keep from losing my drain plug.

Jiblet

I've seen that people do passive exchanges by cutting into a cooling line and letting the trans pump out one side while the other draws in fresh fluid. I always wonder what fraction of the total volume that removes since the trans isn't actively going through the gears, etc.
Does anyone know or care to hazard a guess?

With the partial drain and fill accompanied by some driving or at least shifting the trans through it's gears, you can approximate perfect mixing, as mentioned above, 6-8 iterations with mixing gets around 95% of the old fluid out. Diminishing returns after that.

If one drain removes 1/3, then (2/3)^n equals how much original fluid is left, where n is the number of drains. Assuming perfect mixing.

I can't recall the volumes of the 42RLE. Is it 9 quarts total fill volume with 4 in the pan? I've forgotten.

mfrank84

For anyone interested in the allen head cap screw mentioned earlier in this thread, the size is 8m x 1.25 x 16. They run around 74 cents apiece at Home Depot and two for $1.27 at Lowes..

Ronjenx, did you feel confident that the hex head allen wrench you used was sturdy enough to tighten/un-tighten the screws without the head snapping off? The only reason I asked was because I read some reviews on this type of allen wrench and people were complaining about the head snapping off and putting them in a bind. Now, they could be talking about the really small ones, no one said, and I could understand that as there's not much to them. The one needed (#6) for the cap screws I got seems to be sturdy enough. The last thing I want to do is snap the head off in the screw. You said you've used them the last four times you've worked on a transmission so I'm assuming they are alright. Just curious.