AW4 Overhaul Kit 2000

A 2000 or 2001 Jeep Cherokee XJ with the AW4 that leaves drips under the bellhousing and tail housing, takes a moment to engage Drive on a cold start, or is coming apart for a rebuild anyway needs a fresh set of soft parts before it goes back together. This is the Transtec overhaul kit by Freudenberg-NOK for the 2000-and-later version of the Aisin A340 family, which includes the AW4 (Aisin's AW30-40LE). It is the gasket and seal set only: pan gasket, valve body and case gaskets, lip seals, O-rings and the sealing rings that hold pressure in each clutch circuit. It does not include friction discs, steel plates, a band or a filter.

What the overhaul kit does in an AW4

The AW4 applies its clutches and brakes with oil pressure. The valve body sends that pressure through the case and into rotating shafts and drums, and the oil only gets where it is supposed to go because of rubber O-rings, sealing rings on the shafts and lip seals on the pistons. Paper gaskets between the valve body, separator plate and case keep one circuit from bleeding into the next, and lip seals at the front pump and the rear housing keep the fluid inside the case. After twenty-plus years of heat cycles those parts harden and shrink. Pressure drops a little in every circuit, the clutches apply softer and slip a little longer, and the fluid finds its way out. Replacing the whole set at once is the foundation of any AW4 rebuild, even when the hard parts are reusable.

Symptoms that call for new seals and gaskets

• Fluid leaking at the front pump seal, the pan, the extension or rear housing, or the shift shaft
• Slow engagement into Drive or Reverse when cold that improves as the fluid warms
• Shifts that grow soft or flare slightly once the transmission is hot
• Low fluid level with no single obvious leak point
• A rebuild in progress where every seal and gasket has to be replaced anyway

How to confirm what your AW4 needs

A leak alone does not always mean a teardown. Clean the case, then trace the wet spot to its highest point; a pan gasket or rear seal can be done in the truck. If you have slipping, flare or a missing gear, check the electrical side next, because shift solenoid and sensor faults are common on the AW4 and can feel like mechanical failure. The 1997 Cherokee service manual tests each shift solenoid at 11 to 15 ohms. A failed lockup circuit is a cheaper fix with an AW4 TCC solenoid. If the fluid is burnt and the pan holds friction material, the clutch packs are worn and you need frictions as well; in that case the AW4 master rebuild kit covers soft parts and clutches together.

Fitment

This kit is cataloged for 2000-and-up units in the A340 family: the AW4 / AW30-40LE, A340E, A340F, A340H (AW30-80LE), A343E and A343F. For Jeep owners that makes it the match for the 2000 and 2001 Cherokee XJ 4.0L, the last two years of the AW4. Toyota and Lexus applications such as the Tacoma, 4Runner, Tundra, Sequoia and Land Cruiser with these transmissions are also in the catalog listing. Aisin changed valve body and case details within this family over the years, so the kit carries more than one valve body gasket pattern; match each gasket to your separator plate before installing and set the extras aside. For a 1987-1999 Jeep, see the AW4 overhaul kit for earlier years. Not sure? Send us your year and VIN. All of our AW4 parts are on the Aisin transmission page.

Install notes

• Soak new rubber seals in clean ATF and coat the sealing rings with assembly lube so they stay centered while you slide the drums on.
• Install the front pump seal and rear housing seal with a driver that pushes on the outer case of the seal, never the lip.
• The AW4 overhaul manual lists a 38.19 mm maximum bore for the front pump bushing. If yours is past that, the new pump seal will leak again quickly.
• Air-check each clutch and brake circuit through its case passage before the valve body goes on; a sealed circuit makes a clean thump when it applies.
• The overhaul manual calls for Mercon ATF with Dexron II as the alternate. Refill, start the engine, cycle the selector, and check the level hot.
• Flush the cooler lines or add a new AW4 transmission cooler, and replace a worn AW4 valve body while the pan is off.

Does this kit include clutches or steels?

No. It is a gasket and seal kit: pan gasket, valve body and case gaskets, lip seals, O-rings and sealing rings. If your clutch packs are worn, choose the AW4 master rebuild kit or buy frictions and steels separately.

Will it fit my 1997 Jeep Cherokee?

This kit is cataloged for 2000-and-up units, which on the Jeep side means the 2000 and 2001 Cherokee XJ. For 1987-1999 Jeeps use the earlier-year AW4 overhaul kit, or send us your year and VIN and we will match it.

Why are there extra gaskets in the box?

One kit covers several transmissions in the A340 family, so it includes more than one valve body and separator plate gasket pattern. Lay each one over your plate and use the one whose holes line up exactly.

What fluid should I use?

The AW4 overhaul manual specifies Mercon ATF, with Dexron II as the listed alternate. Use a quality Mercon-rated fluid and check the level with the transmission at operating temperature.

Can I fix a front pump leak with this kit without a full rebuild?

The kit includes the front pump seal, but the transmission has to come out to reach it. While it is out, check the pump bushing, because a worn bushing is a common reason the old seal failed.