Valve Cover Gasket Leak Symptoms and How to Fix It

Common valve cover gasket leak symptoms are oil seeping around the edges of the valve cover, a burning oil smell or light smoke from the engine bay as oil drips onto the hot exhaust, oil in the spark plug wells that can cause misfires, and slowly dropping oil level. A valve cover gasket is usually one of the easier and less expensive oil leaks to fix.

Valve cover gasket leak symptoms

• Oily, dusty buildup along the valve cover edge
• Burning oil smell, especially after a drive; see burning smell from car
• Wisps of smoke from the engine bay when stopped
• Oil in spark plug wells, sometimes with misfires; see engine misfire
• Oil level dropping between changes

Why valve cover gaskets leak

Rubber and cork gaskets harden and shrink with years of heat cycles. Over-tightened bolts can crush the gasket, and a clogged PCV valve raises crankcase pressure and pushes oil past seals; see PCV valve.

Is it the valve cover or something else?

Oil runs downhill, so a valve cover leak can coat the side of the engine and look like a lower leak. Clean the area, drive briefly and look for where fresh oil first appears. A UV dye kit makes the source obvious; see oil leak, rear main seal leak and oil pan gasket leak.

Fixing it

1. Remove the coils or plug wires and any covers in the way.
2. Remove the valve cover and clean both sealing surfaces carefully.
3. Fit a new gasket, plus spark plug tube seals and grommets where the design uses them.
4. Tighten the bolts in the specified sequence to the specified torque; over-tightening causes new leaks.

Signs it is time to replace the gasket

A gasket that has started to seep usually keeps getting worse. If the leak has reached the exhaust manifold, the spark plug wells or the alternator below, or if you are already removing the valve cover for spark plugs or other work, replace the gasket then. On many engines the job takes an hour or two with basic tools.

Is it safe to drive?

A small seep is not urgent, but oil dripping onto the exhaust can smoke and, in rare cases, catch fire, and oil in the plug wells damages coils and plugs. Keep the oil level topped up and fix it soon.

Related

If oil is being burned inside the engine rather than leaking outside, see engine burning oil. Choosing oil after the repair? See synthetic vs conventional oil.

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