I own a 91 940t. I've embarked on the challange of "virtually" flushing the tranny. I understand that the tranny hold 7.5 liters. What I've done is drain whats in the pan. I've done this four times now, and with great sucess. The fluid a bright red and is clean. My only concern is now it seems that shifting from first to second is weird now. It feels like the shift is very very crisp not so much harsh but just sharp. All the other gears are super smooth and fine. Is this normal shifting for the aw71??

I would agree that the full flush is simple. I consider it so easy, it's almost amazing that everyone doesn't do it. It's even SAFER than draining the pan in my opinion, because the threads on the drain plug are so easily stripped.

What you have described is what I consider to be normal post-flush behavior. You can notice a very defined 1-2 shift when the fluid is very clean. I just posted that in another thread, much to the same effect. There is no need for alarm. The only cause for alarm is, in fact, either a delayed (or nonexistent) shift between gears, or a slipping condition which would be equally problematic. The harsh/crisp shift is a characteristic of the Aisin Warner 70 and 71 transmissions. Some transmissions are smoother, and some are not. There are degrees of crisp shifting, and each transmission seems to have something of a personality.

The problem is likely not in the fluid choice (as Mr. Ringlee said; Dexron III only which is what you used... right?) but more because you have become acclimated to the comparatively sluggish shifting of dirty fluid. The amount of debris that travels through the transmission during operation is nothing short of astonishing. I ran the drain fluid through a coffee filter and ended up with a whole filter coated with junk, that had come from the transmission cooler. Much of it is thrown out of the trans during a fluid flush. The rest is usually too big to come out of the pan, and is better left alone. Dropping the pan is virtually unnecessary, but flushing the transmission is a great idea. How can you beat that kind of preventative maintenance, for only $25 for a whole case of trans fluid?
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1992 940 wagon, 72k
make people envious; smile often.

Chris do you use synythetic? Where do you disconnect the fluid lines? Do you use cheap fluid and flush several times? -Eric 93 945T 120K hollow cat.

Personally I don't use synthetic, although that's likely to change in the near future. The last car of mine that I flushed, I ran a case through the system. I use whatever decent brand that I can get off the shelf. Wholesalers don't offer decent fluid prices because they deliver, so I just buy at wherever is having the sale.

If the fluid is dirty (a customer of mine comes to mind) it might take as many as 20+ quarts before you see clean fluid. If so, keep pouring.

If I were going to change to synthetic, personally I'd spend the extra fourteen dollars on a case of dino Dexron III, and flush it out first with that, then drive for a few hundred with the dino oil in it to circulate the clean fluid and get any residual junk out of the system. Because I've had a bunch of thread problems with AW70 and AW71 drain plugs, I've been shying away from them. Often they're frozen or they've been crossed by some moron at a previous change.

Last time I did my own car, I used Formula Shell, because it appears to be the same product bottled under the Havoline name, but costs 30-40 cents less a quart. Plus I did the power steering system which is another thing I do when I do trans flushes. Usually I buy a couple cases at a time, or more.

I don't use a flush kit, rather I use a piece of fuel hose of the proper diameter to fit tightly over the top nipple on the radiator, where the trans line attaches. I put a measured bottle right in the engine compartment and watch it fill as I run the engine. I've never leaked a drop doing transmissions, I sometimes avoid draining the pan. I like to have a new gasket for the drain plug as well, for the times that I have drained it.


--
1992 940 wagon, 72k
make people envious; smile often.

I use Mobil 1 Synthetic ATF, I disconnect the top (return) cooler line, and I flush only once after first draining and refilling the pan with fresh fluid. After you run about nine quarts through, all of a sudden the fluid starts coming out bright red.

What fluid did you use? Dexron III is what is called for. Also, it is far more effective to flush through the cooler lines than to continually dump the pan. See the FAQ for instructions: real simple.

It was indeed dex III and I also used the drian plug. I thought about using the cooling lines to flush but I don't know how to keep fluid in the tranny faster than it runs out. Can you buy it by the gallon???

It does not pump out faster than you can pour it in. Use a long transmission funnel with a large mouth and pour the fluid in by the quart at the same rate as it pumps out, as noted on a marked milk jug. If needed, just shut off the engine to catch up. See the FAQ.