Symptoms
Oil weeping from the joint between the engine and bellhousing, and an oily crossmember and transmission. Rule out the valve cover, oil-filter adapter and pan gasket first.
The fix, step by step
- The 4.0 uses a two-piece rear main seal that can be replaced without removing the transmission.
- On a TJ, drain the oil, remove the starter and drop the oil pan.
- Off Road Xtreme warns this may mean removing the front axle for clearance, and Jeepz.com owners loosened the exhaust for room.
- Mark the rear main cap, remove both seal halves, and install the new halves without nicking the lip (dish soap helps the upper half slide in).
- Use only a dab of RTV where the halves meet the cap.
- Make sure you have the right seal for your engine, because 1987–99 and 2000–06 engines take different kits.
- Check crank end play while you're in there.
Tools & part numbers
- Pick
- thin punch
- O2-sensor wrench
- torque wrench
- RTV
- jack and stands.
Where to buy the parts
Crankshaft rear main seal kit, 00–06 TJ 4.0LExtremeTerrain ↗Amazon ↗
Rear crankshaft seal, 87–99 4.0L YJ & TJExtremeTerrain ↗Amazon ↗
TJ rear main seals (all brands)Quadratec ↗Amazon ↗
Hunting a used or discontinued part? Search eBay Motors for Jeep Wrangler TJ parts →
Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.