I have 98 XJ, with a pretty fresh stroker, only like 7k on it now. The Jeep had 265k on it when I bought it blown up, and since it's been back on the road with the new engine, it seems to drive great. I've never had an automatic before this, so maybe I don't really know - but, it seems to shift smoothly enough. Only issue seems to be that when I'm in 1-2 I only get 1... But I'm not sure how that's supposed to operate really, not very concerned with that though. So, more or less, it drives well.
Considering, however, the totally mistreated and ignored maintenance state it was in when I got it, I am certain nobody has serviced the AW4 for probably over 100k. I would jump all over changing the filter and flushing out all of the old fluid, but after reading online some, it seems possible that whatever old fluid is in there, with all of the old clutch material suspended in it, is the only thing keeping it going. But that's no good, I don't want to go on running a ****** old used up AW4 into the ground, I want to prolong it's life as best I can, make it clean and happy, and not worry about just how close it is to the end.
So, I just wanted some opinions on where that puts me, what I should do...
Thanks.
Reports from the field tend to indicate that a "power flush" of the AW4 isn't a good thing (although I've never tried it.)
I'd say to buy a case or two of Dex II/IIE/III/V, a filter kit or two, and do this:
- Drop the sump, clean thoroughly. Do not dismount the valve body. Clean the magnet in the pan thoroughly. Replace magnet. Clean the crud out of the sump pan itself. Replace the filter. Wipe clean (
lint-free rag - if you don't have that, don't bother. "Lint-free wipes" for electronics are excellent for this) Clean mating rails. Install new gasket. Install pan (replace lost screws with M6-1.0x15 or M6-1.0x20.
DO NOT OVERTORQUE SUMP PAN SCREWS! I've not used RTV on the gasket, I've never needed to. You may if you like.) Fill with four quarts.
- Put 5,000 miles or so on the box, drain & refill (don't drop the pan, don't do anything with the filter.
- Repeat.
- Repeat.
(This should get most of the loose crud out gently.)
After another 5K, pour a pint bottle of Berryman's B-12 "Chemtool" into the transmission, drive it around for 2-3 days normally, drain, and refill. (This will start to get the crud that
isn't loose.) You may drop the sump & inspect the filter at this time (I'd suggest it, but it's not strictly necessary. If you want to monitor progress through this process, drain the fluid such that it will run over a coffee filter - it has enough "tooth" to it that it tends to catch a good sample of crud that flows over it.)
The reason for all the changes is simple - unlike with the engine, when you pull the sump plug on the transmission, you'll only drain about half of the fluid ("dry fill" on the AW4 is about eight quarts, most of which ends up staying in the torque converter. Drilling the case is typically required to empty it.)
The reason to do it gently is that most slushboxen will end up "adapting" to the crud they collect (until they don't work!) and you have to give them a chance to "adapt" to getting rid of it. If you blow it all right out at once, you'll end up screwing something else up (not deliberately, it just usually happens that way.)
NB: Like your engine, drain the transmission
hot. This ensures that the maximum amount of crud is still suspended in the fluid when you drain it.
As far as the only getting first gear in the 1-2 range, this is normal for the AW4 - the controller "forces" it into first as soon as it can do so. No, we don't know why. Going to a "manumatic" controller (there are a few available) will give you the option of driving it as an automatic or as a "clutchless manual" with full control of the four gear ranges. There are a few designs out there - we have one or two sponsors that have the things, and you can also find them on Toyota enthusiast's boards (the AW4 is a Toyota design, and was known as the "30-40" or "A340" series by them. It was used in Celica, Supra, Toyota pickup, and some RWD Lexus models. I believe there is a five-speed version extant, but I'm not sure about swapping the one for the other - the controllers are certainly different, and you would have to have the five-speed have a standalone controller or know the truth table for the solenoids to build a manual shifter for it. The five-speed variant is predominantly Lexus, but I think it's also in the Landcruiser and Highlander.)