AW4 transmission that overflows

[Phil.R]

I'm looking to buy a stock '97 XJ Sport with 122k and 4l/AW4/NP242 that has some issues (for cheap). I think it won't be a problem to solve most of them but the AW4 transmission sometimes overflows when hot. I don't know exactly when it does it as I didn't talk to it's current owner. I know that the radiator was replaced earlier this year and there's no added external trans cooler. I have driven it on a short distance and I didn't notice anything wrong with the transmission.
I currently have a 1988 with the same transmission and I used to have a 1989 and never had such problems with these (and they both had bad radiators and engine overheating issues at some point!).

I assume that it will need to have it's transmission flushed soon but I'd like to know what could cause this overheating condition and have that fixed before.

Also, can somebody tell me if the transmission (or transmission/transfer case) from my 1988 could be swapped in a '97? (both have a NP 242). I think that the number of splines on the output shaft have changed in the early nineties and probably other things (like there's no "performance" switch in the newer ones and the older one uses a speedo cable).

 

[kastein]

You are correct.

You would have to swap some parts within the transfer case or swap the transfer case and rear driveshaft as well, then put your VSS in instead of the speedo cable.

You may also have to swap the TV cable, I'm not sure. Some wire splicing may be required but nothing extraordinary. The comfort switch only affects the TCU, the transmission hardware is the same, so you're fine there. Double check that the 97 wasn't a 98 model built very late in 97 and sold as a 97, if it was, it could have an input speed sensor and the 89 tranny will NOT work. All you have to do to verify this is look for the input speed sensor, it's mounted up near the shift linkage on the driver side of the tranny housing right by the bellhousing. If there is no such sensor on the 97 (it has two pins in the plug) you are good to go.

I think there was also a minor overdrive ratio change from .75 to .70 or so or vice versa, but that's no big deal.

Most likely though the transmission just needs to be flushed or there is too much fluid in it. Check the level, if it's too high or too burnt/gross try draining some out till it's at the right level or try flushing it.

 

[Phil.R]

Thanks for the quick reply! I'll verify these things!

I'd rather not swap the transmission with the higher mileage transmission from my 1988 but I asked just in case there would be a major problem with it!

Another thing I noticed on the '97 is the part time light that stays on on 2wd mode but it goes off when the tc is in full time mode.

My 1988 also has an issue with that but it's the full time light that sometimes goes on in all modes (2wd, part time, low...), in low vacuum conditions like when accelerating.

 

[Tim_MN]

Used low mileage Aw-4's are cheap as dirt, there is no reason to modify one when you can get exactly what you need for $100-250.

 

[Phil.R]

That's true!

 

[joe_peters]

As said, flush the transmission--old tired fluid = slippage = heat = fluid puking.

Consider adding a trans cooler.