AW4

Is this trans japanese? Is it durable, any issues or years to be careful of? Thanks

I will start by mentioning that when describing the AW4, the word "durable" is usually done in bold all caps.

I'm sure you will get replies from others but you can search with "aw4*" if you are in a hurry.

I have an almost new AW4 in my 91 Briarwood. I have wheeled this thing way harder than it should be. Ive gone where my bud with a (Cherokee XJ) 4" lift and 35's has gone and made! later down the trial a mixture of poor judgement and distraction got me stuck. Here is where the AW4 comes into play. I have the 242 transfer case (2wd, 4 part, 4 high, N , 4 low). I jammed the tranny in drive and reverse and floored it in all possible settings to no avail. After getting pulled out i thought my AW4 would be toast from the aggressive shifting and high-revving. It still runs smooth as when it was installed. I am new to jeeps but the AW4 has been great. Not a fan of the 4 speed auto. but it does well!!

Durable is an understatement.

They will usually tolerate being run dry on fluid at least once (to the point that the vehicle won't move anymore) without getting ruined.

Current history of the one in my DD:
Bought preinstalled in the jeep. Approx 200k miles. To the best of my knowledge, no maintenance performed.
Drove for a few months, then the head gasket blew between cyls 3 and 4, resulting in a very rough running engine.
Continued to drive, but with foot on floor because it wouldn't go fast enough otherwise. Transmission exposed to severe torsional vibrations for ~10-15k miles because of this.
Partway through that period, got it stuck in the woods when a stump hidden under some underbrush snagged my front crossmember. While facing downhill on a slick muddy hill. I was pissed off and late somewhere, so I stuck it in 4lo, then neutral dropped it from 5000rpm repeatedly into first, reverse, first, reverse, etc to walk myself off the stump. By the time I was unstuck the temperature gauge was well into the red zone and I could smell transmission fluid cooking.

Continued to drive it. Put a new engine in, continued to drive with a lead foot. Once the horrible sounding engine was no longer in the jeep I could hear other drivetrain sounds again and noted a strange rhythmic rasping noise from the bellhousing, but didn't care enough to do anything about it. After a year and a half or so the transmission started slamming into gear after hard braking and slipping badly into 2nd gear for the first few minutes while cold, I assumed it was on its last legs and started collecting parts for a 5 speed swap. Then realized it might be low on fluid... added a couple quarts and it went back to working fine again. That was in November or so, I've put another 10k miles on it since then.

I've heard tales of people bursting a line in the woods and filling the transmission with stream water instead of ATF to get themselves home... then draining it back out and running ATF again with no signs of damage.

It's a japanese transmission, made by aisin warner. They are also used behind the 2JZ-GTE in the Supra (supposedly people have made them survive up to 1000hp in those), the 22RE, 3VZE, and 5VZFE 4 and 6 cylinder engines in Toyota pickups, and I know for a fact it's the same transmission that's behind the 4.7L V8 in my uncle's Tundra.

Regardless of country of origin, the AW4 is right up there with the TF727, TH350 series, and maybe even the powerglide in terms of reliability. And they're common as dirt and just as cheap, too, so there's no real reason to go to anything else even if you manage to blow them up if you like autos, it's easier to keep putting damn near free bolt-in units in every few years than it is to change everything to upgrade to another type of transmission.

Anything else you need to know will probably be in this thread: http://www.naxja.org/forum/showthread.php?t=1053970

I've nuked two, but one was already lurching and slipping before I got my hands on it (I have no idea what they did to it) and the other required incredible abuse, including being run out of fluid at highway speed once and at lower speeds several other times, before it failed, and still gave a lot of advance warning that it wasn't happy with me before dying. The only reason I'm still collecting parts for a 5 speed swap is because I prefer a standard transmission if I have a choice.

Oh yeah, that transmission fluid I smelled cooking? It's still in there, I never bothered to change it. Also forgot to mention I've towed upwards of 3000lbs several times with that jeep in recent months, always in overdrive even though you're not supposed to. At this point I just kinda want to see what I have to do to this transmission before it'll actually die.

edit: oh yeah, it's in my daily driver and still sees full throttle redline every day... without any slipping, except when the cooler lines leak enough fluid out (again) that it starts slipping on shifts once in a while. Then I feed it another quart or so and it is happy again.

As a testament to how tough they are.

I have two in my garage I can't give away. Nobody wants them because they never fail.

Re: Re: AW4

DrMoab said:

As a testament to how tough they are.

I have two in my garage I can't give away. Nobody wants them because they never fail.

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Yah me too. Ran across a couple super cheap so I grabbed them up for spares....5 years later.. still have not needed them nor does anyone want them.

Mine has never been touched except for filter and fluid changes. When I got it the fluid was almost black and smelled terrible, so I took it to a friends transmission shop.

When he started draining the fluid it looked more like gear lube (well not quite) but really bad. When the filter was removed it had so much crap in it you wondered how fluid flowed through it, it was bad. My friend said it was one of the worst he had seen where the trans. had not been trashed, transfer case was very dirty also. The amazing thing was it shifted and worked just fine and he drove it also.

