A leaking valve cover gasket is one of the most common oil leaks on the 4.0L XJ — and one of the most approachable to fix yourself. This guide covers the full replacement on 1987–2001 Cherokees.
If your XJ smells like burning oil after a drive, or you find oil pooled in the spark plug wells, the valve cover gasket is the first suspect. The original cork gasket on RENIX and early HO engines hardens and shrinks over the years; the oil weeps out, runs down the side of the head onto the hot exhaust manifold, and burns off — that's the smell. Left alone it won't strand you, but oil sitting in the plug wells will eventually foul plugs and degrade the wire boots, and a soaked engine bay makes every other leak impossible to trace.
One thing worth knowing before you start: leaks at the **rear of the valve cover**, near the firewall, run down the back of the block and are straightforward to mistake for a rear main seal failure. Before you condemn the rear main, clean the area, replace the valve cover gasket, and drive it a few days. The cover gasket is the cheaper, more common culprit — rule it out first.
The good news is the valve cover sits right on top of the engine with almost nothing in the way. The whole job is removing what crosses the cover, lifting it off, cleaning the mating surfaces, and setting the new gasket. The single thing that ruins this repair is overtightening — so read the torque step before you reach for the wrench.
| Part | Vendor | Est. price |
|---|---|---|
| Valve cover gasket — Fel-Pro rubber-coated steel core | RockAuto / Summit Racing / O'Reilly | — |
| CCV (crankcase vent) grommet and PCV grommet | RockAuto / Mopar | — |
| Spark plug tube seals (later HO valve covers with integrated tubes) | RockAuto / Mopar | — |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.