AudiWorld Forums - Trans fluid question

Quote:

Originally Posted by RobertV (Post 25157432)

Finally getting around to do my trans fluid. I plan to do the fluid twice and the filter once as has been mentioned.
As has been posted: do the fluid/filter first, drive car to circulate the fluid that didn't drain and then do the fluid again.
Does it make any sense to change the fluid first, drive it to circulate the fluid and then change the fluid and filter?
Maybe I'm over thinking this?
TIA

I personally don't think it matters which order you do it in. But, the further short cut I have done is not drive it in between the drain cycles. Just leave it up, start it and let it circulate well. Call that 45-60 minutes. I shift it between D, R and N/P several times as it is warming up and running, I also give it a brief bit of gas with brakes held tight to load up torque converter, though no more than a few seconds each time. Remember that a tranny has its own oil pump internally. It is driven by the engine simply spinning; importantly it is not driven by wheels spinning like a manual trans design would be. The differentials are separate fluids, so spinning them doesn't matter either. By doing it that way, I save all the set up time of getting it lifted up, level, and so on. 45-60 min is probably itself generous, but I figure by then I have tranny thoroughly warmed up--it passes above the top of the temp setting range by then too.

In doing this, I prefer to start cold with pan pull, having let it all drain down--or no more than time it takes to get up on ramps that I use for it. You are also working near the exhaust and cats, so don't want that full running temp hot for the pan work. Then I pull pan, replace filter and close back up. "Close back up" sounds easy BTW, but the paper gasket Audi uses is really fiddling and hard to position correctly as you try to insert early bolts. A helper can be good--I don't have one so suffer solo or even use my contorted foot or knee to try to hold pan and get a bolt or two back in. Gasket invariably starts to get oily too no matter how well you let it drain.

I then go on to my two+ cycle fill. If you want to flush it a little more, on first fill, start by getting it filled with engine off. Then start it and immediately pump in everything you can. Forget the final level setting procedure on the first pass; basically as it warms to 40C it would overflow the fill hole (that is open for the level setting procedure, but now closed the way I do it). Having a bit more in right for cold start just improves dilution, and what overflows once started will be that mix of old and new. Can do the same on second pass too, but now open the fill port at 40C to get the final level correct. It will drain back out maybe half a liter or so if you pumped full with engine running and back to at least cool. Obviously in between either leave it overnight, or plan a couple hour break between the two fills for cool down.