aod slow down shift.

[BerniniCaCO3]

There are two reasons for this.

One is that in a toasted transmission, the gritty mush that is what remains of the clutches might be all that allows them to hold at all, and once rinsed out, your clutches and bands might slip terribly;
Two is that if there is a buildup of grit, cleaning this out could free chunks of clutch material, that then get caught in the very fine tolerances of the valve body, and other funny stuff happens.

Since you've kept up with your fluid changes, it sounds like, you probably don't have this severe buildup of clutch material. I'd go ahead and do a flush. By "just did one 20,000 miles ago," you mean 20,00 miles and 2 years?

That rule is for folks who never heard of a transmission flush, and now their car is 15 years and 150,000 miles old, and it's starting to have shifting problems, and only now they're considering a flush. At that point their transmission is probably cooked, and they're on borrowed time now matter what course of action. A flush could either buy a little time, or rob them of what time might be left before the transmission goes from problematic to completely unusable. The transmission was already destroyed either way and what is being discussed is bandaid measures. To say old transmissions "like" dirty fluid is a misnomer

[BerniniCaCO3]

People who tow, put on city miles, push a plow, etc., might get slightly burnt fluid every 15,000 miles.
Burnt fluid loses essential properties; I think lubricating is one of the first to go.
So, people who do those things get flushes every 15,000 miles and probably all is good for a long life.

People who go 1/3 of a mile to the highway, and then it's overdrive from here to 60 miles there, and another 1/3 mile to their office; they could go scores and scores of thousands of miles, if their fluid never gets hot enough to burn.

[84merc951]

yeah it was maybe 50k sense last flush. ill give her a shot or try running some lucas or another doctor in a can. thanks matt

[gadget73]

I'm a big disbeliever in magic in a bottle. Just use regular fluid, and don't flush it. Drop the pan and drain the converter. If you find any surprises in the pan, start saving your pennies.

[ford man]

I would do a fluid and filter pan drop to be on the safe side. You could put some magnets in the pan while you're at it too.

[BerniniCaCO3]

here's another forum and thread where a guy has a similar issue it sounds like:

http://www.clickclickracing.com/forums/showthread.php?10707-AOD-doing-some-really-wierd-things-need-some-direction

[86VickyLX]

Do all the fluid, not just half of it. Drain the converter!

[ford man]

A lot less risk to do a pan drop on a transmission with 200k then to replace all the fluid... But to each his own.

[BerniniCaCO3]

You can start by unhooking the top cooler line and connecting a hose to the radiator end, run it to a bucket, and turn the car on in Park or Neutral to bleed out the cooler lines and quite a bit North of the pump as well. That gets a lot of it; but there will still be a quart or two in the pan, and a certain amount more in the converter.

[gadget73]

no. no. never. no. Do not ever for any reason pump the thing dry unless you really want to destroy the transmission. The pan unbolts for a reason.

[BerniniCaCO3]

If you're not in any gear, there's nothing applied. What would be the problem?
That's what we do in the shop, and apparently have done so for years-- as the preferred method, even, because it gets more of the fluid than just dropping the pan.

[84merc951]

thanks for the replies. okay so drop the pan and do the filter, and drain the coverter also. what fluid do you guys recommend with a trans with so many miles. maybe a thicker oil or thinner or do what recommended by ford. haha i also did the cooler lines with an old mopar 904 tranny that was shot. we didnt want to drop the pan so we took both cooler lines off. put one in an empty bucket to catch the fluid and filled another with a half gallon of lucas and half of regular new fluid so it would suck up the new and get rid of the old. worked good too. ive never seen a fluid so varnished that it almost looked greenish or semi clear. thanks again matt

[sly]

If you're not in any gear, there's nothing applied. What would be the problem?
That's what we do in the shop, and apparently have done so for years-- as the preferred method, even, because it gets more of the fluid than just dropping the pan.

because the pump WILL die that way... or be damaged when no more fluid is flowing through it.

[BerniniCaCO3]

Oh, and another older post on your same issue.
Seems more common than I imagined!

http://www.clickclickracing.com/forums/showthread.php?10753-Stock-1985-AOD-Downshift-quot-Binding-quot-in-Overdrive&highlight=governor

Huh-- no one ever warned me about that. Like I said, the whole shop does this on a regular, and even preferred basis, as running the pump with a cooler line open gets more than dropping the pan and refilling.
I'll do some investigating