If you own a 1999 Jeep Cherokee with the legendary 4.0L inline-six engine, you know it is a vehicle built to last. However, even the most durable drivetrains have their weak points, and the torque converter seal is one of the most common failure points on the AW4 automatic transmission. A leaking seal can lead to low transmission fluid, slipping gears, and eventually catastrophic transmission failure if left unaddressed. For the DIY mechanic, replacing this seal is a challenging but rewarding job that can save hundreds of dollars in labor costs.
This comprehensive guide will walk you through the entire process of installing a new torque converter seal on your 1999 Jeep Cherokee, complete with a detailed transmission install diagram. You will learn the exact tools required, the step-by-step removal and installation procedure, and the critical torque specifications that ensure a leak-free seal. Whether you are a seasoned home mechanic or a first-time Jeep owner looking to tackle this job, this article provides the authoritative, practical information you need to get the job done right the first time.
Understanding the AW4 Transmission and Torque Converter Seal Function
The 1999 Jeep Cherokee uses the Aisin-Warner AW4 four-speed automatic transmission, a robust unit known for its reliability when properly maintained. The torque converter is the hydraulic coupling that connects the engine to the transmission, and it contains a seal at the point where the converter hub enters the transmission pump. This seal prevents transmission fluid from leaking out of the pump housing and into the bellhousing area. When the seal fails, fluid drips from the inspection cover on the bottom of the bellhousing, often mistaken for a rear main seal leak.
The torque converter seal is a relatively inexpensive part, typically costing between $10 and $25 for an OEM-quality replacement. However, the labor involved in replacing it is significant because the transmission must be removed or at least separated from the engine. The seal itself is pressed into the transmission pump housing, and it must be installed perfectly straight to avoid premature failure. A common mistake is installing the seal too deep or at an angle, which will cause it to leak immediately upon startup.
For the 1999 model year, Jeep used a specific seal design that is compatible with the 23-spline input shaft and the torque converter hub diameter of approximately 1.75 inches. It is critical to purchase the correct seal for vehicle. Using a seal from a different year or model can result in improper fitment and leakage. Always verify the part number against your vehicle’s VIN or consult a trusted parts supplier. The factory seal is made of a nitrile rubber compound that resists heat and ATF degradation, but aftermarket seals made from Viton offer superior longevity.
Tools, Parts, and Safety Preparation for the Job
Replacing the torque converter seal on a 1999 Jeep Cherokee is a major job that requires a specific set of tools. You will need a floor jack with a transmission jack adapter or a sturdy transmission jack, jack stands, a socket set ranging from 10mm to 19mm, a torque wrench capable of reading in foot-pounds, a seal puller or a flathead screwdriver, and a seal driver kit or a large socket that matches the seal diameter. You will also need a drain pan for transmission fluid, a new transmission filter and gasket, and approximately 8 quarts of Dexron III or Mercon V automatic transmission fluid.
Safety is paramount. The transmission weighs approximately 120 pounds dry, and with fluid, it can exceed 150 pounds. Never work under a vehicle supported only by a floor jack. Always use jack stands rated for at least three tons. Additionally, the exhaust system runs directly under the transmission, and it will be hot if the vehicle has been running. Allow the engine and exhaust to cool completely before beginning work. Wear safety glasses to protect your eyes from falling debris and transmission fluid.
You will also need a helper for certain steps, particularly when lowering the transmission from the engine. The transmission is heavy and awkward to maneuver alone. A transmission jack is highly recommended because it allows you to precisely control the angle and height of the transmission during removal and installation. If you do not have access to a transmission jack, you can use a jack with a piece of plywood to distribute the weight, but this is less stable and more dangerous.
Step-by-Step Removal of the Transmission and Torque Converter
Begin by disconnecting the negative battery terminal. This is a critical safety step that prevents accidental starter engagement and electrical shorts. Next, raise the vehicle on jack stands, ensuring it is level and stable. Remove the transmission fluid pan by unbolting the 10mm bolts around the perimeter. Be prepared for fluid to drain from the pan. Once the pan is off, remove the filter by pulling it straight down from the pump. Allow the fluid to drain completely into the drain pan.
With the pan removed, you can access the valve body and the torque converter drain plug, if equipped. Not all 1999 Cherokees have a drain plug on the torque converter. If yours does, rotate the engine by hand using a socket on the crankshaft bolt to align the drain plug with the access hole in the bellhousing. Place a drain pan under the bellhousing and remove the plug to drain the converter. This step is optional but highly recommended to reduce weight and mess.
Now, disconnect the transmission cooler lines from the transmission. These are located on the driver’s side of the transmission case. Use a line wrench to avoid rounding the fittings. Have a rag ready to catch residual fluid. Next, disconnect the shift linkage, the throttle valve cable (if equipped), and all electrical connectors. Remove the starter motor, as it is bolted to the bellhousing and will interfere with transmission removal.
