The Jeep service manual recommends changing the fluid every 25,000 miles. I rarely see XJs get serviced that often.

Changing the fluid and filter requires removing the transmission pan. A handy drain plug on the AW4 allows for fluid draining. Odly for the XJ, it uses a 14 mm wrench to remove it. But, I recommend changing the filter as well.

But before you start, I recommend removing the bolt that holds the filler tube to the engine block. it has a 13mm head and is hard to get to. I used a long extension and a swivel joint.

Now raise the Jeep and support the transfer case. Remove the cross member by removing the four transmission mount nuts (13mm) hidden inside the cross member. Then remove the four bolts (15mm) holding the cross-member to the body.

Remove the plug and drain as much fluid as possible. It will be about a gallon to five quarts so make sure you have a large enough pan.

Next, remove the perimeter bolts (10mm). level a couple in the front partially threaded in to allow the pan to tip back and fully drain.

Now, you need to try to separate the two parts of the filler tube. If these have been together a long time like most XJ that do not get serviced every 25000 miles, this joint will not come apart. To remove the pan with the filler tube still attached, and remove all the pan bolts. Then, working from the engine bay, work the hold-down tab over the bell housing. Now, lower the transmission slightly to make some space between the body and the transmission. You should be able to work the pan out now with the filler tube attached.

It is not necessary to separate the filler tube, but it will be easier to reinstall if you do.

Now remove the for bolts (10mm) holding the filter to the valve body, Remove the filter making sure both gaskets come off with the filter.

Inspect the solenoid wiring and make sure the mating surface is clean. Install the new filter and tighten up the four bolts,

Now, clean the inside of the pan and inspect the magnets for debris. The more fuzzy metal there is the more wear the clutches have. Install the gasket by pressing a few mounting bolts through the gasket to get it lined up.

Note the pan is glued on at the factory. If the pan did not have a gasket, take time to carefully clean both mating surfaces. You can use a sealant instead of a gasket but I like the one that comes in the WIX kit.

Carefully line up the bolts and start them by hand once you get some close to the corners the gasket and pan should line up. If you still have the full filler tube attached to the pan, make sure the mounting tab is in the proper place in the front of the bell housing before starting any bolts.

I don’t think I have ever serviced an AW4 transmission pan that did not have at least one stripped bolt. So have a Helicoil kit ready. (6mm x 1.0) You can do a tread repair with the pan in place so go ahead and put in all the good ones and do the thread repair on the bad ones.

Once the on is in place, install the top part of the filler tube. I find it easiest to drop the tube from the top and then align it from underneath. Then I use a rubber hammer to tap in down into place. Reinstall the mounting bolt on the bell housing.

Now, raise the transmission back up into position and reinstall the cross member. Usually, the transmission will shift a little to one side as it is raised and lowered so be prepared to pry a bit to realign the cross-member bolts. I find it easiest to mount the cross member to the transmission mount while it is slightly lowered and then jack up the cross member to the body.

Refill the transmission with fresh fluid. It will take about 5 quarts. I like to put in four and then run the engine, cycle through the gears, and check for leaks. Then, check to see how much more fluid to add.

Fresh fluid and filter should help keep your AWW4 happy for a long time. These are very durable transmissions as lo gas they are not severely over heated or run low on fluid.

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Last week my 1988 XJ off road Jeep played a trick on me. I needed to move it out of the way so I could get my tractor out. It started with an extended crank. This Jeep normally stars quickly so this was odd.

It was stumbling and running rough so I decided to take the long way around to it s parking spot. About half way round the driveway, the Jeep almost died but out of the corner of my eye I saw the REM indicate crazy numbers for the engine RPM. Like 9000 or so. The factory tach was showing 500 to 600 at the time.

I finally got it around to its parking place and shut it off. After grading the driveway, I decided to take a look at the Jeep. Now it refused to start. The REM was showing zero RPM and would put an asterisk beside the number if I continued cranking.

So I hooked up a tow rope and drug it into the shop.

I noticed the wires to the Crank Shaft Position sensor were melted form being too close to the exhaust so I decided to check the sensor output. My scope showed a trace that matched the one int he RENIX manual exactly.

I then suspected the J10 connector so I pulled the seat, laid in the floor and pulled the ECU out where I could get to the wires. I hooked up the the Crank Sensor pins and got the same proper trace.

I figured I must have a bad ECU at this point. I have been wanting to swap to a 1990 ECU for a while so I jumped on EBAY and Got one on order. I also ordered a new CPS just in case.

Once the replacement ECU arrived, I plugged in with it laying in the floor board and gave the starter a spin. I got the exact same symptoms. No start and zero RPMs on the REM display.

The new CPS arrived the next day so I set myself to the task of changing it. This is not easy on the particular Cherokee as I have modified the cross member for extra clearance that makes it impossible to get a tool on the upper CPS bolt.

I lowered the trans enough for access and swapped out the sensor. I plugged it in and expected the engine to start. But no go. Still the same zero RPMs on the REM.

Next I decided to go back to basic and check spark and fuel. I put an inline spark checker on the coil wire and saw flashes as I spun the starter. That meant the CPS was actually working.

Next I connected the fuel pressure gauge. Zero PSI! I had found the problem. I squired a blast of starter fluid in the intake pipe and spun the starter. I got a quick fire and then stall as the vapor quickly burned off.

I could hear the fuel pump run so I then set out to find what the trouble was. Before going much further, I decided to drop in an extra gallon of gas that is normally set aside for the mini bike. The fuel pump made a different sound and this time the engine fired right up.

It was out of gas the whole time. I guess now I need to work on the gas gauge.

My 1999 Rock Crawler XJ has been retrofitted with disk brakes. I think they are from a ZJ. However, whoever made the swap did not replace the wheel studs. The studs intended for drum brakes are way too short when used with disk brake rotors.

The right time to swap the studs would have been while the axles were out making the brake swap. But since that did not happen and I really did not want to pull the axles shafts out of the locker just to change wheel studs, I looked for another method.

With the rotor removed, I could just fish out the short stud past the parking brake shoe. However, there was no hope of installing a longer one.

So, I removed the hold down clip and the lower spring and adjuster so I could swing the parking brake shoe out of the way. I used studs from a 2000 XJ front hub for the replacements. This seemed to be the longest stud I could fit without removing the axle.

I used a big hammer to tap out the old studs. I do not intend on reusing them so I just pounded on the end of the stud until it popped out of the splines. I then used a magnet to fish it out past the brake shoe.

I harvested studs from on old hub I had in the scrap pile. I threaded on an old trailer lug nut until it was even with the end of the stud and hammered it out. A little heat on the hub made them much easier to remove.

After harvesting five, I decided to just buy five more at the parts store. I used Dorman part number 610-449.1.

To install the new studs I used a wheel stud install tool. https://amzn.to/3WJPzBA I lubed up the splines, and the tool and use my impact gun pull the stud into place. The first lug nut pulled in about 8 of the studs before it started to be hard to thread on. So I swapped to a different lug nut for the last couple. I would not recommend using one of the lug nuts you plan to use on the Jeep for pulling the studs into place. I let them cool a bit and then torqued them to 75 foot lbs before installing the wheels. I slipped the rotor on temporarily to make sure the heel of the stud did not interfere with pulling it down fully.

I then put the spring, adjuster and clip back on the rear shoe and reinstalled the rotor. I then put on the wheel spacers and noted the thread depth. I had about one thread through the lug nut so the length turned out perfect for my application. I torqued everything down and then mounted my wheels. I will recheck the torque again after I drive a few miles as I am sure the studs will settle in more as they heat cycle.