Cork gasket on Renix and early HO; rubber on later HO. Leaks drip down the manifold and burn off, often producing the 'XJ oil smell' from the engine bay.
Valve cover gasket leaks are nearly universal on XJ over 150k miles. Symptoms include oil pooling around spark plug tubes, oil running down the exhaust manifold and burning off (faint blue smoke at idle, oil smell on shutdown), and oil in the spark plug wells. Replacement is straightforward: remove the air intake tube, throttle linkage, electrical connectors crossing the valve cover, and the 7 valve cover bolts (or 13 studs/nuts on later years). The Fel-Pro VS50425R is a rubber-coated steel-core gasket that lasts far longer than the original cork. Clean both surfaces thoroughly. Torque the valve cover bolts to ONLY 85-90 in-lb (about 7 ft-lb) - the head and cover are straightforward to crack from overtorque. Do not overtighten in attempt to stop a future leak; this warps the cover. The cork gasket is sometimes glued to the cover with Permatex 80697 The Right Stuff, but a clean reusable gasket is better.
| Part | Vendor | Est. price |
|---|---|---|
| Valve cover gasket Fel-Pro | RockAuto | ~$25 |
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.