The valve cover gasket seals the top of the cylinder head where the camshafts and valvetrain live. Over time, heat and oil exposure cause the rubber gasket to harden, shrink, and crack. The result is oil leaking from the top of the engine, dripping down the sides, contaminating spark plug wells, and causing burning smells from the exhaust manifold area. Replacement is one of the most common and accessible internal engine repairs.
Symptoms of a Leaking Valve Cover Gasket
Visible oil seeping from the seam between the valve cover and cylinder head, oil pooling in spark plug wells (which can cause misfires by drowning the spark plug or insulating the boot), a burning oil smell from the engine bay (oil dripping onto hot exhaust manifolds), oil drips on the ground or on the engine cover, and slightly low oil level over time. The leak rarely causes immediate problems but worsens over time and can lead to misfires, smoking exhaust, and contamination of belts and electrical components.
Tools and Parts
You need a new valve cover gasket (always replace, never reuse), new spark plug tube seals if applicable (the rubber rings that seal around each spark plug well – if oil is in the wells, these are leaking too), gasket sealer for the corners where the cam caps meet the head (a tiny dab of RTV is usually called for in the workshop manual), basic socket set, torque wrench (essential – valve cover bolts are easy to overtighten and warp the cover), and clean rags. Some valve covers are aluminium and can be reused; others are plastic and may also need replacement if cracked.
Replacement Procedure
Remove anything blocking access to the valve cover – intake plumbing, ignition coils, spark plug wires, brackets, breather hoses, and so on. Take photos as you go for reference during reassembly. Disconnect any electrical connectors and label them if you are not sure. Loosen the valve cover bolts in a star or criss-cross pattern (the workshop manual shows the sequence). Lift the cover off, taking care not to drop debris into the engine.
Clean the gasket mating surfaces on the valve cover and cylinder head thoroughly. Any old gasket residue or dirt prevents the new gasket from sealing. Fit the new gasket to the cover (most modern gaskets clip into a groove in the cover, making installation easy). Apply small dabs of RTV sealer at the front and rear corners where the timing cover or cam caps meet the head, if specified by the manual.
Carefully lower the valve cover onto the head and refit the bolts. Tighten them in the correct sequence (usually starting from the centre and working outwards) to the specified torque – typically only 8 to 12 Nm. Overtightening warps the cover and causes the gasket to leak immediately. Reassemble everything you removed. Run the engine and check for leaks.
Valve cover designs, torque specifications, and gasket part numbers are vehicle-specific. MechanicMate offers PDF workshop manuals for over 960 models at mechanicmate.net/shop.
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