Upon inspection of the trans. & transfer case he sais just change filter and fluid and go. I did and now it seems to shift even better, oh yeah I forgot to say this was at 242,000 mi go figure, Sounds like this is not uncommon as is the 4.0 seeing at least 250,000 a lot and still going strong, mine still is.

I think ken takes the award for most abused aw4.
All I can say is mine works great at 223,00 miles and the previous owner not taking care of it. Also, my spare aw4 has more miles on it than my current one...go figure

My previous '88 AW4 equipped XJ blew a trans cooler line. By the time I got home it was nearly dry. Filled it with fluid and drove it another 8 years without a hitch.
Contemplating swapping the AX-15 in my '90 for an AW4.

Guess I will quit worrying if DexVI is backward compatible to Dex II Hell, I might pour in some peanut oil from the last turkey fry.

That's actually the one area you need to be careful. They don't like synthetic.

Really ? I ran amzoil with no ill affects and planned on doing it again in my current XJ. If its true me and my wallet have no problem staying with whatever is on sale lol.

Search around. There have been a lot of people who have blown them up after running synthetic. Of course there are a lot who say they run it with no issues.

It's not worth it to me and that's coming from a guy who is a major believer in synthetic oil.

I thought all ATF was mostly synthetic anyways... I may be wrong.

There is a lot of disagreement about atf+4 in them, dexron/mercon is definitely fine, read up and run atf+4 if you want, I don't really have an opinion on it.

Valvoline MaxLife is 100% synthetic. I've been using it for 7 years with nothing but silky smooth shifts. Maybe my AW4 will blow up later today but I thought that the silliness about synthetics was long gone.

D.I.T.A said:

Really ? I ran amzoil with no ill affects and planned on doing it again in my current XJ. If its true me and my wallet have no problem staying with whatever is on sale lol.

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Pelican said:

Valvoline MaxLife is 100% synthetic. I've been using it for 7 years with nothing but silky smooth shifts. Maybe my AW4 will blow up later today but I thought that the silliness about synthetics was long gone.

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I would agree with the others that the AW4 is a very robust and reliable transmission. Shortly after I bought my XJ at 125,000 miles I had a problem with it. It turned out that two of the three shift solenoids in the transmission were bad. At that time I was driving mostly around town I shifted the gears manually until I was able to replace the solenoids. It does get a bit on the hot side in rush hour stop and go traffic in South Florida summer.

Every oil in my XJ have been changed to Amsoil at 135,000 miles and I see no ill effects. It is now at 275,000 miles and counting. My opinion is,...if the transmission (AW4 or any other built) is not working properly, fix it. If you are afraid the synthetic ATF will mess it up then stick with the old Dexron 2 or the Mercon.

techno1154 said:

I would agree with the others that the AW4 is a very robust and reliable transmission. Shortly after I bought my XJ at 125,000 miles I had a problem with it. It turned out that two of the three shift solenoids in the transmission were bad. At that time I was driving mostly around town I shifted the gears manually until I was able to replace the solenoids. It does get a bit on the hot side in rush hour stop and go traffic in South Florida summer.

Every oil in my XJ have been changed to Amsoil at 135,000 miles and I see no ill effects. It is now at 275,000 miles and counting. My opinion is,...if the transmission (AW4 or any other built) is not working properly, fix it. If you are afraid the synthetic ATF will mess it up then stick with the old Dexron 2 or the Mercon.

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Overall, I tend to agree. I think the main killer of transmissions is heat, and the AW-4 tends to run hot. Hot is where synthetic fluids shine. I also use Valvoline MaxLife with no problems. I also use it in my my wife's 2004 Honda Odyssey, which is famous for trans failure. She has 160K on the Honda. Knock on wood.

Use whatever fluid you feel comfortable with, just keep it as clean and cool as possible.

I have a problem with mine right now - has had a whine (more of a whir) in gear since I got it four years and 200,000 ago. Six months ago the tc stopped locking up when warm. Then I had an Exhaust leak that blew on the tranny and cooked the fluid while I was towing. Now after about twenty minutes of driving it starts to slip to the point I have to stop and wait half an hour before it moves again. It also sounds like hell. Grindy bag of marbles while in park or neutral and worse in gear. Especially when engine speed and trans speed are different. Quiets down while cruising. I have a parts jeep that I was going to pull the trans from but it is still under four feet of snow.

What does this sound like? Is this a tc problem? Possibly something else? I am not that skilled in auto trans work or specifics of diagnosis. I can do gears, change heads, all kinds of things, but have never taken a slush box apart.

Sounds like a TC issue, but after driving on it any debris has circulated into the transmission and damaged it as well probably. I would swap both out of the parts jeep as a unit. Make sure you flush the cooler lines and rad cooler very thoroughly or debris remaining in the system will come back to haunt your new trans as well.

As for my abused AW4, it was slipping in gear under heavy throttle on the highway Saturday so I checked the fluid level. Stick was dry again, added 2.5 quarts of dex/merc and it shifts like a dream again! I can't kill this thing... only a few more parts to get before an ax15 (also made by aisin warner) goes in.

Thanks for the comment. I had the ax15 in both my mj and previous xj. I wish I still had one now. 750,000 in my xj with only 2 clutches needed.