View Full Version : AW-4 Toasted???

November 19th, 2017, 03:37
1997 XJ, 4.0, AW-4, NP231, 3" lift, 440K miles.

For the past few days when I start driving in the AM I heard a whining sound that I thought could possibly be the torque converter. I checked fluid, it was full, red and maybe a touch of burnt smell. (It's been 12K miles since last fluid change.)
At that time the shop put in 5 qts of ATF+4, and 2 qts of Dex/Merc. He didn't have all 7 qts of Dex/Merc and he said that this would be OK.

Yesterday I went trail riding and on way home on the Interstate the transmission apparently died. My engine RPM's went over 3000 and there was no power to the wheels. It was like the Tranny was in Neutral. Had to be towed home.
This tranny was bought brand new and has 153,000 miles on it.

Anyway, is the Tranny toasted, or could it be a "minor" problem that can be fixed?

Appreciate any help-

November 19th, 2017, 08:26
First of all ATF+4 is a no no for the AW4, second, the AW4 takes 8 qts.


If the transfer case was in Neutral, even if the transmission was in gear, you would get no power to the wheels. Your t-case linkage could have come loose in your trail riding.

...and then find a new mechanic.

November 19th, 2017, 15:53
Test the shift solenoids. Unplug the TCM and see if it shifts manually. Then, find a new mechanic.

November 19th, 2017, 16:14
did the wining sound change with vehicle speed or engine speed?

November 20th, 2017, 05:19
could be linkage broke, could be out of fluid, lot of guessing really

November 21st, 2017, 13:38
At the time of the failure did you check the fluid again? Did you lose power all at once or did the trans start to slip and then completely lost forward gear? Need more info to help specifically.

I'm not AW4 expert, but do know they are pretty tough. Can't comment on the atf+4 mentioned above, but have heard that its not good to mix them, not sure why though.

I would not expect catastrophic trans failure to manifest without some sort of bang, or obvious problem. Try and describe the failure incident in detail and what you checked after you got stopped on the highway? Trans fluid? smells? reverse? shift t-case back and forth?

Let us know

February 4th, 2018, 14:13
I lost power all at once. The tranny went from full power to being like it was like in Neutral.
(For a few days before the trail ride, I heard a slight wining sound that to me reminded me of a torque converter about to fail).

Since my last tranny service, where the shop used 2 qts. Dex/Merc and 5 qts of ATF+4, this was my first time on the trail ride. (They only had 2 qts of Dex/Merc)

I always have my tranny served regularly and used Dextron/Merc as the only fluid. That is why I had them document what they put in it.

I was on a trail ride the day the tranny died, On the ride, we were on forest service roads, going slow all day. No-one needed winch, and road was slow but any SUV with ground clearance could have handled these trails easily.

I was told by the tranny shop that driving like this causes more heat on tranny than usual.

My tranny died due to Torque converter failure. The tranny shop was sure of this as the TC was a bluish color. This AW-4 had only around 150K miles on it. This was a factory new tranny, as my original tranny went 275K miles before failing. I bought a brand-new tranny to replace it. I believe that the fluid was the culprit for this failure.

Was the fact that it had the wrong fluid in it the cause for this?
I appreciate any thoughts on this.
If the fluid was the cause I will be suing the tranny shop for putting in the wrong fluid.


jeep ride
February 4th, 2018, 16:44
Atf 4 is a no no for sure

jeep ride
February 4th, 2018, 16:45
Dont know how long it would take to damage your tranny though

February 8th, 2018, 18:00
Some words about my experience with AW-4 transmissions. I had a broken piston ring in my 88XJ for awhile and at 385,000 miles I decided to rebuild/modify my 4.0L. So while I had the engine and trans out, I decided to rebuilt the AW-4 as well. During tear-down, I miked every part in that trans and recorded it. Guess what? That AW-4 didn't need to be rebuilt! To say I was impressed with my AW-4 would be an understatement! Well since I had the trans rebuild kit I rebuilt it anyway. Those rebuilds were about 200,000 miles ago. My 88XJ runs very well, is my DD, and never ceases to amaze me. One thing that can cause engine or trans failures is oil foaming caused by either poor oils or mixtures of incompatible oils. Likewise, installing a larger trans cooler is always a good idea; i.e. the cooler the oil, the longer the trans life.

Best regards,


February 8th, 2018, 20:08
If the TC failed I find it hard to believe the fluid was the reason. I ran plus type for years, my trans had almost 290k before it died. And judging by the noise it made I suspect a bearing grenaded. It had amsoil universal at the time. There's a lot of fluid debate running around here. Im not convinced plus type will ruin your trans but that's my opinion. Even my dipstick says "Mopar plus type 7176 or dexron". 7176 was superceded by +4.

February 9th, 2018, 04:40
Wrong fluid wouldn't cause sudden failure but I could see it causing a slow but steady failure. I've actually had a torque converter fail on me. Just driving along, reached the top of a bridge and pop, 6 neutrals and a park. Broke the center of the converter off. Pull a line and put a pressure gauge on it. See if you have line pressure.
This did fail in a dodge 1500. 05.

February 9th, 2018, 07:58
Rolling or sliding(bushing) type bearings, immersed in oil, require oil boundary layers between the rolling/sliding surfaces to function properly. Oil foaming removes the oil boundary layers and allows metal-to-metal galling contact which cause early/rapid bearing failures. Likewise, if certain temperatures/pressures are present in the oil; cavitation can occur and destroy/disintegrate the bearings even faster. Initial cavitation failures typically show a sand-blasted texture to the metal surfaces which gets worst very quickly.

Best regards,