Symptoms
Oil dripping from where the engine meets the bellhousing, and an oily transmission and crossmember. Rule out the valve cover and oil pan gaskets first, because oil runs downhill.
The fix, step by step
- The AMC six uses a two-piece rear main seal that is replaced from underneath without removing the transmission.
- Drain the oil, remove the starter and the oil pan, and mark the rear main bearing cap so it goes back the same way.
- Remove both seal halves, using a pick and a thin punch to work the upper half around the crank.
- Install the new halves with only a dab of RTV where they meet the cap, being careful not to nick the lip (one owner had to buy a second set).
- Torque the cap bolts to 80 ft-lb, the rear main bearing cap figure for the 4.0 and 4.2 in ExtremeTerrain's YJ engine torque table, refit the pan with a new gasket and refill.
- While the pan is off, check crank end play.
Tools & part numbers
- Pick
- thin punch
- torque wrench
- RTV
- oil pan gasket
- new oil and filter.
Where to buy the parts
OMIX 17458.03 rear main seal kit, 87–99 4.0L and 72–90 4.2LQuadratec ↗Amazon ↗
Rear crankshaft seal, 87–99 4.0L YJ & TJExtremeTerrain ↗Amazon ↗
YJ engine gaskets and hardware (oil pan gasket)Quadratec ↗Amazon ↗
Hunting a used or discontinued part? Search eBay Motors for Jeep Wrangler YJ 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.