how to flush AT transmission?

[ed1380]

I've read a few threads and the general consensus is that it cannot (or should not) be done without a flush machine.

Would it damage the transmission to have the engine idling in N while dumping all the fluid out the tranny cooler? I was thinking of doing that and then adding the required 7qts.

The reason i want to flush is because I found 2 empty quart bottles of type F fluid in the newly bought car and the tranny isn't doing well in the 3-4 shift

 

[loco4G63]

Well buddy, I can tell you this. I am in Afghanistan right now and one of our tactical vehicles went down because of contaminated tranny fluid. ATF was put in place of 15/40. What we do is with the vehicle not running we remove the in-going and out-going lines to drain the fluid. In your case doing this as well as removing the cooler isn't a bad idea. Allow the fluid to drain out of your lines, cooler and your transmission as well. If you do this after she is at operating temperature even better but do not do this with the engine running. After all the fluid has been drained out to the best of your ability, put some fresh fluid in and operate the vehicle for about 15 mins allowing the new fluid to recirculate. After that I would drain it all out again and drop some fresh fluid once more. We don't have any tranny flushing equipment per say : ) but this is how we do it here in Afghanistan. Our truck has not come back yet so thats my advice buddy. Good Luck!

 

[BoredDSM]

Nope, do it the correct way and drain it then fill it, run it again shifting through gears, drain it then fill it. Usually takes about 3-4 times to get it clean but its extremley dangerous doing it while the engine is running. Over filling an automatic trans is asking for trouble and under filling is just as bad. No way by eye can you pour the fluid back in at the same rate it comes out.

 

[the_mork]

If you really need the flush then do it the right way. You wont be saving yourself money by the time you waste a few quarts of fluid.

Also while absolutely using the wrong ATF is bad just go ahead and drain it, clear the tranny cooler with compressed air, then fill it again with the right stuff. When you're all done add a bottle of Lube Guard Black and you'll be okay.

Now, what is wrong with your 3-4 shift? You probably have another problem.

 

[ed1380]

in the past couple of days it's started slipping in the 2-3 shift and getting worse. I'm doing the flush tomorrow