Removing the Old Seal and Installing the New Torque Converter Seal
With the torque converter removed, you can see the old seal pressed into the front pump housing. The seal is located at the center of the pump, surrounding the input shaft. Use a seal puller to carefully pry the old seal out. If you do not have a seal puller, you can use a flathead screwdriver, but be extremely careful not to scratch or gouge the pump housing bore. A damaged bore will cause the new seal to leak. Work your way around the seal, prying gently from multiple angles until it pops out.
Clean the seal bore thoroughly with a lint-free rag and brake cleaner. Remove any old sealant, dirt, or debris. Inspect the bore for any burrs or damage. If you find any, use a fine file or sandpaper to smooth them out. The bore must be perfectly clean and smooth for the new seal to seat properly. Also, inspect the pump housing for cracks or damage. If the pump housing is damaged, the entire transmission must be rebuilt, which is beyond the scope of this guide.
Reinstalling the Torque Converter and Transmission
Before reinstalling the torque converter, lubricate the converter hub with a thin layer of ATF. Slide the torque converter into the pump, rotating it gently as you push. You will feel the converter engage the pump gears. Continue pushing and rotating until the converter is fully seated. You should hear and feel three distinct clicks as the converter engages the pump. The converter should sit approximately 1/2 inch to 3/4 inch recessed into the bellhousing. If it is flush with the bellhousing face, it is not fully seated.
Measure the distance from the converter mounting pads to the bellhousing face. This distance should be consistent for all four pads. If one pad is closer or farther than the others, the converter is not seated correctly. Remove it and try again. This step is critical. Installing the transmission with an unseated converter will destroy the pump within seconds of starting the engine.
Key Takeaways
- ✓ The torque converter seal is a common failure point on the 1999 Jeep Cherokee AW4 transmission, and replacing it requires transmission removal.
- ✓ Always replace the transmission filter, gasket, and fluid when performing this job to ensure long-term reliability.
- ✓ The torque converter must be fully seated into the pump with three distinct clicks before reinstalling the transmission to avoid pump damage.
- ✓ Use a seal driver tool or a properly sized socket to install the new seal flush with the pump housing face, and always lubricate the seal lip with ATF.
- ✓ Torque specifications are critical: bellhousing bolts at 35 ft-lbs, torque converter bolts at 40 ft-lbs with Loctite, and pan bolts at 10 ft-lbs.
Frequently Asked Questions
How do I know if my torque converter seal is versus a rear main seal leak?
A torque converter seal leak typically presents as fluid dripping from the bellhousing inspection cover, while a rear main seal leak drips from the back of the engine oil pan. The fluid from a torque converter seal is red (ATF), while engine oil is amber or dark. You can also use a UV dye additive to trace the leak source.
Can I replace the torque converter seal without removing the transmission?
No, the torque converter seal is located inside the front pump housing, which is only accessible when the transmission is separated from the engine. There is no access panel or shortcut for this repair. The transmission must be removed.
What type of transmission fluid should I use in my 1999 Jeep Cherokee AW4?
The AW4 transmission is designed to use Dexron III or Mercon V automatic transmission fluid. Do not use Dexron VI or any synthetic fluid that is not specifically labeled as compatible with Dexron III. Using the wrong fluid can cause harsh shifting and premature seal failure.
How long does it take to replace the torque converter seal on a 1999 Jeep Cherokee?
For an experienced DIY mechanic with proper tools, the job takes approximately 6 to hours. For a first-timer, plan for a full weekend. The most time-consuming parts are removing and reinstalling the transmission and ensuring the torque converter is properly seated.
What are the symptoms of a failing torque converter seal?
The primary symptom is a visible transmission fluid leak from the bellhousing area. You may also notice a burning smell from fluid dripping onto the exhaust, low transmission fluid levels, and eventually slipping or delayed engagement when shifting into drive or reverse.
Conclusion
Replacing the torque converter seal on your 1999 Jeep Cherokee is a challenging but entirely achievable DIY project that can save you significant money and extend the life of your vehicle. By following the detailed steps outlined in this guide, the critical torque specifications and the proper technique for seating the torque converter, you can ensure a leak-free repair that will last for many miles. Remember that patience and attention to detail are your greatest assets in this job.
Now that you have the knowledge and the step-by-step diagram, it is time to gather your tools and get to work. by inspecting your Cherokee for signs of a transmission leak, and if you confirm it is the torque converter seal, do not delay the repair. A small leak today can become a major transmission failure tomorrow. With the right preparation and this guide by your side, you can restore your Jeep’s drivetrain to perfect working order and enjoy many more years of reliable off-road and daily driving performance.
